UNITED STATES DEPARTMENT OF THE INTERIOR 

THE MOLLUSCAN FAUNA OF THE 

ALUM BLUFF GROUP OF FLORIDA 

PART I. PRIONODESMACEA AND 

ANOMALODESMACEA 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 142-A 

DEPARTMENT OF THE INTERIOR 

Hubert Work, Secretary 

U. S. GEOLOGICAL SURVEY 

George Otis Smith, Director 

Professional Paper 142-A 

THE MOLLUSCAN FAUNA OF THE ALUM BLUFF 

GROUP OF FLORIDA 

BY 

JULIA GARDNER 

PART I. PRIONODESMACEA AND ANOMALODESMACEA 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1926 

For sale hy thP SupPrintt•nrlent of l>ocum(•nts, F. S. OowrnmPnt Printing OfficP, ·washington 21i, D. C. 

Introduction ___ -----_------- _____________________ _ 

Distribution of the fauna __________________________ _ 

Systematic descriptions ____________________________ _ 

Order Prionodesmacea _________________________ _ 

Superfamily N uculacea ____________________ _ 

Family N uculidae _____________________ _ 

Family Ledidae _______________________ _ 

Superfamily Arcacea ______________________ _ 

Family Limopsidae ____________________ _ 

Family Arcidae _______________________ _ 

Superfamily Pteriacea _____________________ _ 

Family Pinnidae ______________________ _ 

Family Pedalionidae __________________ _ 

Family Pteriidae ______________________ _ 

Superfamily Ostracea ______________________ _ 

Family Ostreidae _____________________ _ 

Superfamily Pectinacea ____________________ _ 

Family Pectinidae ____________________ _ 

Family Spondy lidae ___________________ _ 

Family Limidae _______________________ _ 

CONTENTS 

Page 

1 

3 

8 

8 

8 

8 

10 

21 

21 

22 

39 

39 

39 

39 

40 

40 

43 

43 

50 

52 

Systematic descriptions-Continued. 

Order Prionodesmacea-Continued. 

Superfamily Anomiacea ____________________ _ 

Family Anomiidae _____________________ _ 

Superfamily Mytilacea ____________________ _ 

Family Mytilidae _____________________ _ 

Family Juliidae _______________________ _ 

Order Anomalodesmacea _______________________ _ 

Superfamily Anatinacea ___________________ _ 

Family Periplomatidae ________________ _ 

Family Thraciidae ____________________ _ 

Family Pandoridae ____________________ _ 

Superfamily Poromyacea ___________________ _ 

Family Verticordiidae _________________ _ 

Family Cuspidariidae ___________ ----- __ _ 

ILLUSTRATIONS 

Page 

53 

53 

57 

57 

60 

61 

61 

61 

62 

62 

63 

63 

64 

Page 

PLATE I. Map of northern and western Florida showing principal fossiliferous localities of the Alum Bluff group__________ 2 

11-XV. Prionodesmacea and Anomalodesmacea of the Alum Bluff grouP------------------------------------------ 65-79 

III 
ACKNOWLEDGMENTS 

I have the honor and the pleasure to offer my sincere thanks to 

those who have aided me by general advice and by knowledge of 

detail through the long period of preparation demanded by this 

work: 

To Dr. William H. Dall, the wise counselor and a perennial leader 

among American conchologists. Daily access to his large personal 

library and daily contact with his long familiarity with nomenclatorial mazes have rendered inexcusable any inaccurate or perfunctory treatment of the bibliographic phase of this paper. 

To Dr. Paul Bartsch for the courtesies and cooperation tendered by 

the Division of Mollusks of the United States National Museum. 

To Dr. Henry A. Pilsbry, of the Academy of Natural Sciences, 

Philadelphia, for the generous loan of material and frequent access 

to the collections of the academy. 

To Prof. E. W. Berry, of Johns Hopkins University, for counsel 

and the freedom of the paleontologic laboratory of the university. 

To Dr. E. H. Sellards, former State geologist, and to Mr. Herman 

Gunter, present State geologist of Florida, and to other officials of 

the State Geological Survey for their friendly cooperation in the field. 

To Mr. Truman H. Aldrich for the inspiration of his long-continued, 

patient, and intelligent interest and the benefits of his many years of 

discerning study of the Gulf Tertiary deposits. 

To Dr. T. Wayland Vaughan, under whose direction this work was 

initiated. 

To my associates upon the United States Geological SuiTey, 

Messrs. L. W. Stephenson, T. W. Stanton, and C. Wythe Cooke, and 

especially to Messrs. W. P. Woodring and W. C. Mansfield, who 

through many years have been susceptible to importunate requests for 

information and assistance. 

JuLIA GARDNER. 

IV 
THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

By JuLIA GARDNER 

PART I. PRIONODESMACEA AND ANOMALODESMACEA 

INTRODUCTION 

The Alum Bluff deposits consist of a series of sands 

and clay~, for the most part unconsolidated, in many 

places highly calcareous, and carryinO' a varied and 

prolific fauna. Three distinct faunas o are recoO'nized 

in the deposits, and largely on the basis of o these 

faunas the Alum Bluff is here elevated to the rank of 

a group and divided into three formations, each characterized by a distinctive fauna. These formations 

are here named, in descending order, Shoal River formation, Oak Grove sand, and Chipola formation. 

The Mollusca of the Alum Bluff group include between 800 and 900 species. The detailed discussion 

of the stratigraphy will follow the systBmatic treatment of the fauna, for the stratigraphy is in large 

measure deduced from the fauna. 

The section at Alum Bluff on Apalachicola River 

F:a., was first. ~ited by Langdon 1 in 1889. He recog~ mzed two fossiliferous horizons and referred them both 

to the Miocene, apparently without any appreciation of 

the time interval between them. The basal fossiliferous bed at Alum Bluff is now correlated with the 

"Chipola marl member" of Matson and others, and 

the upper beds are correlated with the Choctawhatchee 

Inarl. Johnson 2 mentions the'' Alum Bluff or Chipola 

marl" at Rock Bluff, but Dall 3 was the first to correctly interpret the Alum Bluff section. He 4 was 

also the first to recognize the Oak Grove sand and 

to suspect the presence of the Alum Bluff in the 

vicinity of De Funiak Springs, about 10 miles southwest of the now classic Shoal River fossi1loca1.ities in 

Walton County. Vaughan, however, established the 

"Shoal River marl member" as a distinct subdivision 

of the Alum Bluff. His type section ~of the Shoal 

River, at Shell Bluff, was first published by Matson 

and Clapp.5 

Later work by the author has shown that the 

Shoal River fauna is present not only in the "Shoal 

River 1narl member," as defined by Matson and 

1 Langdon, D. W., jr., Some Florida Miocene: Am. Jour. Sci., 3d ser., vol. 38, 

p. 322, 1889. 2 Johnson, L. C., The Chattahoochee embayment: Geol. Soc. America Bull., 

vol. 3, p. 129, 1892. 3 Dall, W. H., Correlation papers; Neocene: U. S. Geol. Survey Bull. 84, p. 

122, 1892. 

• Dall, W. H., and Stanley-Brown, Joseph, Cenozoic geology along the Apalachicola River: Geol. Soc. America Bull., vol. 5, p. 166, 1894. 5 Matson, G. C., and Clapp, F. G., A preliminary report on the geology of Florida 

with special reference to the stratigraphy: Florida Geol. Survey Second Ann. 

Rept., p. 105, 1909. 

others, but in underlying and overlying sands and 

c1ays and that, although the "Shoal River marl 

member" can not be identified by its lithology over 

great dist-ances, the Shoal River fauna is readily distinguishable over a large area. In the type section 

at Shell Bluff, just cited, layers 3 to 7 are included 

in the Shoal River formation as here defined. A 

similar condition exists with regard to the Chipola 

fauna, which is not only present in the " Chipola 

marl member" as defined by Matson and others but 

in overlying sands and clays. Although there is no 

known section where the three faunas (Chipola, Oak 

Grove, and Shoal River) are present, there is no 

question that the Oak Grove fauna is intermediate 

between the Chipola fauna and the Shoal River 

fauna. ·In this report, therefore, the term Shoal 

River formation is applied to the marls, sands, and 

clays that occur stratigraphically between the top 

of the Oak Grove sand and the base of the Choctawhatchee marl, and the term Chipola formation is 

applied to the marls, sands, and clays that occur 

stratigraphically between the base of the Oak Grove 

sand and the top of the Chattahoochee formation. 

The definition of the Oak Grove sand is not herein 

modified, but its rank is changed from that of a member to that of a formation. 

The name Alum Bluff is perhaps unfortunate, for 

only the lower part of the Alum Bluff group, as it is now 

~nderstood, or the Chipola formation of this report, 

Is present in the type section, where it is overlain by 

the Choctawhatchee marl. The obscure stratigraphic 

and lithologic relationships of the deposits probably 

account for the fact that their formational rank and 

the tripartite character of their fauna were not established until1909.6 

The study of the fauna and flora of the Alum 

Bluff deposits has, from the first, yielded gratifying 

results. The later paleontologists have been peculiarly fortunate in that they have been able to build 

upon Dall's "Tertiary fauna of Florida," a work 

extraordinarily comprehensive for a pioneer investigation, with descriptions and figures so adequate that 

there is rarely any question of the characters of a 

given species. Since that time Miss Maury 7 has 

added a large number of species to the Chipola and 

o Matson, G. C., and Clapp, F. G., op. cit., p. 91, 1909. 

7 Maury, C. J., New Oligocene shells from Florida: BulL Am. Paleontology, 

vol. 4, No. 21, 1910. 

1 
2 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Oak Grove faunas, and Mr. Truman H. Aldrich, in 

a number of scattered papers, has greatly increased 

the knowledge of the rather neglected Shoal River 

fauna. Two relatively recent papers should be mentioned in even this cursory introduction-the short 

but significant discussion by Vaughan and Cooke 8 

of the Hawthorn formation and the comprehensive 

study by Berry 9 of the flora of the Alum Bluff. 

The interest of the present investigation lies not in 

the large number of 821 species considered but in the 

material which they furnish for comparison with 

other Tertiary faunas and for deductions upon the 

temperature, depth of the water, shore conditions, 

and all the factors that contributed to the early 

Miocene ecology. 

The Alum Bluff is here raised to the rank of a 

group not merely because the faunal differences 

between its subdivisions are too great to be included 

within a single formational unit but because of the 

implied significance of the shifting in the strand line 

and ocean currents necessary to bring about so marked 

a change in the life. Perhaps the most surprising 

and the most obvious result of a critical examination 

of the 1-Iollusca of the Alum Bluff is the .,marked 

individuality of each of the three faunas involved. 

The large number of peculiar species will doubtless be 

reduced by continued collecting, but there will remain 

a decided difference in the general make-up of the 

faunas coincident with certain changes in depth and 

temperature and the invasion of life from other areas. 

The Chipola fauna is a subtropical assemblage, 

typical of a region decidedly warmer than that 

inhabited by either of the other two faunas; it is 

relatively richer in species and not so rich in individuals. Of the 439 species which have been recognized from this formation three out of four are peculiar 

to it. Among the outstanding features may be 

mentioned the predominance of the gastropods, 

particularly of the turritids, the abundance of the 

bizarre and consequently short-lived and diagnostic 

Orthaulax gabbi, the diversity of the Areas and Cardiums, and the absence of any conspicuously dominant species of these genera, as in the Oak Grove and 

Shoal River. Apparently the Chipola was laid down 

in a period of unstable equilibrium. A number of 

new lines of development were being tried and this 

together with the favorable living conditions produced a much diversified fauna. However, in the 

''Sopchoppy limestone," which is nothing more than 

a very shallow-water phase of the Chipola, only 

about 50 species have been recognized, of which the 

only common forms are large Ostreas and Pectens 

and Anomias, an assemblage that is characteristic 

of oyster reefs. 

s Vaughan, T. W., and Cooke, C. W., Correlation of the Hawthorn formation: 

Washington Acad. Sci. Jour., vol. 4, pp. 250-253, 1914. 

~Berry, E. W., The•physical conditions and age indicated by the flora of the 

Alum Blu:tf formation: U. S. GeoL Survey Prof. Paper 98, 1916. 

In the fauna of the grayish-green Oak Grove sand 

there is a foreshadowing of the radical fall in temperature at the close of the Alum Bluff epoch which 

permitted the Mollusca of the Maryland province to 

penetrate the Floridian waters and to continue to 

exist for a short time in this new environment. The 

number of species in the Oak Grove is less than half 

the number recognized in the Chipola, but the number 

of individuals is much greater. The large fulguroids 

were apparently quite common and also a Pecten 

(Chlamys) closely allied toP. (Chlamys) madisonius 

Conrad, of the Maryland Miocene. The conspicuously abundant and ubiquitous species, however, 

include a new Strombus, Turritella alcida Dall, Glycymeris dry·manos Gardner, Diluvarca dodona (Dall), 

Cardium taphri,um Dall, Parvilucina piluliformis Dall, 

Chione glyptocyma Dall, and Spisula densa Dall. 

Any one of these species might well be selected as 

characteristic of the Oak Grove fauna. They are 

all newcomers and, except Cardium taphrium (Dall), 

which is rare in the Shoal River, no trace of them has 

been detected in any later formation. They were 

extraordinarily well adapted to Oak Grove conditions 

but were too highly modified to change with the changing environment. 

The Shoal River fauna is more complex than that 

of either the Chipola or the Oak Grove and shares 

some of the characters of both. The number of 

species is slightly increased, and several of then1, 

such as Conus waltonensis Aldrich, a new Cancellaria 

and Turritella, and Glycymeris waltonensis Gardner 

are as prolific as the abundant species in the Oak 

Grove. Apparently the waters continued to be 

relatively cool, for Astarte, which occurs chiefly in 

northern and temperate waters, is represented by 

three species, whereas in the Oak Grove there is only 

one and in the Chipola none at all. On the other 

hand, the southern element did not submit without 

a struggle. The West Indian assemblage is suggested 

by such forms as Spondylus sp. cf. S. bostrychites 

Guppy and the diversity of the Cancellarias. Temperatures were not yet so unfavorable as to shut out 

entirely the vigorous southern fauna, but the northern 

invaders were becoming increasingly more numerous. 

It is probable that there was a gradual emergence of 

the land from the close of the Chipola to the close of 

the Shoal River. Although none of the Alum Bluft 

faunas are in any sense of the word deep-water faunas, 

the Shoal River includes a larger number of characteristic littoral and between-tide genera than either 

of the other two. 

The most powerful factors in determining the evolution of the Alum Bluff faunas were probably the 

falling temperature of the sea water, the gradual 

subsidence of the sea, the probable shifting of the 

ocean currents and the consequent invasion of faunas 

from other· provinces, and the time element, which 

permitted all these causes to become potent. 
U. S. GEOLOGICAL SURVEY PRO~ONAL PAPER 14: PLATE I 

A M 

E 0 R G· I 

G u L F 0 F E X I c 0 

0 

MAP OF NORTHERN AND WESTERN FLORIDA 

Showing principal fossiliferous localities of the Alum Bluff group · 

Numbers are U. S. Geological Survey station numbers 

10 0 10 20 30 40 50 Miles 

867196 0-60 (l!'ace page 2) 142-A 

• 
PRIONODESMACEA AND ANOMALODESMACEA 3 

DISTRIBUTION OF THE FAUNA 

The following list shows the localities cited by 

number in the text and tables: 

75. 6 miles west of Gainesville, Alachua County, Fla. 

322b. Nigger Sink, 8 miles north of N ewmansville, Alachua 

County, Fla. 

323. Near Hawthorn, Alachua County, Fla. 

356. Sullivan's field, Levy County, Fla. 

359. Chimney Rock Quarry, haJf a mile north of Gainesville, 

Alachua County Fla. 

360. Preston's marl bed, 3~ miles north of Waldo, Alachua 

County, Fla. 

361. Hogtown Creek, at old mill 2 miles northwest of Gainesville, Alachua County, Fla. 

365. Johnsons Sink, 4 miles northwest of Hawthorn, Levy 

County, Fla. 

369. Hammock west of Magnesia Springs, near Hawthorn, 

Alachua County, Fla. 

373. Phosphate rock of the Devil's Mill Hopper, 5 miles 

northwest of Gainesville, Alachua County, Fla. 

395. 50-foot well in Tallahassee, Leon County, Fla. 

2116. Lapenotiere's Hammock, on Sixmile Creek, 1~ miles 

south of Orient Station, Hillsborough County, Fla. 

2211. Lower bed, Alum Bluff, Liberty County, Fla. 

2212. Tenmile Creek, 1 mile west of Baileys Ferry, Calhoun 

County, Fla. 

2213. 1 mile below Baileys Ferry, Chif>ola River, Calhoun 

County, Fla. 

2214. Tenmile Creek, 1 mile west of Baileys Ferry, Calhoun 

County, Fla. 

2238. Flournoy's mill race, 2 miles east of Argyle, Walton 

County, Fla. 

2302. 2 miles west of Tallahassee, Leon County, Fla. 

2322. Sopchoppy Creek, Wakulla County, .Fla. 

2324. White Sulphur Springs (White Springs), Suwannee 

River, Hamilton County, Fla. 

2380. Clay Springs, Orange County, Fla. 

2564. McClelland farm, 1 mile below Baileys Ferry, Calhoun 

County, Fla. 

2566. Upper bed at Rock Bluff, Apalachicola River, Liberty 

County, Fla. 

2568. Lower or "Chipola" bed at Alum Bluff, Apalachicola 

River, Liberty County, Fla. 

2611. West bank of Suwannee River, SW. M NW. M SE. M sec. 8, T. 4 S., R. 11 E., near Dell, Lafayette County, and 15 

miles south of Ellaville, Madison County, Fla. 

~ 2612. West bank of Suwannee River just below a sulphur 

spring 2~ miles below 2611, Lafayette County, 17 miles south 

of Ellaville, Madison County, Fla. 

2645. McClellan farm, Shoal River, 5 miles west of Mossyhead, Walton County, Fla. 

2646. Oak Grove, Yellow River, Okaloosa County, Fla. 

2652. Horse Creek, 1~ miles south of Oak Grove, Okaloosa 

County, Fla. 

2653. "Otaheite beds," on east Blackwater Creek, 15 miles 

west of Oak Grove, Okaloosa County, Fla. 

2675. 1 mile south of railroad bridge at Milligan, Okaloosa 

County, Fla. 

2823. West bank of Suwannee River just below sulphur 

spring 2~ miles below 2612, 19~ miles south of Ellaville, 

Madison County, Fla. 

2868. Fuller's earth bed, Quincy, Gadsden County, Fla. 

3173. "Fuller's earth" mines of Chesebrough Co., Quincy, 

Gadsden County, Fla. 

3385. Gastropod Gulch, 4 miles southeast of Bainbridge, 

Decatur County, Ga. 

3386. Roseland Plantation, 3~ miles southeast of Bainbridge, Decatur County, Ga. 

3396. Sam Dickens's field, 7 miles southeast of Bainbridge, 

Decatur County, Ga. 

3415. "Rock Bluff," east bank of Apalachicola River, 12 

miles below railroad, Liberty County, Fla. 

3417. Alum Bluff, 35 miles below railroad bridge over 

Apalachicola River, Liberty County, Fla. 

3419. McClelland farm 1 mile below Baileys Ferry, Calhoun 

County, Fla. 

3424. J. C. Henderson's well, western limits of Tallahassee, 

Leon County, Fla. 

3704. Quincy, Gadsden County, Fla. 

3731. Near Mos~yhead, sec. 6, T. 3 N., R. 21 W., Walton 

County, Fla. 

3732. Dave Adams Mill Creek, sec. 2, T. 3 N., R. 21 W., 

Walton County, Fla. 

3733. Three-fourths mile west of Shell Bluff, Shoal River, 

Walton County, Fla. 

3742. Shell Bluff, Shoal River, Walton County, Fla. 

3747. 8 miles south of Lake DeFuniak, Walton County, Fla. 

37 48. Summerville mill race, 1 mile east of Argyle, Walton 

County, Fla. 

3749. Allen Senterfeit's mill, 3 or 4 miles north of Campton, 

Walton County, Fla. 

3856. 6 miles west-northwest of Mossyhead, Walton County, 

Fla. 

4966. 1,000 feet above Georgia, Florida & Alabama Railroad 

bridge over Ochlockonee River, WakulJa County, Fla. 

4976. White Springs, Hamilton County, Fla. 

4977. W. C. Rose's farm, West Sopchoppy, Wakulla County, 

Fla. 

4978. Rose's Mill Creek, 3 miles west of Sopchoppy, Wakulla 

County, Fla. 

4986. Miller's quarry, 1 mile from Ellenton, Manatee County, 

Fla. 

4991. Ochlockonee River, 1 mile north of Holland, Loon 

County, Fla. 

5079. One-half mile below Shell Bluff, Shoal River, Walton 

County ,Fla. 

5080. First ravine below Shell Bluff, Shoal River, Walton 

County, Fla. 

5184. First ravine below Shell Bluff, Shoal River, Walton 

County, Fla. 

5192. Folk's Creek, 4 miles south of Argyle, Walton County, 

Fla. 

5193. Crowder's Crossing, 172 miles below Shell Bluff, Shoal 

River, Walton County, Fla. 

5194. 1!.-2 miles below Shell Bluff, Shoal River, Walton 

County, Fla. 

5195. First ravine below Shell Bluff, Shoal River, Walton 

County, Fla. 

5613. Coronet phosphate mine, 5 miles southeast of Plant 

City, Hillsborough County, Fla. 

5618. 3~ miles southwest of De Funiak Springs, Walton 

County, Fla. 

5629. Coronet phosphate mine, 5 miles southwest of Plant 

Citv, Hi11sborough County, Fla. 

5.630. 100 yards below Oak Grove Bridge, Yellow River, 

Okaloosa County, Fla. 

5631. Oak Grove Bridge, Yellow River, Okaloosa County, }"'la. 

5632. Oak Grove, Yellow River, Okaloosa County, Fla. 

5633. Oak Grove, Yellow River, Okaloosa County, Fla. 

6175. Left bank of Suwannee River three-fourths mile above 

White Springs, Columbia County, Fla. 

6196. Rock stratum lying immediately above fuller's earth 

at Ellenton, Manatee County, Fla. 
4 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

6197. Limestone underlying fuller's earth at Ellenton, 

Manatee County, Fla. 

6208. Marl underlying phosphate of Pierce Phosphate Co., 

Pierce, Polk County, Fla. 

6209. 272 miles southwest of Phosphate Mining Co.'s pit No. 

4, Mulberry, Polk County, Fla. 

6769. East bank of Suwannee River at wagon bridge at White 

Springs, Hamilton County, Fla. 

6775. Spring on left bank of Suwannee River about 100 yards 

above Rock Island and about half a mile above White Springs, 

Columbia County, Fla. 

6776. Spring on left bank of Suwannee River about 100 

yards above Rock Island and about half a mile above White 

Springs, Columbia County, Fla. 

6778. Spring on left bank of Suwannee River about 100 

yards above Rock Island and about half a mile above White 

Springs, Columbia County, Fla. 

6783. Langston's Sink, about 4 miles northwest of Lake 

City, on road to White Springs, CoJumbia County, Fla. 

6800. Preston Sink, 3 miles north of Waldo, Alachua County, 

Fla. 

6801. Lochloosa Creek, near Magnesia Spring, about 3 miles 

west of Hawthorn, Alachua County, Fla. 

7054. 400 feet below bridge, Oak Grove, Okaloosa County, 

Fla. 

7055. Old Senterfeit mill, 4~ miles southwest of Laurel 

Hill, Walton County, Fla. 

7148. Gastropod Gulch, 5~ miles southeast of Bainbridge, 

Decatur County, Ga. 

7151. Tenmile Creek, Calhoun County, Fla. 

7183. Alum Bluff (lower bed), Liberty County, Fla. 

7256. Look and Tremble Shoals, Chipola River, Calhoun 

County, Fla. 

7257. Sexton's marl bed, sec. 11, T. 1 N., R. 10 W., Tenmile 

Creek, Calhoun County, Fla. 

7261. Upper Alaqua Lethu (?) Bluff, near De Funiak 

Springs, Walton County, Fla. 

7264. De Funiak Cardium beds, Alaqua, Walton County, 

Fla. 

7 468. Sopchoppy, Wakulla County, Fla. 

7847. Lake Butler, Bradford County, Fla. 

7893. Boynton Landing, Choctawhatchee River, Washington County, Fla. 

9957. Gully south of the road and east of the bridge over 

White's Creek, on road from Eucheeanna to Knox Hill, 6.7 

miles south of Argyle, 1. 7 miles southeast of Eucheeanna, 

Walton County, Fla. 

9958. Site of Flournoy's old mill, about 1.7-i miles northeast 

of Argyle, Walton County, Fla. 

9959. One-fourth mile west by north of Pleasant Ridge 

Church, 5.2 miles southwest of De Funiak Springs, Walton 

County, Fla. 

9960. Folk's Creek, sec. 21 or 22, T. 3 N., R. 18 W., 6 miles 

south of Argyle and 1.7 miles from Eucheeanna, Walton County, 

Fla. 

9961. Horse Creek, 1~ miles south of Oak Grove, Okaloosa County, Fla. 

9994. John M. P. McClelland's farm, Chipola River, Calhoun County, Fla. 

10596. Waldon Bridge over Bruce Creek, 5 miles west of 

Red Bay, Walton County, Fla. 

10603. Gully south of the road and east of the bridge over 

White's Creek, on road from Eucheeanna to Knox Hill, 6. 7 miles 

south of Argyle, 1.7 miles southeast of Eucheeanna, Walton 

County, Fla. 

10608. White's Creek, half a mile below bridge on Eucheeanna-Knox Hill road, Walton County, Fla. 

10609. The Woodyard, three-fourths mile above ShellLitnding, Holmes Creek, Washington County, Fla. (lower bed). 

10610. The Woodyard, three-fourths mile above Shell Landing, Holmes Creek, Washington County, Fla. (upper limestone.) 

10611. White's Creek near water's edge, half a mile below 

bridge over creek on road from Eucheeanna to Knox Hill, 

6.7 miles south of Argyle, 1.7 miles southeast of Eucheeanna, 

·walton County, Fla. 

10612. Chester Spence's farm, 5 miles southwest of De 

Funiak Springs, at head of Sconter's Mill Creek, Walton 

County, Fla. 

10658. Shell Bluff, Shoal River, 6 miles west-northwest of 

Mossyhead, Walton County, Fla. 

10659. Tanner's mill (Old Senterfeit mill), 4 miles southwest of Laurel Hill, Okaloosa County, Fla. 

10660. Lower bed, Alum Bluff, Liberty County, Fla. 

10661. Godwin Bridge over Shoal River, 5 to 6 miles northwest of Mossyhead, Walton County, Fla. 

10662. Lower bed, Shoal River, between Godwin Bridge and 

Shell Bluff, 5 to 6 miles west-northwest of Mossyhead, Walton 

County, Fla. 

10663. Crowder's Crossing, 1~ miles below Shell Bluff, 

Shoal River, Walton County, Fla. 

10860. Boynton Landing, 4 miles east of Miller's Ferry, 

Washington County, Fla. 

10869. Folk's Creek, 6 miles south of Argyle, Walton County, 

Fla. 
PRIONODESMACEA AND ANOMALODESMACEA 5 

Local distribution of species of Prionodesmacea and A. nomalodesmacea 

[pr, Prolific; a, abundant; c, common; p, present; r, rare (not more than half a dozen individuals). The localities are arranged in geographic succession from north to south and from west to east within each formation. A few of the peninsular localities are not included.] 

ooo,.u.-~ Oak Florida-Chipola formation Grove 

sand 

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________________________________________________ --- _________ •• 

proteracuta dys- I 

takta Gardner, · n. subsp ___________________________ p ___ r ______ r p p p __________________ , _____________________________________________________________ _ 

proteracuta leita \ Gardner,n.subsp ______ -- __________ p ___ --- _____ p a a a p c ____________ , _____________________ --- ___ --- --- ------ --- --- -----------------

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diphya Gardner, n. 

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: : : : : : I 356, Sullivan's Field
PRIONODESMACEA AND ANOMALODESMACEA 7 

Lo('al distribution of species of Prionodesmacea and Anomalodesmacea-Continued 

Florida-Oak Grove sand Florida-Shoal River formation 

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8 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

SYSTEMATIC DESCRIPTIONS 

Phylum MOLLUSCA 

Class PELECYPODA 

Order PRIONODESMACEA 

Section TAXODONTA 

Superfamily NUCULACEA 

Family NUCULIDAE 

Genus NUCULA Lamarck 

1799. N ucula Lamarck, Prodrome d'une nouvelle classification 

des coquilles: Soc. hist. nat. Paris Mem., p. 87. 

Type: Area nucleus Linnaeus. (Recent off the 

European coast from the Faroe Islands to the Aegean 

Sea; Pliocene of England and southern Europe.) 

Shell nacreous, small, trigonal to subcircular or elliptical; un1bones subcentral or posterior; two series of 

transverse, numerous and close-set hinge teeth, separated by a triangular chondrophore; surface generally 

smooth or concentrically striated; margins simple or 

crenulate; adductor impressions subequal, two in 

number; pallial line simple. 

Nucula is represented i.r;1 the Alum Bluff group of 

Florida, as at so many other horizons and areas, by 

a few common species. Each horizon has its own 

characteristic member of the group. There is but the 

single Nucula in the Oak Grove sand-Nucula sinaria 

Dall-a variable and prolific species that is restricted 

to the single horizon. Nucula chipolana Dall is almost 

equally abundant at the horizon which it characterizes. The subspecies which occurs in the Shoal River 

formation is less common and is replaced in the 

environs of De Funiak Springs by a larger formNucula defuniak Gardner, n. sp. The fifth speciesNucula dasa Gardner, n. sp.-has been found only at 

the type locality in the Chipola formation on Choctawhatchee River. 

The distribution of the genus in the Alum Bluff 

bears much the same relationship to its occurrence in 

Miocene deposits to the north and south as does the 

distribution of Nucula in the Recent seas. In the 

early Miocene, as in Recent times along the Atlantic 

coast north of Hatteras, the individuals were large and 

increasingly abundant toward the north. The Florida 

species are very much smaller but still abundant, 

whereas Nucula tenuisculpta Gabb, which is characteristic of the Miocene West Indian faunas, is very small 

and never common. 

The genus has survived from the middle Paleozoic ' possibly because of its rernarkable adaptability. It is 

found in both shallow and deep water and on both 

sandy and muddy bottoms. Though characteristic of 

the boreal and temperate oceans the group has also 

a meager representation in the tropical seas. 

Shell conspicuously thin: 

Altitude of adult shell rarely exceeding 3 millimeters. 

Nucula chipolana Dall. 

Altitude of adult shell usually exceeding 3 millimeters. 

Nucula chipolana waltonia Gardner, n. subsp. 

Shell heavy : 

Escutcheon aepressed, not radially striated: 

Umbones low __________________ Nucula sinaria Dall. 

Umbones moderately tumid and elevated. 

Nucula dasa Gardner, n. sp. 

Escutcheon not depressed, radially striate. 

N ucula defuniak Gardner, n. sp. 

N ucula chipolana Dall 

Plate II, Figure 1 

1898. Nucula chipolana Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 575, pl. 32, fig. 10. 

Dall describes this species as follows: 

Shell small, solid, polished, with faint radial striae more conspicuous ventrally, and more or less obvious incremental lines; 

beaks turgid, low; posterior end of shell obliquely truncate, 

flattish; base arcuate, anterior dorsal line sloping, anterior end 

attenuated and rounded; there is no defined lunule; the 

escutcheon is elongate-cordate, ill-defined, the margins in the 

middle line slightly pouting; internally polished, hardly pearly, 

with the basal margin finely sharply crenulate; the chondrophore small, narrow, and very oblique, anteriorly directed; 

anterior teeth narrow, slender, about thirteen; posterior teeth 

four or five. Longitude of shell, 4 millimeters; altitude, 2.75 

millimeters; diameter, 2.0 millimeters. 

The chief characteristics of this small species are its elongated 

form and fine radial striae. 

Type: u: S. Nat. Mus. No. 136098. 

Type locality: No. 2564, McClelland farm, 1 mile 

below Baileys Ferry, Calhoun County, ·Fla. 

The species, broadly considered, is thinner shelled 

and more compressed than any of the other Alum 

Bluff forms, though this character is less marked at 

Alum Bluff than on Chipola River. The range of 

variation in outline is comparable to that of Nucula 

sinaria from Oak Grove, although the average individual from Oak Grove is larger and higher than that 

from Chipola River and Alum Bluff. The forms 

referred to the subspecies waltonia ar-e also a little 

larger than chipolana s. s. and relatively higher, but 

the thinner shell and more delicate hinge are sufficient 

to separate them from sinaria. Then, too, the 

escutcheon of sinaria is slightly sunken and not 

merely flattened as in chipolana s. 1. In Nucula dasa 

from the Chipola formation on Choctawhatchee River 

the shell is very heavy and rather inflated and the 

escutcheon is depressed. 

Nucula chipolana Dall is abundant at the horizo-n 

which it characterizes. 

Occurrence: Chipola formation, localities 10609P, 

10610P, 7257°, 2213Pr, 2564°, 3419a, 7151a, 2211a, 7183c. 

Shoal River formation, locality 10661P.10 

Nucula chipolana waltonia Gardner, n. subsp. 

Plate II, Figures 2-3 

Shell of moderate dimensions for the genus, thin and 

rather compressed. Umbones small, obtuse, opisthogyrate, posterior in position. Umbonal angle not far 

1o pr, Prolific; a, abundant; c, common; p, present; r, rare (not more than half a 

dozen individuals). 
PRIONOD-ESMACEA AND ANOMALODESMACEA 9 

from 90°. Anterior dorsal margin feebly convex, 

much more produced than the obliquely truncate 

posterior slope. Basal n1argin asymmetrically arcuate, 

more strongly upcurved behind than in front. Lunule 

not sharply delimited, indicated by the flattening of 

the shell. Escutcheon narrow; elongate, cordate, 

flattened but not depressed. A subcutaneous radial· 

sculpture developed, usually obsolete in the ·umbonal 

region but fine and regular toward the base, where the 

sulci number about 12 to the millimeter and are 

separated by flat interradials that are more than 

double their own width. Basal margin finely serrate 

in harmony with the radials. Concentric sculpture 

restricted to grayish color bandings and obscure resting stages. Ligament entirely internal, lodged in a 

small cuneiform resilium rudely parallel to the anterior 

dorsal margin. Hinge rather delicate. Teeth taxodon t, arranged in two discrete series, the posterior 

including six in the type, the anterior three times as 

many. The half dozen umbonal teeth in the anterior 

series exceedingly small and crowded, the medial 

teeth in both the anterior and posterior series slender 

but well eJevated. Muscle impressions and pallial 

line very obscure because of the thinness of the shell. 

Dimensions: Altitude, 3.2 millimeters; latitude, 4.0 

millimeters; semi diameter, 1.2 millimeters. 

Type: U. S. Nat. Mus. No. 352288. 

Type locality: No. 3742, Shell Bluff, Shoal River, 

Walton County, Fla. 

The Shoal River species is larger than that from the 

Chipola and relatively higher. The radial sculpture 

is commonly a little stronger and more persistent 

in the umbonal region, but this is not a constant 

character. 

Occurrence: Shoal River formation, localities 3856P, 

2645P, 3742c, 10658r, 2238P, 9957r. 

Nucula sinaria Dall 

Plate II, Figure 4 

1898. N ucula sinaria Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 575, pl. 32, fig. 7. 

Dall describes this species as follows: 

Shell small, solid, trigonal, polished, with fine radial striae, 

more distinct near the basal margins, and faint, concentric, 

rather irregular furrows, obsolete over most of the valve but 

tending to be stronger near the anterior and posterior slopes; 

here and there one crosses the whole shell like the indication of a 

resting stage; dorsal slopes nearly straight, base arcuate, ends 

rounded; lunule absent, escutcheon impressed; striated, the 

margins not pouting in the middle; beaks prominent, obtuse; 

interior brilliantly pearly, muscular impressions deep; the basal 

margin finely crenulate; hinge strong, wide; the chondrophore 

oblique, heavy; anterior teeth wide, strong, about seventeen, 

posterior about seven. Longitude of shell, 4.75 millimeters; 

altitude, 4 millimeters; diameter, 2.5 millimeters. 

This species differs from the preceding (N ucula chipolana 

Dall) by its more trigonal, heavy, and pearly shell, its wider and 

proportionately heavier hinge, and its impressed instead of 

merely flattened escutcheon. 

Type: U.S. Nat. Mus. No. 135820. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

Nucula sinaria Dall exhibits a remarkable range of 

variation in dimensions and relative proportions. The 

type is larger, n1uch higher, and more trigonal than the 

average individual from Oak Grove. The differences 

in the peripheral members are sufficiently great to be 

given subspecific rank, but as they are apparently of 

no stratigraphic or geographic significance there is 

little to be gained by splitting the series. The depressed escutcheon is a character shared by only one 

other Alum Bluff species, Nucula dasa, from the 

Chipola formation on Choctawhatchee River. The 

Chipola species is usually lower and heavier than N. 

sinaria and is more inflated in the umbonal region. 

Occurrence: Oak Grove sand, localities 2646 pr,. 

5632 a, 5631 c, 5633 c, 7054 c, 9961 °1 10659 °. 

Nucula dasa Gardner n. sp. 

Plate II, Figures 5-7 

Shell highly polished, small, heavy, quite strongly 

inflated. Umbones quite prominent, obtuse, flattened 

upon their summits, opisthogyrate, set well within the 

posterior third. Umbonal angle not far from 90°. 

Posterior dorsal slope very steep. Anterior rather 

gentle and feebly arcuate. Basal margin more sharply 

upcurved in front than behind. Lunule narrow, 

elongated, not sharply delimited but defined by the 

flattening of the shell and by the darker coloring of the 

lunular area. Escutcheon rather narrow, cordate, 

feebly depressed, the depression emphasized by the 

slightly raised margins. Radial sculpture restricted 

to exceedingly fine lines, least faint near the base but 

commonly obscured even there by the surface glaze. 

Basal margin finely but sharply serrate. Concentric 

striae also very faint. Resting stages rarely developed. 

Ligament internal, lodged in a very small cuneiform 

resilium elongated parallel to the anterior dorsal 

margin. Hinge dentition strong and heavy. Teeth 

taxodont, arranged in two discrete series,, the anterior 

series in the type including 15, the posterior 7, the 

half dozen nearest the umbones in the anterior series 

very fine and crowded, the posterior teeth and, more 

especially, the anterior teet~ away from the umbones, 

elevated, compressed, curved slightly to:ward the d<?rsal 

margins but not hooked. Muscle impression and 

pallial line usually very obscure because of the highly 

polished inner surface. Anterior scar placed well 

down toward the base at the distal extremity of the 

hinge, larger, less rounded, and more ventral in 

position than the posterior scar. Pallial line simple, 

moderately near to the basal margin. 

Dimensions: Altitude, 3.2 milli1neters; latitude 1 

3.55 millimeters; semidiameter, 1.5 millimeters. 

Type: U.S. Nat. Mus. No. 352289. 

Type locality: No. 7893, Boynton Landing, Choctawhatchee River, Washington County, Fla. 
10 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Nucula da'sa Gardner, n. sp., is the heaviest.and most 

inflated species known from the Alum Bluff. In these 

characters it is contrasted sharply with the coexistent 

N. chipolana Dall, which is the thinnest and the most 

compressed. N. dasa shares with N. sinaria the 

sunken escutcheon, but the shell is less inflated in the 

Oak Grove species and the umbones less prominent. 

Nucula dasa is known only from the type locality. 

Occurrence: Chipola formation, locality 7893P. 

Nucula defuniak Gardner, n. sp. 

Plat'e II, Figures 8-10 

Shell of moderate dimensions for the group, not very 

strongly inflated in the umbonal region and compressed 

toward the ventral margins, rounded, trigonal in outline. Umbonal angle obtuse, not quite 90°. Unlbones very small, opisthogyrate, posterior in position. 

Posterior dorsal slope consequently steeper than the 

anterior. Ventral margin asymmetrically arcuate, 

more strongly upcurved behind than in front. Lunule 

not defined, indicated by the flattening of the valves 

over a lenticular area, a slight darkening of the shell, 

and the closer radials. Escutcheon obscurely defined, 

cordate, flattened but not sunken, the shell substance 

darker as in the lunular area and the radials closer and 

stronger. Radial sculpture developed in the form of 

subcutaneous linear sulci, least faint toward the ventral margins, numbering 10 or 12 to the millimeter, and 

near the margin of the adult separated by flat interspaces of more than double their own width. Ventral 

margin finely crenate in harmony with the radials. 

Lunule sculptured with about 9 slightly wider radials 

separated by relatively narrow interspaces, the sculptured area cut off from the central portion of the shell 

and from the margin, which is microscopically serrated by the radials. Concentric sculpture restricted 

to an obscure color banding and a few ill-defined resting stages. Ligament internal, lodged in a narrow, 

cuneate, anteriorly directed resilium. Teeth arranged 

in two discrete series, 13 in number in the anterior 

series of the type, 7 in the posterior, the teeth shorter 

toward the umbones, especially in the anterior series, 

the medial teeth in each series very long and hooked, 

the hooks turned toward the dorsal margins. Muscle 

impressions placed at the extremities of the dental 

series, obscure, the anterior relatively higher and narrower than the posterior. Pallial line simple, distinct, 

distant from the basal margin. Inner margins in 

many specimens radially striate almost to the pallial 

line. 

Dimensions: Altitude, 4.3 millimeters; latitude, 5.0 

millimeters; semi diameter, 1. 7 millimeters. 

Type: U. S. Nat. Mus. No. 352290. 

Type locality: No. 5618, 3Y2 miles southwest of De 

Funiak Springs, Walton County, Fla. 

Nucula defuniak is very close to the type of N. 

sinaria in dimensions and outline but stands apart 

from that species and from all the oilller Alum Bluff 

forms by reason of the radial sculpture upon the escutcheon. 

The teeth in the anterior series of larger but less 

perfect individuals number as high as 18. 

The species is best represented in the environs of 

its type locality. 

Occurrence: Shoal River formation, localities 3856r, 

5079P, 9958r, 3748°, 3747°1 7261P, 7264P, 9960°1 9957r, 

10603°, 5618°, 9959P. 

Family LEDIDAE 

Genus LEDA Schumacher 

1817. Leda Schumacher, Essai d'un nouveau systeme des habitations des vers testaces, pp. 55, 172. 

Type: Arcarostrata Gmelin--Leda pernula (MUller). 

(Recent in the North Atlantic.) 

Shell solid, porcellaneous, transversely elongate, 

rounded anteriorly, more or less rostrate posteriorly; 

beaks proximate, commonly tumid, feebly opisthogyrate; exterior surface concentrically sculptured; hinge 

armature taxodont, the teeth arranged in an anterior 

and a posterior series; chondrophore subumbonal, 

trigonal; pallial line interrupted by a shallow sinus 

corresponding to the short siphons of the animal; 

inner ventral margins simple. 

This genus also originated in the Paleozoic but in 

the Silurian, one period later than Nucula. The more 

than 80 living species have a wide geographic and 

bathymetric distribution, although the majority are 

boreal. Leda is conspicuously more abundant in the 

Miocene Floridian faunas than in those of the West 

Indies. 

The smaller Alum Bluff Ledas, dissimilar as are the 

peripheral species, show an astonishing gradation, 

which relates even such unlike forms as Leda canonica 

Dall and Leda diphya Gardner, n. sp. The genus is 

abundant in the Chipola formation, being represented 

by eight species. In the Oak Grove sand Leda is 

ren1arkably rare. There is a single species peculiar 

to the formation and two other species, each of them 

represented by a single imperfect individual, one of 

which has been tentatively referred to a Chipola form 

and the other ren1ains unnamed. A Shoal River Leda 

may be present at one locality. In the Shoal River 

formation the genus returns to prominence, though 

it is not quite so conspicuous at that horizon as it is 

in the Chipola. The three smaller Shoal River species 

are with one possible exception restricted in their range 

to the single horizon, though they have analogs in the 

Chipola faunas. The remarkable Leda bas'£lissa Gardner, n. sp., recalls Leda pharcida Dall of the Wilcox 

fauna. 

The relationship of the smaller Alum Bluff Ledas as 

indicated by the concentric sculpture may be expressed by the accompanying diagram. 
PRIONODESMACEA AND ANOMALODESMACEA 11 

Chipola formation 

L. diphya 

Oak Grove sand 

L. dodona // 

L. proteracuta dystakta 

Shoal River formation 

i 

L. prrteracuta.----~L. proteracuta leita L. polychoa defuniak~----L. polychoa 

// 

L. proteracuta diamesa 

1 L. le~talea '-\.L. acuta 

L. canonica meiopykna 

l 

L. canonica 

// 

L. leiorhyncha 

Concentric sculpture increasingly feeble laterally. 

The other characters-general outline, umbones, 

lunule, escutcheon, dentition, and muscle and mantle 

scars-vary but little. The Shoal River forms as a 

rule are larger than those from the Chipola and, on 

the whole, the more coarsely sculptured forms are 

more heavily built throughout. 

Latitude of adult exceeding 15.0 millimeters. 

Leda basilissa Gardner, n. sp. 

Latitude of adult not.exceeding 15.0 millimeters: 

Latitude of adult rarely exceeding 7.0 millimeters; concentric sculpture as a rule not conspicuously coarse and 

distant toward the umbones: 

Umbones broadly rounded: 

Concentric ridges more or less obtuse, rarely exceeding 30 in number: 

Concentric sculpture close and flattened over 

the entire surface ____ Leda? acuta Conrad. 

Concentric sculpture, if present, more or less 

elevated. 

Leda proteracuta Gardner, n. sp., s. l. 

Between 20 and 25 concentric ridges, 

most prominent medially, inclined to 

weaken and become obsolete laterally. 

Leda proteracuta Gardner, n. sp., s. s. 

Between 15 and 20 concentric ridges, 

relatively coarse and distant toward 

the umbones. 

Leda proterac'uta dystakta Gardner, n. subsp. 

Concentric sculpture obsolete except 

near the tips of the umbones and the 

ventral margin. 

Leda proteracuta leita Gardner, n. subsp. 

From 25 to 30 concentric ridges, as a 

rule, in many specimens irregularly 

spaced. 

Leda proteracuta diamesa Gardner, n. subsp. 

Concentric ridges commonly acute, exceeding 30 

in number in the adult: 

From 30 to 40 acute concentric ridges. 

Leda leptalea Gardner, n. sp. 

More than 40 obtuse or subacute concentric 

ridges __________ Leda canonica Dall, s. I. 

Concentric ridges exceedingly fine and 

closely crowded, 10 to 25 to the millimeter____ Leda canonica Dall, s. s. 

Between 40 and 50 concentric ridges. 

Leda canonica meiopykna Gardl)er, n. subsp. 

Umbones obliquely flattened: 

Concentric ridges rarely exceeding 40 and rarely 

altogether obsolete upon the rostrum: 

Concentric sculpture persistent upon the 

rostrum __ Leda polychoa Gardner, n. sp., s.l. 

Conceritric sculpture more or less obsolete 

upon the rostrum. 

· Leda polychoa deftmiak Gardner, n. subsp. 

Concentric ridges usually exceeding 40, altogether 

obsolete upon the rostrum. 

Leda leiorhyncha Gardner, n. sp. 

Latitude of adult usually exceeding 7.0 millimeters; concentric sculpture conspicuously coarse and distant toward 

the umbones: 

Concentric sculpture on the medial portion of the 

shell becoming abruptly finer and closer; escutcheon 

finely and regularly laminated. 

Leda diphya Gardner, n. sp. 

Concentric sculpture uniform in character over the 

entire medial portion of the shell; escutcheon smooth 

or irregularly laminated ________ Leda dodona Dall. 

Leda basilissa Gardner, n. sp. 

Plate II, Figures 11-12 

Shell very large, exceedingly brittle, compressed, 

transversely elongated, slightly produced and rostrate 

posteriorly. Umbonal angle very wide. Anterior 

dorsal margin gently declining, posterior feebly concave. Anterior lateral margin smoothly rounded but 

not bowed beyond the distal extremity of the dorsal 

margin. Posterior extremity probably obliquely truncate. Base line arcuate, more strongly upcurved in 

front than behind. Umbones swollen near their tips, 

slightly overtopping the dorsal margins, the tips 

proximate and feebly opisthogyrate. Lunule sublinear, depressed, extending almost but not quite to 

the lateral extremity, outer margin sha-rply elevated. 

Escutcheon narrow, lanceolate, concave, unequally 

divided by a sharply elevated line that cuts off an 
12 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

inner lanceolate area. Incrementals of the inner area 

rudely parallel to the dorsal margin, of the outer 

area oblique to it. External surface finely and regularly sculptured concentrically, the sharply elevated, 

somewhat laminar threads of the umbonal area 

developing away from the umbones into crowded 

lamellae ventrally overlapping, raised slightly toward 

the anterior dorsal margin, abruptly disappearing at 

the edge of the lunule, bent abruptly outward and 

slightly downward at the keel, slightly flexuous across 

the keel, disappearing abruptly at the edge of the 

escutcheon; interspaces decidedly wider than the 

laminae upon the rostrum, not so wide upon the disk. 

Ligament internal, the pit wide, trigonal, sunk deep 

beneath the umbones. Dental series somewhat concavo-convex. The anterior series arched upward 

toward the dorsal margin, including 33 to 38 teeth, 

those at the extremities of the series short and straight, 

the medial teeth elevated and >-shaped, the apex 

of the angle directed toward the umbone. Number 

in posterior series probably a little higher. Adductor 

and pallial scars obscure. 

Dimensions of left valve: Altitude, 14.3 millimeters; 

latitude, 32.0 ± millimeters; semidiameter 4.5 millimeters. Dimensions of right valve of a larger specinlen: Altitude, 17.0 millimeters; latitude 38.2 ± millimeters; semi diameter 5.0 millimeterS. 

Cotypes: U.S. Nat. Mus. No. 352291. 

Type locality: No. 3733, three-fourths of a mile 

west of Shell Bluff, Shoal River, Walton County, 

Fla. 

Leda basilissa Gardner, n. sp., is a descendant of the 

group of Leda pharcida Dall of the Wilcox fauna, a 

shell of similar outline but not so large; it is more 

elongated transversely and the characters of lunule 

and escutcheon are similar, but the surface is more 

sharply sculptured. 

The types are badly mutilated, but the shell is so 

unlike anything closely allied in time or space that it 

seems worth while to bring even the imperfect material 

to light. 

Occurrence: Shoal River formation, locality 373W. 

Leda acuta (Conrad) 

Plate II, Figures 13-16 

1832. Nucula acuta Conrad, American marine conchology, p. 

32, pl. 6, fig. 3. 

Not Nucula acuta Sowerby, Geol. Soc. London Trans., 

2d ser., vol. 5, pl. 39, fig. 5, 1837. 

1845. N ucula acuta Conrad, Fossils of the medial Tertiary of 

the United States, p. 57, pl. 30, fig. 2. 

1846. Nucula carinata H. C. Lea, Am. Philos. Soc. Trans., new 

ser.,. vol. 9, p. 244, pl. 24, fig. 28. 

1846. Nucula acutidens H. C. Lea, idem, p. 244, pl. 34, fig. 29. 

1857. Nucula acuta Say. Tuomey and Holmes, Pleiocene 

fossils of South Carolina, p. 53, pl. 17, figs. 10-12. 

1858. Leda acuta Emmons, North Carolina Geol. Survey Rept., 

p. 287, fig. 208 A. 

1860. ? N ucula acuta Holmes, Post-Pleiocene fossils of South 

Carolina, p. 16, pJ. 3, fig. 7. 

1862. Leda unca Gould, Boston Soc. Nat. Hist. Proc., vol. 8, 

p. 282. 

1863. Nuculana acuta Conrad, Acad. Nat. Sci. Philadelphia 

Proc. for 1862, p. 581. 

1863. Nuculana acutidens H. C. Lea. Conrad, idem, p. 581. 

1863. Nuculana carinata H. C. Lea. Conrad, idem, p. 581. 

1864. N uculana acuta Conrad. Meek, Check list of the ipvertebrate fossils of North America, Miocene, Smithsonian Miosc. Coli., vol. 7, No. 183, p. 5. (Name only.) 

1864. N uculana acutidens (H. C. Lea). Meek, idem, p. 5. 

(Name only.) 

1864. Nuculana carinata (H. C. Lea). Meek, idem, p. 5. 

1881. Leda jamaicensis D'Orbigny. Dall, Harvard Coli. Mus. 

Comp. Zoology Bull., vol. 9, p. 124. 

1882. Leda unca Gould. Verrill, Connecticut Acad. Arts and 

Sci. Trans., vol. 5, p. 572, pl. 58, fig. 41. 

1884. Leda acuta (Conrad). Verrill, Connecticut Acad. Arts 

and Sci. Trans., vol. 6, p. 259, pl. 30, fig. 15. 

1886. Leda acuta Conrad. Dall, Harvard Coil. Mus. Comp .. 

Zoology Bull., vol. 12, p. 251; pl. 7, figs. 3a, 3b, 8. 

1889. Leda acuta Conrad. Dall, Harvard Coli. Mus. Comp. 

Zoology Bull., vol. 18, p. 438. 

1889. Leda acuta Conrad. Dall, U. S. Nat. Mus. Bull. 37, 

p. 44, pl. 7, figs. 3a, 3b, 8; pl. 45, fig. 15; pl. 64, fig. 140. 

1898. Leda acuta Conrad. Dall, Wagner Free Inst. Sci. Trans.,. 

vol. 3,.pt. 4, pp. 592, 593. 

1904. Leda concentrica (Say). Glenn, Maryland Geol. Survey,. 

Miocene, p. 397, pl. 108, figs. 1, 2 (part). 

1906. Leda acuta (Conrad). Clark, Maryland Geol. Survey,. 

Pliocene and Pleistocene, p. 208, pl. 65, figs. 5-8. 

Conrad described this species in 1832, as follows: 

Shell ovate elongated, convex, with numerous regular concentric striae; anterior side slightly recurved and very acute at 

the ~xtremity, and with the dorsal margin sunk so as to form a 

lanceolate depression; beaks behind the center; fosset very 

small and hardly oblique. 

Habitat: Tertiary of Virginia. 

Type: Academy of Nat ural Sciences, Philadelphia. 

The perplexing possibilitie:-; of variation in Leda acuta 

Conrad are due largely to its wide geographic distribution and to its great geologic range. The recent 

representatives present a comparative uniformity of 

development, whereas the Tertiary forms indicate a 

period of instability and evolution for the species. 

In the young the valves are higher, decidedly less 

convex, and the posterior dorsal margin straighter. 

The great majority of the numerous Alum Bluff 

individuals commonly referred to Leda acuta have 

been distributed among Leda proteracuta and its 

subspecies, but there remain a few forms, most of 

them immature and badly worn, which probably 

represent a species distinct from both acuta and 

proteracuta but which have been tentatively included 

under the former. They are characterized by a 

relatively low, transversely ovate, trigonal outline 

and a concentric sculpture of very low, narrow, 

broadly rounded concentric ridges separated by little 

more than linear grooves, approximately uniform 

from the umbones to the ventral margin, slightly 

more compressed anteriorly, and not persistent across 

the rostrum. The normal sculpture of Leda acuta 

is a little more elevated and sharper, and there is no 
PRIONODESMACEA AND ANOMALODESMACEA 13 

subspecies of proteracuta which combines so fine and 

close a sculpture with one so much compressed. 

Occurrence: Chipola formation, localities 12213P, 

12564P, 13419P, 17151r. 

Outside occurrence: Miocene: Calvert formation, 

Virginia; St. Marys formation, Virginia, North Carolina; Yorktown formation, Virginia, North Carolina; 

and Duplin formation, North Carolina, Soutli Carolina, Georgia. Pliocene: Waccamaw formation, 

North Carolina, South Carolina; Caloosahatchie 

formation, Florida; and Croatan formation, Virginia, 

North Carolina. Pleistocene: Maryland, North 

Carolina, South Carolina, Florida. Recent: Rhode 

Island to Sombrero, in 7 to 225 fathon1s. 

Leda proteracuta Gardner, n. sp. 

Plate II, Figures 17-18 

1898. "Leda acuta Conrad." Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 592 (part). 

Not Nucula acuta Conrad, Alllerican marine conchology, 

p. 32, pl. 6, fig. 1, 1832. 

Shell rather small, delicate, polished, broadly and 

smoothly rounded in front of the umbones, narrow 

and cuneiform behind them. Umbones low, flattened upon their sun1mits, the apices obtuse, incurved, and feebly opisthogyrate, submedial or 

slightly anterior in position. Lunule narrow, lenticular, defined by the obtuse angulation of the shell 

and by the abrupt change in the character of the concentric sculpture. Escutcheon broad, produced to 

the posterior extremity of the shell, very finely and 

sharply striated. Rostrum acutely rounded even to 

the tip, thrown into relief by the obscure depression 

in front of it and in the majority of forms by the absence of the concentric sculpture which ornaments the 

greater part of the disk. Concentric sculpture developed to a greater or less degree over the disk; umbones finely and sharply ridged, the ridges broadening and becoming more obtuse away from the urnbones but persisting as a rule to the ventral margin, 

most elevated medially, usually obsolete upon the 

keel and more or less obsolete upon the depression 

in front of the keel and often upon the anterior portion of the disk as well; the ridges numbering normally 

from 15 to 20 if persistent to the base, separated on 

the tnedial portion of the shell by interspaces of about 

their own width but more crowded ventrally. Ligament internal, lodged in a minute chondrophore sunk 

deep beneath the umbones. Dentition normal for 

the group, the anterior series including approxirnately 

17 teeth, the posterior approximately 12; teeth delicate, coJnpressed, elevated in the medial portion of 

each series, especially of the posterior, fine and 

crowded near the chondrophore, slightly /\-;shaped, 

the angle directed toward the umbones. Muscle and 

mantle scars obscure because of the high polish of 

the interior. Anterior adductor m.oderately large, 

!ol6il\lii 0~50-:~ (14:.!-A) 

irregular in outline, placed just within the distal 

extremity of the hinge; posterior adductor much 

smaller, narrow, elongated in the direction of the 

dorsal margin. Pallial sinus short, broad, ascending, 

obtusely truncate at the extremity. Pallial line moderately distant fron1 the basal margin. 

Dimensions: Altitude, 2.8 millilneters; latitude, 5.0 

millimeters; semidiameter, 1.5 millimeters. 

Type: U.S. Nat. Mus. No. 352292. 

Type locality: No. 7257, Sexton's marl bed, Tenmile Creek, Calhoun County, Fla. 

Leda proteracu.ta is one of several species and subspecies included in the reference labels within the 

confines of that protean species Leda acuta Conrad. 

It is quite possibly the ancestor of Conrad's species 

and resembles its descendant in the range of variation. It is, however, constantly smaller than Leda 

acuta, n1ore delicate, and as a rule relatively higher. 

The few individuals in the Chipola which it has not 

seeined advisable to separate specifically from Leda 

acuta have a lower, n1ore compressed sculpture, uniformly close over the 1nedial portion of the disk though 

weakening laterally. 

Leda proteracuta, s. l. includes those forms that are 

characterized by a wide, finely striated escutcheon and 

a sculpture of more or less obtuse concentric ridges, 

rarely persistent across the rostrum, commonly ob::Solete toward both the anterior and the posterior lateral 

margins and in some specimens restricted to the tips 

of the umbones, the ridges usually of low or moderate 

elevation and fairly close and regular in spacing, some 

of them conspicuously coarse and distant toward the 

umbones and others narrow, subacute, and. quite 

closely spaced. The individuals in which the sculpture 

is conspicuously coarse, conspicuously fine, or conspicuously absent are excluded from Leda proterac·uta 

s. s. The coarsely sculptured individuals are segregated under the subspecies dystakta. As in the still 

rnore distantly sculptured Leda diphya, the sculpture 

of dystak.ta becon1es abruptly finer, closer, and commonly less regular upon the . ventral portion of the 

shell. Leda dodona Dall is closely related to these 

coarser peripheral members, but it is Inore compressed toward the umbones and the ornamentation 

upon the escutcheon is irregular and more or less 

obsolete. The individuals in which the sculpture is 

restricted to the 'tips of the umbones and to crowded 

incrementals toward the ventral margin of the adults 

are segregated under the subspecies leita. These 

forms are for the most part more delicate and highly 

polished than ·is normal for the species. Those 

individuals that are characterized by a relatively fine, 

close, subacute sculpture have been segregated under 

diamesa. Through diamesa the species Leda protera.cuta s. l. is related to the still more finely, sharply, 

and regularly sculptured Leda leptalea and through 

Leda leptalea in turn to Leda canonica meiopykna and 
14 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Leda canonica s. s., a shell so finely ornamented that 

under low magnification the ridges appear as a mere 

shagreen upon the surface. There is a less complete but roughly parallel Aeries in the Shoal River 

fauna. Leda polychoa is the analog of proterac1.lta but 

runs a little larger and relatively high~r and is more 

obliquely flattened upon the umbones than the 

Chipola species. The subspecies dejttniak v.aries 

along lines similar to thoae followed by le,ita, but the 

sculpture is never so nearly obsolete. Leda leiorhyncha has no exact analog in the Chipola, for the 

concentric ridges are not only less persistent than in 

polychoa but they are also decidedly finer, suggesting 

in this variation Leda proteracuta diamesa. 

Leda proteracu.ta is abundant not only in the wider 

but also in the restricted sense throughout the 

Chi pol a. 

Occurrence: Chipola for1nation, localities 10609P, 

7257P, 2213a, 2564a, 3419\ 7151P. 

Leda linifera chipolana Dall 

1898. Leda linijera var. chipolana Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 591. 

Dall describes this variety as follows: 

The Chipola beds have afforded another species of the same 

group (Nat. Mus. 114808) which in form and sculpture much 

resembles Leda linijera, but the shell is more inflated, the 

rostrum more pointed, with a marked inflection of the basal 

margin below it, and the anterior end is more attenuated. 

For the present this may take the provisional name of Leda 

linijera var. chipolana, though sufficient material would probably 

show it to be distinct. It is represented in the collection by 

only a single specimen 2.5 millimeters long. 

Type: U.S. Nat. Mus. No. 114808. 

The unique type is an extremely young form from 

which the entire outer surface has been removed by 

erosion. The few characters which were developed 

during the short life of the shell are so ill preserved 

that they do not furnish sufficient basis for identification with other individuals. The type, however, 

is apparently the young of Leda proteracttfa Gardner, 

n. sp. 

Occurrence: Chipola formation, locality 2213r. 

Leda proteracuta dystakta Gardner, n. subsp. 

Plate III, Figure 5 

Shell similar in general aspect to Leda proteracuta, 

s. s., rather small and thin, moderately inflated. 

Anterior portion of shell broadly rounded or obscurely 

truncate at the lateral extremity, the posterior portion cuneate, sharply rounded at the tip of the rostruin. Umbones low, broad, obtuse at the tips, 

incurved,. opisthogyrate, slightly anterior. Lunule 

very narrow, lenticular, slightly depressed, defined 

by the abrupt disappearance of the concentric sculpture. Escutcheon very wide, biconcave in the double 

valves, the space between the rostrum and the. dorsal 

margin moderately excavated, persistent to the tip 

of the rostrum, finely and closely striated independently of the sculpture upon the disk. Rostrum quite 

sharply angulated toward the beaks, rounded off 

toward the outer extremity, emphasized by the feeble 

depression and weakened or obsolete sculpture in 

front of it. Anterior ray usually distinct. Sculpture 

very coarse for the group, e3pecially in the umbonal 

region: Concentric ridges at the extreme tips of the 

umbones fine, sharp, and closely spaced, the eight or 

nine succeeding ridges broad for the group, obtuse, 

quite prominently elevated, somewhat flexuous and 

inclined to arch upward toward the umbones, more 

or less corr:pressed anteriorly, pinching out and disappearing toward the rostrmn, separated by interspaces almost double their own width; ventral portion 

of shell much more finely and less regularly sculptured, a few of the ridges persistent across the rostrum. Ligament minute, trigonal, sunk deep beneath 

the umbones. Teeth laminar, acutely angulated, 

somewhat j\-shaped, the angle dorsally directed, 

quite sharply elevated in the medial portion of each 

series, densely crowded toward the umbones, especially in the anterior series; anterior series consequently including 18 denticles, the posterior only 14. 

Adductor scars obscure, especially the rather large, 

roundish anterior scar; posterior impression much 

smaller, elongated parallel to the dorsal margin, 

slightly depressed. Pallial sinus short, broad. ascending, obliquely truncate at its extremity. 

Dimensions: Altitude, 3.5 millimeters; latitude, 6.4 

millimeters; semidiameter, 1. 7 millimeters. 

Type: U.S. Nat. Mus. No. 352294. 

Type locality: No. 2213, 1· mile below Baileys 

Ferry, Chipola River, Calhoun County, Fla. 

Leda proteracuta dystakta differs from protera.cuta 

s. s. in the coarser, more flexuous, and more distant 

concentric sculpture of the dorsal portion of the 

shell. The majority of the individuals preserved 

are juveniles which are sculptured with approximate 

regularity on the dorsal and ventral portions of the 

shell. The adults, however, exhibit a change in 

sculpture which both in degree and kind suggests L. 

diphya, though the umbonal sculpture is not so coarse 

in the species from Chipola River as in that from 

Choctawhatchee River, and the age variation is consequently less marked. 

Occurrence: Chipola formation, localities 10609P, 

7893r, 7257r, 2213P, 2564P, 3419P, 

Leda proteracuta leita Gardner, n. subsp. 

Plate III, Figures 1-4 

Shell rather small and delicate, moderately inflated, 

very highly polished, transversely ovate-trigonal in 

outline. Anterior portion of shell broadly and 

smoothly rounded, the gently inclined or feebly 

convex dorsal margin merging smoothly into the 

rounded, lateral margin and this in turn into the up-
PRIONODESMACEA AND ANOMALODESMACEA 15 

curved base line. Posterior portion of shell narrow, 

produced, and rostrate, the dor~al n1argin very slightly 

excavated, rounding sharply at the tip of the_ beak 

into the uocurved base. Ventral1nargin asyn11netrically arcu~te, the maxin1um curvature in line with 

the umbones. Umbones low, broadly rounded, the 

apices incurved and feebly opisthogyrate. Lunule 

narrow, lenticular, defined by the obscure angulation 

of the valves and by the abrupt change in the character of the concentric sculpture if present. Escutcheon 

much wider, produced to the posterior extremity of 

the shell, very finely and sharply striated. Rostrum 

narrow and compressed in the umbonal region, a. 

little broader and less acute toward the extremity, 

emphasized slightly by the obscure depression in 

front of it. Anterior ray quite distinct on the polished surface. External surface lustrous, sculptured 

only by a feeble corrugation in the umbonal region; 

the ridges fine and sharp at the apices but broadening 

as they disappear, more persistent, as a rule, on the 

medial portion of the disk than toward the margin, 

microscopically fine and crowded, concentric; scratches 

also ·commonly visible on the surface glaze, e3pecially 

toward the ventral margin, which is in places roughened by resting stages, with equally fine, fortuitous 

radials locally developed on the anterior and medial 

portions of the shell. Ligament internal, lodged 

in an exceedingly small chondrophore sunk deep 

beneath the umbones. Teeth rather delicate, but 

acute and prominently elevated in the medial portion 

of each series; anterior series including approxilnately 

18 teeth, the posterior 11 or 12-the larger. number 

in the anterior series due to the larger number of 

fine crowded subumbonal teeth. Inner surface ' ' highly polished, obscuring the adductor and mantle 

scars. Anterior adductor scar moderately large, 

roundish, placed directly within the distal extremity 

of the hinge. Posterior adductor scar much smaller, 

extremely narrow, elongated parallel to the dorsal 

margin. Pallial sinus short, broad, angular, the 

margins rudely parallel, the extremity obliquely 

truncate. Pallial line at some little distance from 

the basal margin. 

Dimensions: Altitude of right 'Valve, 3.0 millimeters; 

left valve, 3.0 millimeters. Latitude of right valve, 

6.0 millimeters; left valve, 5.5 millimeters. Semidiameter of right valve, 1.5 millimeters; left valve, 

1.45 millimeters. 

Cotypes: U.S. Nat. Mus. No. 352293. 

Type loc~lity: No. 7257, Sexton's marl bed, Tenmile 

Creek, Calhoun County, Fla. 

Leda proteracuta leita is a small, delicate shell readily 

isolated from the other Alum Bluff Ledas by the 

smooth and highly lustrous surface. It is separated 

from Leda proteracuta s. s. by the restriction of . the 

sculpture to the apical region and the growth hnes 

toward the ventral margin. 

Occurrence: Chipola formation, localities 10609P, 

7257P, 2213a, 2564a, 3419a, 9994P, 7151°. Oak Grove 

sand, locality ? 264W. 

Leda proteracuta diamesa Gardner, n. subsp. 

Plate III, Figure 6 

Shell similar in dimensions and outline to others of 

the group, rather small, moderately inflated, tran.sversely ovate-trigonal in outline, broadly rounded 1n 

front of the umbones, produced and rostrate behind 

them. Umbones low, rounded, feebly opisthogyrate, 

subcentral or slightly anterior. Lunule narrow, lenticular, feebly depressed, indicated chiefly by the 

abrupt weakening of the concentric sculpture. Escutcheon much wider, produced to the posterior extremity, concave between the rostrum and the dorsal 

margin, yery finely and regularly striated; rostrum 

quite sharply angulated near the umbones, more 

obtuse away from the umbones, emphasized by the 

obscure depression in front of it. Anterior ray feeble 

or obsolete. External surface corrugated with narrow, acutely rounded concentric ridges, most elevated 

medially, somewhat flattened, as a rule, anteriorly 

and weakening toward the rostrum though usually 

persistent across it, numbering not. far fro~ ?O, 

regularly spaced toward the umbones 1n the ~aJOrity 

of forms but tending to become crowded and Irregular 

near the basal margin. Ligament pit minute, trigonal, sunk deep beneath the umbones. Dentition 

vigorous, normal for the group. Teeth elevated ~nd 

acutely pointed in the medial portion of each senes, 

very fine and crowded toward the umbones, especially 

in the anterior series; the number of teeth consequently as many as 18 or 20 in the ~nterior seri~s, 

though only about 14 in the posterwr. A~terwr 

muscle scar irregular and somewhat roundish 1n 

outline, the posterior a mere dent. Pallial sinus 

short,broad, ascending obliquely, truncated dorsally. 

Pallial line not very far from the basal margin. 

Dimensions: Altitude, 3. 7 millimeters; latitude, 6.5 

millimeters; semidiameter, 1.8 millimeters. 

Type: U.S. Nat. Mus. No. 352295. 

Type locality: No. 7257, Sexton's marl bed, Tenmile Creek, Calhoun County, Fla. 

Leda proterac1L.ta diamesa includes those forms at 

the opposite end of the series from the coarsely sculptured forms that have been segregated under Leda 

proteracuta dystakta. Leda proteracu.ta diamesa is 

more closely sculptured than Leda proterac·u.ta s. s., 

the spacing of the concentric ridges is usually less 

re{7'ular and the tendency of the sculpture to become 

obsolet~ toward the rostrum and the anterior extremity is much less marked. 

Many of the individuals approach very closely to 

Leda leptalea, though the concentric ridges arc coarser, 

more obtuse, and usually more irregular and less 

persistent toward the rostrum. . . . P 

Occurrence: Chipola formatwn, locahtws 7257 ) 

2213°, 2564°, 3419°, 7151P. 
16 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Leda leptalea Gardner, n. sp. 

Plate III, Figures 7-8 

Shell rather sn1all for the genus and delicate, moderately inflated, transversely ovate-trigonal in outline. Anterior dorsal margin gently declining, the 

posterior more steeply and slightly upturned at the 

extremity. Anterior lateral margin broadly rounded 

or obscurely truncate, the posterior extremity of the 

rostrum very sharply rounded. Base line strongly 

but somewhat asymmetrically rounded. Umbones 

rather low and broad, obtuse and feebly opisthogyrate at the tips, slightly anterior in position, Lunule 

very narrow, lenticular, feebly depressed, defined 

chiefly by the abrupt weakening of the concentric 

striae. Escutcheon much wider, persistent almost to 

the posterior extremity, concave between the rostrum and the dorsal margin, very finely and regularly 

striated in harmony with the concentric sculpture 

upon the disk. Rostrum acutely angulated toward 

the umbones, sharply rounded away from them. 

External surface corrugated with 30 to 40 fine, closely 

and regularly spaced, subacute, concentric ridges, 

approximately uniform in prominence from the lunule 

to the escutcbeon, though flattened somewhat upon 

the anterior portion of the shell, continuous for the 

most part across the rostrum, though weakening upon 

it toward the ventral margin. Ligament pit minute, 

trigonal, entirely internal, sunk deep beneath the 

umbones. Dentition normal for the group. Denticles acute, prominently elevated in the medial portion 

of each series, slightly A-shaped, the apex of the angle 

directed toward the umbones, nun1bering approximately 16 in the anterior series and 13 in the posterior, 

the larger number in the anterior series due to 

the more numerous minute teeth crowded in front of 

the umbones. Anterior muscle scar rather large, 

irregular in outline, placed just within the distal 

extremity of the hinge teeth. Posterior adductor 

sear mueh smaller, slightly sunken, elongated para1lel 

to the dorsal margin. Pallial sinus very short. 

rather broad, ascending. Pallial line at a moderate 

distance from the basal margin. 

Dimensions: Altitude, 3.5 millimeters; latitude, 5.7 

millimeters; semidiameter, 1.6 millimeters. 

Type: U.S. Nat. Mus. No. 352296. 

Type locality: No. 3419, McClelland farm, 1 mile 

below Baileys Ferry, Calhoun County, Fla. 

Leda leptalea is a species intermediate between the 

dissimilar forms Leda,proterac1.tta Gardner, n. sp., and 

Leda canonica Dall. It is more finely, sharply, and 

regularly sculptured than Leda proterac11ta but more 

coarsely and distantly than Leda canonica. The gaps 

between are partly filled on the one side by Leda 

proteracuta diamesa, a form characterized by a sculpture not only coarser than that of Leda leptalea but 

usually less regular and less persistent toward the 

rostrum; on the other side by Leda canonica meiopykna, 

a subspecies differing front Leda canonica only in the 

less fine concentric sculpture. Leda leptalea is well 

distributed through the Ch\pola, but it is not a common species at any of the known localities. 

Occurrence: Chipola formation, localities 10609P, 

2213P, 2564P, 3419P, 7151 r. 

Leda canonica Dall 

Plate III, Figures 15-17 

1898. Leda (linifera Conrad, var. ?) canonica Da.ll, Wagner 

Free Inst. Sci. Trans., vol. 3, pt. 4, p. 591. 

Dall describes this species as follows: 

The present form, represented by two small specimens about 

2.5 millimeters long, is more elongate, less compressed, the 

rostrum has a rounded dorsal keel, and the surface is uniformly 

covered with fine, even, concentric sculpture. It is probably a. 

distinct species, less robust than young Leda acuta Conrad of 

the same size but for which the material is hardly adequate 

to a. full description and figure. The shell is near Leda calatabianensis Seguenza,11 from the Astian of Italy. 

Shell rather small and delicate for the genus, 

moderately inflated, transversely ovate-trigonal in 

outline, quite strongly and nearly symmetri_cally 

rounded in front of the umbones, produced into a subacute rostrum behind them. Umbones well rounded, 

not very prominent, feebly opisthogyrate, slightly 

anterior in position. Lunule very narrow, lenticular, 

defined only by the abrupt weakening of the concentric 

sculpture. Escutcheon much wider, depressed, persistent to the tip of the rostrum, very finely and evenly 

threaded in harmony with the sculpture upon the disk. 

Rostrum subacute, sharply rounded at the tip, 

emphasized by the obscure depression behind it. 

Anterior ray obscure or obsolete. Concentric sculpture exceedingly fine and regular over the entire shell, 

continuous across the rostrum, the ridges numbering 

from 10 to 25 to the millimeter. Ligament pit 

minute, sunk deep beneath the umbones. Dentition 

vigorous, the teeth acute and prominently elevated in 

the medial portion of each series, slightly A-shaped, the 

angle directed toward the umbones. Anterior series 

including approximately 15 to 18 teeth; the posterior 

teeth less fine, crowded toward the umbones, and 

only about 12 to 15. Anterior muscle scar moderately 

large, irregular in outline, placed just within the distal 

extremity of the hinge. Posterior scar smaller, somewhat depressed, elongated parallel to the dorsal 

margin. Pallial sinus short, broad, ascending, obtusely 

rounded at its extremity. Pallial line at some little 

distance from the basal margin. 

Dimensions of right valve of an adul~ specimen: 

Altitude, 3.1 millimeters; latitude, 5.2 millimeters; 

semidiameter, 1.5 millimeters. Dimensions of left 

valve of another specimen: Altitude, 2.9 millimeters; 

latitude, 5.0 millimeters; semidiameter, 1.5 millimeters. 

u Seguenza, Giuseppe, Nuculidi terziarie rinvenute nelle provincie meridionali 

d'Italia: R. Accad. Lincei Mem., vol. 1, pl. 2, fig. 9a, 1877. 
PRIONODESMACEA AND ANOMALODESMACEA 17 

Type: U.S. Nat. Mus. No. 114806; figured specimen, No. 352300. 

Type locality: No. 2213, 1lnile below Baileys Ferry, 

Chipola River, Calhoun County, Fla. 

Unfortunately this not uncommon species was first 

described from juveniles of which one must serve as the 

type. Leda canonica, includes the extreme end members in the Chipola of the Leda proteracuta group. 

The species is much more finely and more closely 

sculptured than any other of the Chipola species, 

though it approaches them through the subspecies 

meiopykna and Leda leptalea. The sculpture in Leda 

canonica (in a strict sense) is microscopically fine, and 

even under moderate magnification commonly appears 

as a shagreening rather than a true sculpture. 

Occurrence: Chipola formation, localities 7257P, 

2213P, 2564°, 3419°, 7151P. 

Leda canonica meiopykna Gardner, n. subsp. 

Plate III, Figure 18 

Shell, small, rather thin, delicate, moderately 

inflated, transversely ovate-trigonal in outline, quite 

strongly rounded in front of the umbones, produced 

andobtuselyrostrate behind them. Umbones rounded, 

obtuse, subcentral, feebly opisthogyrate. Lunule extremely narrow, lenticular, ill-defined. Escutcheon 

quite wide, pernistent aln1ost to the extremity of the 

rostrum, concave between the rostrum and the dorsal 

margin, very finely and evenly striated with a concentric sculpture closer than that upon the disk. 

Rostrum acutely angulated toward the umbones, 

sharply rounded toward the posterior extremity; surface covered with 40 to 50 fine, regular, subacute 

concentric ridges, approximately uniform in prominence throughout their extent though slightly lower 

and more obtuse on the anterior portion of the shell, 

persistent across the rostrum except toward the ventral 

margin. Ligament minute, sunk deep beneath the 

umbones, entirely interned. Dentition normal for 

the species; teeth lanlinar, elevated, acute, somewhat 

A-shaped, the angle directed toward the umbones, 

10 or 11 in the posterior series, 12 or 13 in the anterior. 

Anterior adductor scar moderately large, irregular in 

outline, placed at the distal extre:rn.ity of the hinge. 

Posterior scar much smaller, elongated parallel to the 

dorgal margin. Pallial sinus short, broad, ascending. 

Pallial line rather distant from the basal margin 

Dimensions of right valve: Altitude, 3.0 millimeters; 

latitude, 5.6 millimeters; semidiameter, 1.2 millimeters. 

Type: U.S. Nat. Mus. No. 352301. 

Type locality: No. 2564, McClelland farm, 1 mile 

belo}V Baileys Ferry, Calhoun County, Fla. 

Leda canonica meiopykna differs from Leda canonica 

s. s. only in the less crowded concentric sculpture. 

This character is so marked, however, that there seems 

to be reason for segregating the individuals that exhibit 

. it. Through the subspecies Leda canonica approaches 

Leda leptalea, although there is a distinct hiatus between the exceedingly fine sculpture of canonica and 

the less fine ornamentation of leptalea. The subspecies 

is rather less common than the restricted canonica. 

Occurrence: Chipola formation, localities 2213P, 

2564P, 3419P. 

Leda polychoa Gardner, n. sp. 

Plate III, Figures 9-10 

Shell of moderate dimensions for the genus, quite 

solid, rather compressed in the immature forms, 

usually inflated in the adult, ovate-trigonal in outline, 

produced and acutely rostrate behind. Umbones 

submedial or anterior, very small but rather prominent 

because of their position at the apex of the triangle, 

flattened upon their summits, the tips incurved and 

feebly opisthogyrate. Lunule very narrow, lenticular, 

the margin sharply elevated toward the umbones, 

evanescing away from the umbones so that the lunule 

is indicated merely by the flattening of the shell and 

by the abrupt weakening of the concentric sculpture. 

Escutcheon also lenticular but much broader and 

more produced than the lunule; margins elevated 

along the entire length of the escutcheon, though 

more sharply pinched toward the :umbones; concentric 

sculpture upon the escutcheon much sharper than 

upon the lunule. Shell in front of the umbones 

smoothly rounded, behind the umbones acutely 

angulated. Anterior dorsal margin oblique or feebly 

arched, merging smoothly into the rounded lateral 

margin and the lateral margin into the upcurved 

base line; posterior dorsal margin obliquely produced, 

little or not at all excavated except at the slightly 

upturned extremity, where it intersects the base 

line. Base asymmetrically arcuate, the maximum 

curvature in line with the umbones. Rostral angle 

acute and persistent to the posterior extremity. 

Anterior ray obscure or obsolete. Sculpture concentric, exceedingly variable, very fine, sharp, and 

regular in the umbonal region, less fine, more or less 

obtuse, and commonly irregular away from the umbones; the number of concentric ridges usually from 

30 to 35 but in a few specimens as high as 45; the 

ridges flattening slightly toward the rostrum but not 

obsolete upon it, every other one, as a rule, persisting 

across the escutcheon. Ligament internal, lodged in a 

minute triangular pit directly beneath the umbones. 

Dentition vigorous, the anterior series feebly convex 

and including approximately 16 teeth, the posterior 

feebly concave and including approximately 15' teeth; 

teeth very fine and crowded beneath the umbones but 

prominently elevated in the medial portion of the series, 

acutely tapering but not hooked at their summits, compressed at the base and slightly A-shaped, the angle 

directed toward the umbones; distal teeth moderately 

prominent. Adductor scars small and obscure on the 

highly polished surface, the anterior irregular in 
18 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

outline, placed at the distal extremity of the hinge, 

accentuated in the heavier shells by a slightly raised 

margin, the posterior much smaller than the anterior 

and quite deeply indented. Pallial sinus very short, 

linguiform, usually ascending slightly. Pallial line 

moderately distant from the base. 

Dimensions: Altitude, 3.5 millimeters; latitude, 6.1 

millimeters; diameter, 2.5 millimeters. 

Type: U.S. Nat. Mus. 352297. 

Type locality: No. 3742, Shell Bluff, Shoal River, 

Walton County, Fla. 

Leda polychoa is the Shoal River representative of 

the Leda proteracuta group in the Chipola. Both 

species are exceedingly variable, and the end members 

very closely approximate one another. However, 

the ensemble in the two forms is distinct and constant through the horizon which each characterizes. 

Leda polychoa Gardner, n. sp., runs a trifle larger and 

heavier than Leda proteracuta and is typically more 

oblique posteriorly. The concentric ridges are as a 

rule narrower ·and less regularly spaced in the individual, though exhibiting a much lower range of specific variation than Leda prote'f·acuta. The young are 

much compressed in both species, but the adults in 

Leda polychoa are more inclined to be inflated than in 

Leda proteracuta. In some individuals in the Shoal 

River species the flattening of the umbones is so pronounced and the inflation of the medial portion of the 

disk so high that· the shell has a pathologic aspect. 

This is especially true of the short, high forms with 

submedial umbones. The concentric ridges as a rule 

are fine, sharp, and regular in the umbonal region, less 

fine and commonly less regular on the medial portion 

of the disk, and more crowded again toward the ventral margin, so that the change in sculpture with age 

combined with the change in outline gives a very 

marked age variation to the species. Those forms 

that are characterized by a more or less obtuse and 

irregular concentric sculpture, feeble or obsolete 

upon the rostrum, have been segregated under the 

subspecies defuniak, so named because of the prevalence of this type of sculpture in the environs of 

De Funiak Springs. The subspecies also occurs, however, together with Leda polychoa s. s. at the type 

locality at Shell Bluff. 

Occurrence: Shoal River formation, localities 3856°, 

2645r, 3732r, 3742a, 10658P, 5195P, ?507W, 3748P, 

9960P, 9957c, 10603°, 10608°. 

Leda polychoa defuniak Gardner, n. subsp. 

Plate III, Figures 11-12 

Shell rather small, solid, trigonal, smoothly rounded 

in front of the umbones, rostrate and sharply cuneate 

behind them. Umbones small, not very prominent 

except for their position, incurved and feebly opisthogyrate, submedial or slightly anterior. Lunule 

very narrow and ill-defined. Escutcheon quite wide, 

produced to the posterior extremity, biconcave in the 

double valves, the outer margins sharply elevated, 

the hinge margin also slightly raised. Concentric 

sculpture quite sharp and regular upon the escutcheon 

but more or less obsolete upon the lunule. Anterior 

dorsal margin not far from horizontal, merging 

smoothly into the broadly rounded lateral margin. 

Posterior dorsal margin oblique except at the slightly 

upturned extremity, produced until it intersects the 

upcurved base line. Basal margin asJmmetrically 

arcuate, the maximum curvature directly beneath 

the umbones. Sculpture exhibiting a range of variation parallel to that of Leda polychoa s. s. but 

usually less sharp and regular and obsolete upon the 

rostrum; concentric ridges normally fine, sharp, and 

regular upon the umbones, becoming more obtuse, 

less regular, and nwre distant away from the umbones, 

feeble, or obsolete toward the rostrum, and less 

elevated and in some specimens obsolete toward the 

anterior extremity; ventral portion of shell more 

finely and sharply sculptured as a rule than the medial, 

the ridges persistent in some of the senile forms 

across the rostrum; concentric ridges normally between 35 and 40 as in Leda polychoa s. s. Ligament 

internal, lodge~ in a minute, trigonal chondrophore 

directly beneath the umbones. Dentition vigorous; 

anterior series feebly arcuate and including 18 to 20 

teeth, the posterior feebly concave and including 

approximately 15 teeth; the teeth laminar, fine and 

crowded toward the umbones, prominently elevated 

in the medial portion of each series, acutely tapering, 

slightly A-shaped. Interior ·highly polished. Muscle 

scars and pallial line obscure. Anterior adductor scar 

irregular, rounded in outline, of moderate size and 

placed directly beneath the distal extremity of the 

hinge. Posterior scar much smaller, depressed dorsally, elongated parallel to the dorsal margin. Pallial 

line rather distant from the base. Pallial sinus short, 

linguiform, ascending. 

Dimensions: Altitude, 4.0 millimeters; latitude, 

7.5 millimeters; semidiameter, 2.0 millimeters. 

Type: U.S. Nat. Mus. No. 352298. 

Type locality: No. 5618, 3~ miles southwest of De 

Funiak Springs, Walton County, Fla. 

The subspecies characterized by the feeble or 

obsolete sculpture upon the rostrum and usually by 

a less sharp and regular sculpture upon the disk is the 

common Leda in the environs of De Funiak Springs. 

The sculpture as a rule is sharper and more regular at 

the type locality of the subspecies than it is in the 

individuals that occur along Shoal River at the type 

locahty of Leda polychoa in a strict sense. The r~nge 

of variation in outline is lower than in the restricted 

species, and the short, highly inflated type is absent. 

The characters of the subspecies are commonly more 

marked in the young than in the adult, for in some of 

the adults the sculpture toward the ventral margin 
PRIONODESMACEA AND ANOMALODESMACEA 19 

persists across the rostrum. In a few forms the 

sculpture is obsolete over so wide an area both on 

tl1e posterior and the anterior portion of the shell 

that the ornamentation sugge~ts Leda proteracuta 

le'l:ta. A series of parallel variations is exhibited not 

only in the subspecies of Leda proteracuta from the 

Chipola but also in Leda acuta, which occurs in the 

D~plin Miocene of North Carolina. 

Occurrence: Oak Grove sand, locality ~9961P. Shoal 

River formation, localities 3742P, 5079r, 3733r, 3748r, 

3747P, 7261 r, 7264P, 996(:}P, 9957c, 10603°, 10608°1 5618°. 

Leda leiorhyncha Gardner, n. sp. 

Plate III, Figures 13-14 

Shell rather small, solid, moderately inflated, transversely ovate-trigonal in outline, broadly and symmetrically rounded in front of the umbones, cuneate 

behind them, the obliquely produced posterior dorsal 

margin intersecting the upcurved base in a subacute 

angle. Umbones low, rounded upon their summits, 

incurved, opisthogyrate, slightly anterior. Lunule narrow, ill-defined, obscurely laminated. Escutcheon 

much wider, produced to the posterior extremity of 

the shell, well defined, quite sharply laminated in 

harmony with the sculpture upon the disk. Rostral 

angle acute toward the umbones, obtuse toward the 

outer margin. External surface sculptured with very 

fine, usually regular, quite sharply elevated or obtusely 

flattened concentric ridges, numbering about 40 to 

45. Rostrum smooth, the unsculptured area becoming increasingly narrow toward the umbones. Sculpture less elevated upon the anterior portion of the 

shell than upon the medial but persistent to the lunule. 

Ligament internal, lodged in a minute, subumbonal 

chondrophore. Dentition vigorous; teeth compressed, 

somewhat A-shaped, the angle directed toward the 

umbones, arranged in two discrete series; anterior 

series feebly arched and including as a rule from 16 

to 18 teeth; posterior series oblique or very slightly 

concave and including from 13 to 15 denticles; medial 

teeth in each series conspicuously elevated, less prominent toward the ventral extremities of the hinge and 

exceedingly small and crowded near the chondrophore. 

Anterior adductor scar obscure, irregular in outline, 

placed directly within the distal extremity of the 

hinge. Posterior scar smaller but much more distinct, 

elongated parallel to the hinge, impressed dorsally. 

Pallial sinus broad but rather short. Pallial line at 

some little distance from the basal margin. 

Dimensions: Altitude, 3.5 millimeters; latitude, 6.0 

millimeters; semidiameter, 1.6 millimeters. 

Type: U.S. Nat. Mus. No. 352299. 

Type locality: No. 3742, Shell Bluff, Shoal River, 

Walton County, Fla. 

Leda leiorhyncha is a member of the group of Leda 

polychoa and closely resembles the more elongated, 

finely sculptured individuals of that species. Unlike 

them, however, the rostrum is smooth, as if it had 

been planed and later polished. The absence of sculpture upon the rostrum suggests Leda polychoa defu.nialc, but the sculpture of the subspecies is more 

crowded and more regular and usually sharper. Leda 

leiorhyncha exhibits less variation than any other of the 

Shoal River Ledas, possibly because it is more restricted in its distribution. 

Occurrence: Shoal River formation, localities 3742°, 

~ 7264r. 

Leda diphya Gardner, n. sp. 

Plate IV, Figures 13-15 

Shell of moderate dimensions~ quite heavy, highly 

inflated in the adult, ovate-trigonal, the anterior portion of the shell broadly and symmetrically rounded, 

the posterior portion narrow, rostrate, and cuneiform. 

Umbones gibbous except at the. apices, which are flattened, incurved, opisthogyrate, and slightly anterior. 

Anterior dorsal margin merging smoothly into the 

broadly rounded lateral margin, which in turn merges 

into the upcurved base line. Posterior dorsal margin 

feebly convex, produced to meet the ventral margin. 

Base line asymmetrically arcuate, the maximum curvature in line with the umbones. Lunule extremely narrow, lenticular, defined by the abrupt weakening of 

the concentric laminae. Escutcheon conspicuously 

broad, concave, sharply differentiated, finely and regularly striated without regard to the sculpture upon the 

disk. Rostral angle acute toward the umbones, less 

sharp away from them but persistent to the outer extremity. Ornamentation remarkably discrepant in 

the young and the adult; juveniles and the umbonal 

region in the adults sculptured with 8 or 9 obtuse 

ridges, elevated, somewhat flexuous, and inclined to 

arch slightly upward toward the umbones, flattening 

near the margin of the lunule and obsolete upon 

the rostrum, separated from one another by wider 

interspaces, microscopically striated oblique to the 

ridges; change in character of sculpture very abrupt, 

the ventral two-thirds or more of the shell being 

finely and closely ribbed with about 25 narrow, 

rounded threads approximately uniform from the 

lunule to the rostrum which they override; interspaces little more than linear, not quite so narrow 

upon the medial portion of the disk where the shell 

is most inflated. Ligament internal, lodged in a 

minute pit sunk deep beneath the umbones. Teeth 

arranged in two discrete series approximately 18 in 

the posterior, 20 in the anterior, the anterior series 

very slightly concave, the posterior very slightly 

convex; teeth much compressed, acute, somewhat 

A-shaped, the angle directed toward the umbones, 

prominently elevated in the medial portion of each 

series, rather densely crowded. Anterior adductor 

scar quite large, obscurely quadrate, placed at the distal extremity of the hinge. Posterior adductor scar 
20 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

little more than a deep dent oblique to the dorsal 

margin. Pallial sinus short, obtusely angula ted, ascending. Pallial line at some little distance from the 

basal margin. 

Dimensions: Altitude, 4.7 millimeters; latitude, 8.1 

millimeters; semidiameter, 2.1 millimeters. 

Type: U. S. Nat. Mus. No. 352302. 

Type locality: No. 7893, Boynton Landing, Choctawhatchee River, Washington County, Fla. 

There is no other post-Eocene Leda described from 

the east coast which exhibits an age variation so 

remarkable as that of Leda diphya, though it is suggested both in degree and kind by the Chipola River 

analog Leda proteracuta dystakta. Th~ young suggest Leda dodona and an unnamed species from the 

Shoal River, though they are more heavily sculptured 

than either of the forms in question. The adult 

sculpture, on the otheJ.; hand, suggests Leda proteracuta 

diamesa from the Chipola in its fineness, closeness, and 

regularity. This inconstancy of sculpture is a character exhibited by many of the Eocene species, and its 

persistence in the later fauna is noteworthy. Forms 

such as this should emphasize the inadvisability of 

describing juveniles. 

Occurrence: Chipola formation, locality 7893P. 

Leda dodona Dall 

Plate IV, Figure 6 

1898. Leda dodona Dall, Wagner Free Inst. Sci. Trans., vol. 3, 

pt. 4, p. 589, pl. 32, fig. 6. 

Dall describes this species as follows: 

Shell small, solid, slightly inequilateral, polished, strongly 

concentrically sculptured; sculpture of elegant, even, high, 

blunt-edged, slightly recurved lamellae, with deeply excavated, 

wider interspaces, which are striated by the lines of growth; 

the sculpture ends anteriorly at the margin of the lunule, and 

behind ceases on the rostral carina, about equally strong 

throughout; a radial depression extends from the beak to the 

anterior ventral margin, which it slightly emarginates; lunule 

narrow, transversely ribbed; escutcheon wider, extending to the 

end of the rostrum, bounded by a strong, rounded carina, on 

which the lamellre are conspicuous; within the carina the area is 

excavated and nearly smooth, except in the central part, where 

it is radially grooved; rostrum acute, slightly recurved near the 

tip, pallial sinus small; hinge with 19 anterior and 14 posterior 

rather solid teeth; chondrophore small, triangular. Longitude 

9, altitude 5, diameter 4 millimeters. 

Type: U.S. Nat. Mus. No. 135823. 

Type locality: Oak Grove, Yell ow River, Okaloosa 

County, Fla. 

A single valve was found near De Funiak Springs 

which, though too imperfect to name, is interesting 

because it indicates the existence of the dodona group 

in the Shoal River. This valve is apparently adult but 

smaller than Leda dodona and not quite so high. The 

umbones are very much flattened and finely and 

sharply sculptured at the tips. Away from the tips 

there are four or five heavy, rounded ribs which 

increase rapidly in prominence. Between the most 

conspicuous of these and the basal margin there are 

five additional ridges as broad but not so elevated as 

the medial rib, which by its prominence obscurely 

angulates the disk both externally and internally. 

The irregularity of the sculpture gives to the valve 

a pathologic aspect which may be normal for the 

species or may be merely an individual character. 

Occurrence: Oak Grove sand, localities 2646P, 5632r, 

9961r. 

Genus YOLDIA )\toller. 

1842. Yoldia Moller, Index molluscorum Groenlandiae, p. 18. 

Type: Yoldia arctica Moller. (Recent in theArctic 

Ocean.) · · 

The genus differs frmn Leda mainly in the posterior 

gape of the valves, the longer siphons and the consequently deeper pallial sinus. _ 

Only two species have been recognized in the Alum 

Bluff. One of them, Yoldiafrater Dall, is abundant in 

the Oak Grove and is present in the Shoal River and 

with modifications of doubtful taxonomic value in the 

Chipola; the other, Yold1:U soror, is closely related to it 

and is restricted to the Shoal River. Both species are 

members of the very compact and closely related 

group represented in the east coast Miocene by 

Y oldia laevis Say and in the Pleistocene and Recent by 

Yoldia'limatula Say. It is rather surprising to find 

this typically boreal genus so prominent in the warmwater faunas of the Alum Bluff. 

Adult shell decidedly more than twice as long as it is broad. 

· Y oldia frater Dall. 

Adult shell approximately twice as long as it is broad. 

Yoldia soror Gardner, n. sp. 

Yoldia frater Dall 

Plate IV, Figure 7 

1898. Yoldia frater Dall, Wagner Free Inst. Sci. Trans., vol. 3, 

pt. 4, p. 596, pl. 32, fig. 1. 

Dall describes this species as follows: 

She11 polished, thin, elongate, much resembling Y oldia laevis, 

from which it is distinguished by the less arcuate base, more 

attenuated anterior end, somewhat more compressed form, 

and, in the great majority of specimens, by having on the convexity of the beaks and the early part of their posterior slope a 

concentric sculpture of fine even riblets with about equal interspaces. There is also on the escutcheon an elevated radial 

line, absent on the corresponding part of Y oldia laevis, which 

also attains a nearly one-third larger size when full grown. 

There are about 26 teeth on each side of a small subumbonal 

chondrophore. Longitude 19, altitude 8, diameter 4 millimeters. • 

This shell is perhaps the ancestor of Y oldia laez>is, from which 

it can usually be readily distinguished by its more rectangular 

form and sculptured umbones. 

Type: U.S. Nat. Mus. No. 135821. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

There are, as a rule, only 21 to 23 teeth in each of the 

dental series. The pallial sinus is broad, linguiform, 
PRIONODESMACEA AND ANOMALODESMACEA 21 

with rudely parallel margins and a broadly rounded 

extremity. The pallial line runs very close to the 

basal margin. 

The Chipola forms are generally thinner shelled and 

more compressed than those from Oak Grove, and the 

sculpture upon the umbones is more feeble and. less 

persistent. However, these characters are so inconstant in both the Chipola and the Oak Grove individuals that they are of very doubtful taxonomic value. 

The species is very prolific at the type locality and is 

abundant and widespread throughout the horizon. 

It is not an uncommon form in the Chipola fauna 

but nothing like so abundant as it is in the Oak Grove. 

Occurrence: Chipola formation, localities 10611 a, 

10596°7 10609°7 10610P, 7893P, 7257P, 2213°7 2564P, 

3419P, 7151 P. Oak Grove sand, localities 2646Pr, 

5632a, 5631P, 563W, 5633P, 7054°, 9961 r. Shoal River 

formation, localities ?5079P, 5192P, ~9960P. 

Yoldia soror Gardner, n. sp. 

Plate IV, Figures 8-12 

Shell rather small for the genus, thin and very fragile, 

transversely ovate in outline, more attenuated and 

slightly gaping posteriorly, feebly inflated. Umbones 

small, well rounded, acutely pointed at their incurved, 

feebly opisthogyrate apices, slightly anterior. Lunule 

very narrow, lenticular, the margin sharply elevated 

toward the umbones but flattening distally. Escutcheon persisting the entire length of the posterior 

dorsal n1argin, narrow, delimited by a sharply incised 

groove, broken by a linear ridge running parallel to the 

groove and midway between it and the dorsal margin. 

Anterior dorsal margin very ofeebly convex, rounding 

abruptly into the broadly arcuate lateral margin. 

Posterior dorsal margin excavated, more produced 

than the anterior, the short lateral margin obtusely 

truncate. Base line horizontal medially, upcurved 

distally. External surface highly polished, retaining 

obscure traces of a concentric color banding, smooth 

except for incremental striae and a fine, faint concentric corrugation at the apices of the umbones. An 

anterior and a posterior area faintly indi~ated in some 

individuals by a change in the character of the color 

banding and of the incrementals. Ventral margins 

simple. Ligament entire, lodged in a short, rather 

wide, cuneate chondrophore directly beneath the 

umbones. Hinge teeth taxodont, slender, conic, 

acutely tapering but not hooked at their ex~remities, 

about 21 in the anterior series and 22 in the posterior, 

both series following parallel to the dorsal margin and 

thus forming a feebly concavo-convex hinge interrupted by the chondrophore. Muscle impressions 

and pallial sinus obscure because of the thin shell and 

highly polished interior. Anterior muscle scar rather 

large, rounded, placed well up under the distal 

extremity of the hinge. Posterior scar smaller and 

more angular, elongated parallel to the dorsal margin. 

Sfiil\ll\ 0-50-4 (142-A) 

Pallial sinus broad, ascending, not persisting to the 

median horizontal. Pallial line running close to the 

basal margin. 

Dimensions: Altitude, 5.6 millimeters; latitude, 

11.5 millimeters; diameter, 4.0 millimeters. 

Type: U.S. Nat. Mus. No. 352303. 

Type locality: No. 3748, Summerville mill race, 

Walton County, Fla. 

Yoldia soror Gardner, n. sp., is the closely related 

Shoal River analog of Y oldia frater of the Oak Grove 

and Chipola species. It differs in that it is relatively 

shorter and higher, the anterior and posterior portions 

of the shell are more nearly uniform in altitude, and 

the sculpture upon the umbones is more restricted or 

absent altogether. 

Occurrence: Shoal River formation, localities 

3856a, 3742°7 2238r, 3748P, 9957P, 10603°7 10608P. 

Superfamily ARCACEA 

Family LIMOPSIDAE 

Genus TRINACRIA C. Mayer 

1868. Trinacria C. Mayer, Catalogue systematique et descriptif 

des fossiles des terrains t€rtiaires que se trouvent au 

Musee Federal de Zurich, vol. 3, pp. 59, 63. 

Type: Trigonocoelia crassa Deshayes. (Eocene of 

the Paris Basin.) 

Shell small, equivalved, inequilateral, not gaping. 

Outline transversely ovate to trigonal. Umbones 

small, subacute, opisthogyrate, submedial or slightly 

posterior. Anterior extremity broadly rounded. 

Posterior portion of shell more or less sharply rostrate, the rostral angle well defined toward the umbones 

but flattening toward the ventral margin. External 

surface us-ually s:mooth except for incrementals. 

Basal margin not serrate. Ligament area amphidetic. 

Ligament alivincular, seated on a small trigonal, depressed area directly beneath the umbones and persisting almost to the inner margin of the hinge, thus 

interrupting the dental series. Anterior and posterior series discrepant., the anterior usually including 

the larger number of teeth. Teeth very small, taxodont. 1fuscle impressions usually obscure, placed 

well up toward the dorsal margins. Pallial line 

simple. 

Trinacria is a small group of restricted distribution. 

It has a moderate representation in the Eocene of continental Europe and is also present in the Eocene of 

the Gulf. It has not, however, been reported from 

strata younger than the Alum Bluff. One species and 

a subspecies occur in the Alum Bluff-Trinacria 

rneekii Dall, a not uncommon little bivalve in the 

Oak Grove but rare in the Shoal River, and its subspecies Trinacria parameekii from the Chipola. 

Altitude of adult approximately three-fifths the latitude. 

Trinacria meekii Dall. 

Altitude of adult less than three-fifths t.he latitude. 

Trinacria meekii parameekii Gardner, n. subsp. 
22 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Trinacria meekii Dall 

Plate IV, Figure 1 

1898.' Trinacria meekii Dall, Wagner Free In st. Sci. Trans. 

vol. 3, pt. 4, p. 604, pl. 32, fig. 17. 

Dall describes this species as follows: 

Shell small, solid, moderately convex, sculptured only with 

fine concentric lines; anterior end rounded, posterior somewhat 

shorter, more pointed; beaks low, with (in the adult) an almost 

linear depressed amphidetic area, interrupted by an oblique 

impressed subtriangular ligament pit which, though external, 

interrupts also the line of teeth; interior smooth, muscular impressions large, not bounded by an elevated line; pallial line 

slightly indented below the posterior adductor scar; there are 

about eight anterior and six posterior teeth, small and delicate; 

basal margin smooth and nearly straight. Longitude 5.5, 

altitude 3.2, diameter 2.2 millimeters. 

Type: U. S. Nat. Mus. No. 1:-35824. 

Type locality: Oak Grove, Yell ow River, Okaloosa 

County, Fla. 

The Oak Grove forms run a little larger and a little 

heavier than the Chipola. The altitude is relatively 

higher, the umbones are more centrally placed, the 

posterior extremity is less nasute, and the base line not 

quite so straight as in the Chipola species. However, 

the end men1bers at the two horizons distinctly overlap 

so that the differences can not be given full specific 

value. 

Occurrence: Oak Grove sand, localities 2646°, 5632P, 

5631 r, 5633r, 7054r. Shoal River formation, locality 

3748r. 

Trinacria meekii param eekii Gardner, n. subsp. 

Plate IV, Figures 2-5 

Shell small, thin, quite highly inflated, transversely 

ovate in outline. Umbones small, narrow, flattened 

upon their summits, acute at the tips, opisthogyrate, 

slightly posterior. Anterior dorsal margin approximately horizontal and parallel to the base, the posterior 

obliquely arcuate. Anterior extremity very broadly 

rounded, the posterior obtusely pointed. Base line 

approximately horizontal. Shell obscurely rostrate 

behind, the angle rather well defined toward the 

umbones but flattening toward the base. External 

surface sculptured only with fine incremental striae, 

emphasized here and there by a resting stage. Ventral 

margins smooth within. Ligament external. Ligament a.rea exceedingly narrow, amphidetic. Ligament pit small, trigonal, depressed, subumbonal, 

elongated parallel to the anterior dorsal margin, produced almost to the inner n1argin of the hinge and 

thus interrupting the dental series. Teeth small, 

delicate, oblique to the margin, somewhat cuneate, 

the angle directed toward the umbones, 7 in the 

anterior series and 5 in the posterior, including the 

denticles at the extremities of each series. Muscle 

iinpressions and pallial line very obscure; scars 

moderately large for the size of the shell and placed 

well up at the distal extremities of the teeth. Pallial 

line simple, parallel to the basal margin and not far 

distant from it. 

Dimensions of right valve: Altitude, 2.6 millimeters; latitude, 4.5 millimeters; semidiameter, 1.4 

millimeters. Dimensions of left valve: Altitude, 2. 7 

millimeters; latitude, 4.6 millimeters; semidiameter, 

1.4 millimeters. 

Cotypes: U.S. Nat. Mus. No. 352304. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Chipola River, Calhoun County, Fla. 

Trinaeria meekii parameekii is smaller, thinner, 

relatively higher, and more angular than Trinaeria 

meekii Dall from the Oak Grove. The umbones are 

more inclined to be posterior in the Chipola species, 

and the base line is usually straighter. 

Occurrence: Chipola formation, localities 2213P, 

3419r, 7151 P. 

Family ARCIDAE 

Genus ARCA (Linnaeus) Lamarck 

1758. Linnaeus, Systema naturae, lOth ed., p. 693. 

1799. Lamarck, Prodrome d'une nouvelle classification des 

coquilles: Soc. hist. nat. Paris Mcm., p. 87. 

Type: Area noae Linnaeus. (Recent in the Mediterranean.) 

Shell equivalve, oval or subquadrate. Valves 

closed or gaping ventrally. Sculpture generally 

heavy and radial. Hinge line long, straight, furnished 

with numerous transverse teeth. Umbones prominent, incurved, prosogyrate, separated by a rhomboidal ligamen tal area scarred with cartilage grooves. 

Margins smooth or cr~nulate. Pallial line simple. 

Adductor impressions subequal, strongly marked. 

A genus represented by about 500 fossil species, 

which range from the Silurian onward, and by about 

150 recent species which are widely distributed in the 

warmer seas from between tides to abysmal depths. 

The abundance of the representatives of this 

genus, their wide range in time and place, together 

with their rather more than normal sensitiveness to 

environmental conditions, make them of peculiar 

importance in stratigraphic work. 

The Area fauna of the Alum Bluff includes 19 

species. About two-thirds of this number occur in 

the Chipola, though only 8 of the 13 have not been 

reported from the Oak Grove as well. All three 

species of Area s. s. are found in the Chipola, two 

in the Oak Grove, and none at all in the Shoal River. 

The two forms that occur in the Oak Grove-Area 

oeeidentalis and Area umbonata-reappear, however, 

in the later faunas and persist to the present day. 

All four Barbatias, too7 are present in the Chipola, 

though three of them continue into the Oak Grove 

and one-Area adamsi, which still persists in the 

living fauna--occurs also in the Shoal River. Neither 

is the fourth species-Area reticulata-diagnostic, for 
PRIONODESMACEA AND ANOMALODESMACEA 23 

it is found in both the later Tertiary and the Recent 

faunas. Diluvarea, which is represented by 12 species, 

seems to be more sensitive and includes the more 

abundant and characteristic forms. Only a single 

species of Diluvarea occurs at more than one horizon 

and that form-Area hypomela-is known in the Oak 

Grove from a single individual. The other six forms 

are all peculiar, though Area santarosana geraetera has 

only subspecific value. Area staminata seems to be 

restricted to the type locality at Alum Bluff. The 

diminutive Area mikkula is the most abundant 

and widespread of the Chipola species. The four 

Diluvarcas from the Oak Grove are all allied to Chipola 

forms, though only Area hypomela is specifically 

identical. Area dodona, the most abundant of the four, 

is closely related to Area hypomela. Area santarosana 

is represented in the Chipola by a subspecies, whereas 

Area eardioides is a very close analog of the Chipola 

Area initiator and occupies a similar minor position in 

the fauna. The most prolific of the two Shoal River 

Diluvarcas is a probable analog of Area santarosana, 

whereas the other finds its closest affinities among 

the Areas of the upper bed at Alum Bluff. 

Shell equivalve, transversely elongated, commonly rectangular; 

sculpture of crowded, irregular radials or, more rarely, evenly 

cancellated or granose: 

Radials crowded and irregular: 

Posterior keel well defined; umbones widely sep- arated _______________________________ _ Areas. s. 

Altitude of adult exceeding 10 millimeters; 

radial sculpture not conspicuously delicate: 

Posterior keel obtuse; concentric sculpture 

not strong enough to cancellate the surface. 

Area oecidentalis Philippi. 

Posterior keel acute; concentric sculpture 

strong enough to cancellate the surface. 

Area umbonata Lamarck. 

Altitude of adult not exceeding 10 millimeters; 

radial sculpture conspicuously delicate. 

A rca parat?:na Dall. 

Posterior keel obscure or obsolete; umbones not 

widely separated ____________ _ Barbatia (Plagiarea). 

Shell compressed; latitude of adult exceeding 25.0 

millimeters. 

Barbatia (Plagiarca) marylandiea Conrad. 

Shell moderately inflated; latitude of adult not 

exceeding 25.0 millimeters. 

Barbatia (Plagiarea) phalaera Dall. 

Shell small, rudely rectangular; radials regular in size and 

spacing, evenly cancellated or granose __ Barbatia (A car). 

Radials evenly cancellated. 

Barbatia (Aear) retieulata Gmelin. 

Radials granose. 

Barbatia (Fossularca) adamsi (Shuttleworth) Dall. 

Shell commonly inequivalve, transversely elongated, rudely 

quadrate or ovate-trigonal in outline; radial sculpture regular. 

Diluvarea. 

Shell transversely elongated or ovate-trigonal; latitude, 

if ovate-trigonal, exceeding 10.0 millimeters: 

Shell transversely elongated, the altitude in the adult 

forms rarely equaling three-fourths the latitude, the 

number of radials in such forms normally exceeding 32: 

Radials normally not exceeding 32: 

Latitude of adult shell exceeding 12.0 millimeters _____ Diluvarea latidentata ( Dall). 

Latitude of adult shell not exceeding 12.0 

millimeters. 

Diluvarca mikkula Gardner, n. sp. 

Radials normally exceeding 32: 

Shell approximately twice as broad as it is 

high; radials on anterior and anteromedial portion of shell mesially sulcate: 

Radials on postero-medial portion of 

shell mesially sulcate; latitude of 

adult exceeding 25.0 millimeters. 

Diluvarea hypomela (Dall). 

Radials on postero-medial portion of 

shell simple; latitude of adult not 

exceeding 25.0 millimeters. 

Diluvarea aeompsa (Dall). 

Shell less than twice as broad as it is high: 

Radials mesially sulcate; each half radial 

on the adult shell bisected by a shallow 

groove ______ _ Diluvarea dodona(Dall). 

Radials simple, not mesially sulcate. 

Diluvarea strebla Gardner, n. sp. 

Shell rudely quadrate or ovate-trigonal in outline, the 

altitude in the adult forms normally equaling or 

exceeding three-fourths the latitude; radials 27 to 

33: 

Radials usually 28 or 29, those on the anterior 

portion of the adult shell not mesially sulcate. 

Diluvarea staminata (Dall). 

Radials usually 30 to 32, those on the anterior 

portion of the shell mesially sulcate: 

Shell not as high as it is broad: 

Shell approximately three-fourths as 

high as it is broad. 

Diluvarea santarosana (Dall). 

Shell approximately seven-eighths as 

high as it is broad; umbones conspicuously narrow and elevated. 

Diluvarea santarosana geraetera Gardner, n. subsp. 

Shell approximately as high as it is broad. 

Diluvarea waltonia Gardner, n. sp. 

Shell ovate-trigonal; latitude not exceeding 10.0 millimeters; sculpture markedly discrepant in the two valves: 

Latitude of adult rarely exceeding 5.5 millimeters. 

Diluvarca (Cunearea) initiator (Dall). 

Latitude of adult usually exceeding 5.5 millimeters. 

Diluvarea (Cunearca) eardioides Gardner, n. sp. 

Subgenus ARCA s.s. 

Type: Area noae Linnaeus. (Recent jn the Mediterranean.) 

The typical Areas are transversely elongated, rudely 

quadrate, commonly irregular in outline, inequilateral, 

and gaping anteriorly. The beaks .are prominent, 

placed well forward, and separated by a wide cardinal 

area scarred with oblique, discontinuous ligament 

grooves. The hinge line is straight; the teeth are 

numerous, subequal, and approximately at right angles 

to the margin. 

Area occidentalis Philippi 

1847. Area oecidentalis Philippi, Abbildungen und Beschreibungen Conchylien, vol. 3, p. 29, pl. 4, fig. 4. 

1917. Area oecidentalis Philippi. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 8, pl. 1, figs. 8, 9, 10, 11. 
24 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

1917. Area oecidentalis Philippi. Maury, Bull. Am. Paleontology, vol. 5, No. 29, p. 163, pl. 29, fig. 3. 

Area noae of many authors, not of Linnaeus. 

Philippi described this species in 184 7 as follows: 

A. testa elongato-oblonga, subquadrangula; latere antico 

breviusculo, angulo fere recto terminato; postico emarginato; 

carina obtusa ab a pice decurrente; costis regularibus, prominentibus, interstitia longitudinaliter striata subaequantibus; medianis 

parum minoribus; area dorsali mediocri; ligamento illam maxima 

ex parte occupante. Long. 22"'; alt. 1 0"'; crass. 11 "'. 

Patria: lndiae Occidentales; ad Cubam ligit cl. Pfeiffer. 

Type locality: West Indies. 

The typical recent specimens are large, transversely 

elongated shells covered with a heavy epidermis. The 

outline is conspicuously irregular. The umbones are 

rather small but acute, compressed, widely separated 

and placed well within the anterior third. The dorsal 

margin is straight and marks the maximum latitude of 

the shell. From the anterior extremity of the hinge 

the lateral margin slopes backward to the shallow 

byssal gape. The posterior portion of the ventral 

margin is broadly convex, the posterior lateral margin 

quite strongly concave. The rostrum is well defined 

from the umbones to the outer margin. The umbonal 

sulcus is feebly developed and broadens rapidly toward 

the ventral margin, coinciding at the base with the 

byssal gape. The radial sculpture is very irregular. 

As a rule there are 6 to 8 strong well-rounded cords 

on the anterior portion of the shell, with or without 

intercalated linear secondaries, and 12 or 15 finer and 

more closely spaced radials, usually with filamentous 

secondaries upon the median depression. Between 

the sulcus and the posterior keel the primaries are 

low, broad, in many specimens mesially furrowed, 

about 10 in number, and separated by interspaces of 

varying width in which from 1 to 5 secondaries 11re 

developed. The sculpture between the keel and the 

dorsal margin is the coarsest upon the shell. The 

number of primaries is about half a dozen, and they 

are so disposed that there is quite an area between the 

outer primary and the dorsal margin, which is either 

finely striated radially or sculptured only with the 

incrementals which are best developed upon this 

portion of the shell. The cardinal area is broad and 

somewhat kite-shaped, the ligament area more restricted than the cardinal, especially behind the 

umbones, and scarred with ir_regular furrows conr 

verging toward the umbones. The hinge margin is 

very finely and sharply serrate, the lateral and ventral 

margins obscurely crenulated in harmony with the 

external sculpture. The Oak Grove specimens are 

young but appear to be identical with the Recent 

species. 

The date of publication of D'Orbigny's Area 

barbadensis is uncertain, so that for the present it is 

unnecessary to supplant Philippi's well-known name. 

Area paratina Dall is similar in general characters 

to the young oeeidentalis but is a more delicate shell 

and much more finely sculptured. Area umbonata 

Lamarck is more inflated in the umbonal region, is 

more sharply rostrate, and develops a more imbricated 

ornamentation. 

The occurrence of this tropical species in the Oak 

Grove is significant. Though present in the Bowden 

of Jamaica it has not been recognized in Florida in 

strata older than the Caloosahatchee. 

The Recent representatives have a wide geographic 

distribution, though they are restricted to the shallow 

waters, usually less than 20 fathoms. The species has 

been reported from Hatteras to Santa Marta and 

Cartagena and east to Bermuda. The possession 

of a byssus by which they can attach themselves to 

foreign objects gives to this group a very effective 

means of dispersion. 

Occurrence: Oak Grove sand, localities 2646 r (juveniles), 5632 r (juveniles). Shoal River formation, 

localities 10603P, 10608r. 

Outside occurrence: Miocene: Moin Hill, Costa 

Rica; Bowden beds, Jamaica; Gurabo formation, 

Santo Domingo. Pliocene: Caloosahatchee beds, 

Florida. Pleistocene: Florida and the West . Indies. 

Recent: Cape Hatteras to Cartagena and east to 

Bermuda in 1 to 20 fathoms. 

Area umbonata Lamarck 

1819. Area umbonata Lamarck, Histoire naturelle des animaux 

sans vertebres, vol. 6, p. 37. 

1835. Area umbonata Lamarck, idem, 2d ed., vol. 6, p. 462. 

(Synonymy in part excluded.) 

1847. Area umbonata Lamarck. Philippi, Abbildungen und 

Beschreibungen Conchylien, vol. 3, p. 14, pl. 4, figs. 

3a-c. 

1873. Barbatia bonaezyi Gabb, Geology of Santo Domingo, 

Am. Philos. Soc. Trans., vol. 15, p. 254. 

1887. Area imbrieata Bruguiere. Heilprin, Wagner Free Inst. 

Sci. Trans., vol. 1, p. 118. 

1887. Area listeri? Philippi. Heilprin, Wagner Free Inst. Sci. 

Trans., vol. 1, p. 118. 

1889. Area imbrieata Bruguiere. Dall, "Q. S. Nat. Mus. Bull. 

37, p. 40. 

1917. Area umbonata Lamarck. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 8, pl. 1, figs. 12-17. 

1917. Area umbonata Lamarck. Maury, Bull. Am. Paleontology, vol. 5, No. 29, p. 163, pl. 30, fig. 11. 

Lamarck described this species in 1819 as follows: 

A. testa transversim oblonga, ventricosa, angulato-sinuata 

decussatim substriata; umbonibus magnis, arcuatis; latere 

postico brevissimo. 

Type locality: Jamaica. (Recent.) 

Area umbonata is a shell of moderately large size 

and very irregular outline. The umbones are prominent, widely separated, acute at their summits, 

feebly prosogyrate, and placed within the anterior 

third. The hinge line is straight and extends to the 

anterior extremity of the shell but not to the posterior. 

The anterior margin between the dorsal area and the 

byssal opening is smoothly rounded. The opening is 

rather wide and occupies one-third or more of the 

margin between the anterior extremity of the hinge 

and the posterior keel. There is a decided vertical 
PRIONODESMACEA AND ANOMALODESMACEA 25 

expansion of the shell behind the opening and the 

posterior keel, which is produced backward beyond 

the posterior extremity of the hinge. The posterior 

lateral margin is little or not at all constricted. The 

surface ornamentation is finely and rather evenly 

cancellate, the radials standing out more sharply 

anteriorly, whereas on the posterior area they do not 

number more than half a dozen and are much co3J'Ser 

than upon the medial or anterior portions of the shell. 

The cardinal area is wide and smoothly convex, and 

the ligament occupies the entire area. There are two 

deep grooves diverging beneath the umbones and 

forming a small, diamond-shaped area in the double 

valves. Other shorter grooves to the number of 

half a dozen are developed near the hinge line. The 

hinge is very finely serrate within the limits of the 

pallial line, which follows close to the outer margin. 

The inner margins are simple. 

Area umbonata is more irregular in outline and more 

regular in ornamentation than any of the other 

species of Area s. s. reported from the Alum Bluff. 

The umbonal inflation is also higher and the rostral 

keel sharper than in either Area oceidentalis or Area 

paratina. 

The Alum Bluff material is very meager and not 

sufficient to prove without question the identity of the 

Tertiary and Recent species. The relationship is 

certainly close, and the apparently wider byss.al gape 

of the Tertiary forms may easily be due to individual 

variation or to a slight immaturity. 

The Recent representatives inhabit the shallow 

waters along the east coast from Hatteras to southern 

Brazil and east to Bermuda. 

Occurrence: Chipola formation, localities 2212r, 

2213r, 2564r, 341gr. Oak Grove sand, localities 264W, 

5632r. 

Outside occurrence : Miocene : '' Tampa silex beds,'' 

Florida; Moin Hill, Costa Rica, and the Gurabo formation, Dominican Republic. Pleistocene: Florida 

and the West Indies. Recent: Cape Hatteras to 

southern Brazil in less than 50 fathoms. 

Area paratina Dall 

Plate V, Figure 5 

1898. Area paratina Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 621, pl. 33, fig. 14. 

1917. Area paratina Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 7, pl. 1, figs. 5-7. 

Dall describes this species as follows: 

Shell elongated, not very thick or high, not much distorted 

but with a variable byssal gape, inequilateral, the beaks at or 

near the anterior fourth; moderately alate in front and behind; 

beaks low, pointed, not inflated, their apices slightly prosogyrate, cardinal area long, narrow, lozenge-shaped, flattish, 

with longitudinal striae, the site of the resilium marked on each 

valve by two grooves forming a small triangle, within which 

are traces of the inception of other grooves; sculpture chiefly 

of fine radial riblets overrunning and somewhat imbricated by 

not prominent lines of growth; the radials which end on the 

margin of the byssal foramen are perceptibly finer than the 

rest, those on the posterior dorsal slope are more or less fasciculated, the ends of the fascicles dentating the posterior margin; 

on the dorsal anterior part the riblets increase somewhat in 

size but are not fasciculated; the dorsal border in front is 

anterior to the rest of the margin; between the dorsal posterior 

extreme and the ventral posterior angle there is often an irregular 

but not deep emargination; the borders of the byssal foramen 

are irregularly emarginate; interior smooth, the margin denticulated by the sculpture except at the foramen; hinge line 

straight, minutely denticulate; the teeth in the center smaller, 

those toward the ends inclined outward slightly, 'above, and 

a little larger; there are about 23 anterior and 40 posterior 

teeth, with no marked hiatus between the series. Longitude of 

shell, 28 millimeters; altitude of hinge line, 8.5 millimeters; 

of beaks, 10 millimeters; diameter at the umbonal part, 10 

millimeters. It is quite possible that the shell grows to a considerably larger size. 

This species is distinguishable at once from the A. oecidentalis of the same size by its uniformly more delicate and much 

more numerous ribs and by its greater length iri proportion to 

its heig.ht. It is also usually less alate behind and of more 

uniform, undistorted shape. Differences of form and proportion 

seem to separate it sufficiently from A. subprotraeta Heilprin. 

Type: U.S. Nat. Mus. No. 114786. 

Type locality: No. 2213, 1 mile below Baileys Ferry, 

Chipola River, Calhoun County, Fla. 

The young of Area umbonata Lamarck are more 

inflated and more sharply rostrate, and the sculpture is 

relatively coarser and more evenly fluted. The young 

of Area oecidentalis are even more similar in general 

characters but al:e less delicate and less finely sculptured. Area yaquensis Maury, so common in the 

Cercado and Thomonde formations of the Dominican 

Republic is less elongated trans,ersely. 

Occurrence: Chipola formation, localities 10609a, 

2213~ 3419~ 2211~ 

Subgenus BARBATIA Gray. 

1842. Barbatia J. E. Gray. Synopsis of the contents of the 

British Museum, p. 81. 

Type: Area barbata Linnaeus. (Recent in the 

Mediterranean.) 

Gray describes this subgenus as follows: 

The Barbatia are elongated shells, covered with a hairy 

periostraca; the teeth on the middle of the line are small, of the 

ends large and oblique. 

Dall adds the following remarks: 12 

The type form of this group is tolerably regular and seldom 

deformed, like the typical Arks, from the anfractuosities of its 

station; the reticulated sculpture shows few irregularities; the 

cardinal area is narrow with numerous grooves for the resilium, 

which form a series of elongated concentric lozenges on the 

area; the shell is not conspicuously truncate or keeled; the teeth 

are small and vertical in the middle of the series and toward 

the end diverge distally ~d become larger and more distant. 

In some species these distal teeth are often broken up, like 

those of Cueullaea, but this feature is not constant in the species. 

Several groups or sections are recognizable, though they merge 

into one another through their peripheral species. 

12 Dall, W. H., Contributions to the Tertiary fauna of Florida: Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 614, 1898. 
26 THE MOLLUSCAN FAUNA OF THE ALUl\i BLUFF GROUP OF FLORIDA 

Section PLAGIARCA Conrad 

1875. Plagiarca Conrad. Kerr, Rept. Geol. Survey North 

Carolina, vol. 1, app. A, p. 4. 

= Calloarca Dall and authors. (Type: Area candida 

Gmelin.) 

Not Calloarca Gray, 1857, Annals and Mag. Nat. Hist., 

2d ser., vol. 19, p. 369. (Type: Barbatia alternata 

Reeve.) 

Type: Barbatia carolinensis Conrad. (Cretaceous 

(Ripley formation) of North Carolina.) 

The monotype of Gray's Calloarca is Area alternata 

Reeve, a rare w.est coast species of the Acar group. 

As no other species can serve as the type, Galloarca 

n1ust of necessity become a synonym of Acar. Litharea Gray, 1842, was founded with Byssoarca lithodomus Sowerby as the monotype, a forn1 which is 

probably nothing more than an Area candida much 

distorted by growth in a Lithodom118 burrow. In 

view of the uncertainty and the misfortunes of employing such a type, Litharca may well be rejected 

in favor of Conrad's clearly defined Plagiarca. 

Conrad defines this section as follows: 

Shell with a straight hinge margin terminating in an angle, 

narrow cardinal area, having minute close angulated lines; 

cardinal teeth very oblique without angles toward the interior 

margin; short; anterior series with one or two teeth comparatively large, slightly angulated in the middle and very oblique. 

Barbatia (Plagiarca) marylandica Conrad 

1840. Byssoarca marylandica Conrad, Fossils of the medial 

Tertiary of the United States, p. 54, pl. 29, fig. 1. 

1863. Barbatia (Byssoarca) maryland·ica Conrad, Acad. Nat. Sci. 

Philadelphia Proc. for 1862, p. 580. 

1864. Barbatia marylandica Conrad. Meek, Check list of the 

invertebrate fossils of North America: Smithsonian 

Misc. Coli. No. 183, p. 6. 

1894. Barbatia marylandica -Conrad. Whitfield, U. S. Geol. 

Survey Mon. 24, p. 48, pl. 7, figs. 2-4. 

1898. Barbatia (Calloarca) marylandica Conrad. Dall, Wagner 

Free Inst. Sci. Trans., vol. 3, pt. 4, p. 623. 

1898. Barbatia ( Calloarca) candida Gmelin. Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 626 (part). 

Not Area candida Gmelin, 1792, and authors. 

1898. Barbatia (Calloarca) marylandica Conrad. Dall, U. S. 

Nat. Mus. Bull. 90, p. 119, pl. 4, fig. 3. 

1904. Area (Barbatia) marylandica Conrad. Glenn, Maryland 

Geol. Survey, Miocene, p. 392, pl. 106, fig. 7. 

1917. Area marylandica Conrad. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 14, pl. 3, figs. 5-7. 

Conrad described this species in 1840, as follows: 

Shell oblong, compressed, thin, with very numerous radiating 

granulated striae; beaks .not prominent; base much contracted 

or emarginate anterior to the middle; posterior side dilated, 

the superior margin very oblique and emarginate; extremity 

angulated, and situated nearer to the line of the hinge than to 

that of the base; cardinal teeth minute, except toward the 

extremities of the cardinal line, where they are comparatively 

very large and oblique; inner margin entire. 

Type: Academy of Natural Sciences of Philadelphia. 

Type locality: "Cliffs of Calvert," Md. (Calvert 

formation). 

The Chipola individuals seem to be a little higher 

relatively, a little more regular in outline, and not 

quite so finely sculptured as those from Maryland and 

New Jersey. The radials upon the anterior portion of 

the shell are quite sharply elevated and granulated and 

separated by interspaces of approximately their own 

width. On the medial portion of the shell the primaries are finer and less uniform in size and spacing 

and toward the posterior portion of the shell are often 

me~ally sulcate. Secondaries are quite regularly 

intercalated, making a rather crowded ornamentation. 

Over the keel the radials are very low and irregular, 

but strengthen again behind the keel, are more sharply 

corrugated by the incrementals, and are, as a rule, 

mesially sulcate. The cardinal area is narrow and 

furrowed with four or five discontinuous, more or less 

undulatory grooves. The hinge is extremely narrow 

and finely serrate medially but widens distally, 

especially behind the umbones. There are about four 

relatively coarse anterior teeth and half a dozen 

posterior. The inner margins are simple. 

Occurrence: Chipola formation, localities 2212P, 

2213P, 2564_r, 341W, 2211r. Oak Grove sand, localities 

2646r, 7054r, 10659r. Shoal River formation, locality 

106031". 

Outside occurrence: Miocene: "Tampa silex beds" 

at Ballast Point, Fla.; the marls of Jericho, Cumberland County, N. J., and beds at Plum Point, Calvert 

Cliffs, and Centerville, Md. 

Juveniles referred by Dall to Area candida Gmelin 

should be included under this species. The young 

candida are less finely and more sharply threaded 

than young marylandica. Area candida is a denizen 

of the shallow wa.ters along the east coast from Cape 

llatteras to southern Brazil. 

Barbatia (Piagiarca) phalacra Dall 

Plate V, Figure 6 

1898. Barbatia (Calloarca) phalacra Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 626, pl. 33, fig. 3. 

1917. Area phalacra Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 16, pl. 3, fig. 10. 

Dall describes this species as follows: 

Shell thin, moderately convex, equivalve, inequilateral; 

the prosogyrate beaks within the anterior fourth low and somewhat compressed; sculpture of very numerou~ fine, even, 

mostly dichotomous riblets without nodules or reticulation over 

the whole shell, crossed only by feeble incremental lines; cardinal 

area very narrow with a few longitudinal grooves; hinge teeth 

small, short, and vertical mesially without any gap in the series, 

distally longer, larger, and more oblique; hinge line tt of the 

whole length; internal margin of the valves smooth, byssal 

gape inconspicuous. Longitude 23.5, altitude 11, diameter 

9 millimeters. 

This is a very modest and neat little species which does not 

seem identifiable with any of the others. It is perhaps 

nearest to B. mississi1Jpiensis Conrad but is smaller, less 

flattened, and more regular. 

Type: U.S. Nat. Mus. No. 135831. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 
PRIONODES.MACEA AND ANO.MALODES.MACEA 27 

There is a bewildering amount of age variation in 

this species. The young are very finely and evenly 

threaded radially. Later on the radials become less 

uniform in size and spacing and tend to bifurcate. 

Secondaries are commonly intercalated, and the 

resulting ornamentation is quite similar to that of the 

less inflated Barbatia marylandiea Conrad. The 

juvenile uniformity of sculpture persists much longer 

in the two individuals from Oak Grove than in the 

Chipola individuals and may, with the acquisition of 

further material, prove a character of taxonomic value. 

Occurrence: Chipolaformation,locality2213P. Oak 

Grove sand, locality 2646r. 

Section ACAR Gray 

1857. Acar J. E. Gray, Annals and Mag. Nat. Hist., 2d ser., vol. 

19, p. 369. 

Type: Area gradata Broderip and Sowerby. (Recent 

off the west coast of Mexico and Central America.) 

Shell small, solid, inequilateral, transversely elongated, rectangular, rostrate behind; surlace normally 

cancellate; ligament area rhomboidal and, for the 

most part, opisthodetic, more restricted anteriorly 

than the cardinal area. 

Area donaelformis, commonly cited as the type of 

this section and described by Reeve from Mozambique, is not included in Gray's original list of three 

species. Area gradata was designated the type by 

W oodring.13a 

Barbatia (Acar) reticulata Gmelin 

1784. Area retieulata Chemnitz, Conchylien-Cabinet, vol. 7, p. 

193, pl. 54, fig. MO. 

1792. Area retieulata Gmelin, Systema naturae, vol. 6, p. 3311. 

1819. Area domingensis Lamarck, Histoire naturelle des 

animaux sans vertebres, vol. 6, p. 40. 

1898. Barbatia (Aear) retieulata Gmelin. Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 629. 

1917. A rca reticulata Gmelin. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 20, pl. 4, figli. 8-12. 

1917. Barbatia (Aear) reticulata Gmelin. Maury, Bull. Am. 

Paleontology, vol. 5, No. 29, p. 166, pl. 30, fig. 16. 

1919. Area (Acar) retieulata Gmelin. Harris, Bull. Am. 

Paleontology, vol. 6, No. 31, p. 55, pl. 22, figs. 18, 19. 

Gmelin described this species in 1792 as follows: 

A. testa subrhomboidea decussatim striata alba: natibus 

approximatis, vulva cordata. 

List. Conch., t. 233 f. 67. 

Martini Besch., Berl. Naturf., 3, t. 6, f. 9. 

Chemn. Conch., 7 t. 54 f. 540. 

Habitat * * * arcae Noae affinis; utrum hujus, an 

sequentis familiae? 

Type locality: Not definitely known. 

The shell is small, heavy, inflated, subrhomboidal, 

and acutely rostrate posteriorly, thus suggesting in 

outline and dimensions a very solid and overgrown 

Barbatia adamsi. The umbones are rather broad, antaa This report was already in proof when Woodring's" Miocene mollusks from 

Bowden, Jamaica" (Carnegie Inst. Washington Pub. 366, 1925), was published. I 

have taken advantage of Woodring's work to the extent of making a number of 

changes in the nomenclature, but I have been unable to offer any discussion of 

these changes. 

terior in position, strongly incurved, prosogyrate, 

and proximate. The external surlace is sharply 

cancellated by conspicuously elevated radial cords 

separated by deep grooves of approximately their 

own width and crossed at regular intervals by numerous concentric ridges or laminae which tend to nodulate 

the radials at their intersection. Between the concentric ridges the interradial grooves appear as deep 

pits. Along the posterior keel the concentric sculpture is commonly conspicuously laminar or scabrous, 

and this character is maintained to a certain extent 

across the posterior area. The cardinal area is 

extremely narrow, expanding slightly beneath the 

umbones and scarred with a few irregular, commonly 

discontinuous grooves rudely parallel to the hinge 

line. The hinge is rather short and rather coarsely 

dentate distally, .with irregular and in some specimens 

obsolete medial serrations. The inner margin of the 

valves is finely dentate. 

Two individuals serve to establish the presence of a 

species unusually well characterized by outline and 

ornamentation. 

Occurrence: Chipola formation, locality 2213r. 

Shoal River formation, locality 10608r. 

Outside occurrence: Eocene: Claiborne group of Mississippi and Texas(?) . Miocene: " Tampa silex beds" 

of Florida; Miocene of Santo Domingo and Jamaica. 

Pliocene: Caloosahatchee formation of Florida. Pleistocene: Florida and the West Indies. Recent: Cape 

Hatteras to the Gulf of Campeche and east to Bermuda. 

The Recent members have a wide geographic and 

bathymetric range. Off Hatteras the form occurs 

both in shallow water and in deep water up to 287 

fathoms. Elsewhere in its range along the east 

coast from Hatteras to the Gulf of Campeche and 

east to Bermuda it is restricted to the shallow waters. 

The species has also been reported from the west 

coast from San. Diego to Ecuador, but this is probably 

a closely allied and not an identical form. 

Section FOSSULARCA Cossmann 

1887. Cossmann, Catalogue illustre des coquilles fossiles de 

l'~ocene des environs de Paris, vol. 2, p. 142. 

Type: .Area quadrilatera Lamarck. (Eocene of the 

Paris Basin.) 

Cossmann defines this section as follows: 

Coquille mince, oblongue, subquadrangulaire, subequilaterale, 

inequivalve, a surface treillisee; crochets ecartes; aire ligamentaire etroite, portant sous le crochet une petite fossette 

triangulaire bien limitCe, au fond de laquelle se distinguent 

de petits sillons perpendiculaires au bord; dents presque 

egales, plus ou moins obliques. 

Shell thin, oblong, subquadrate, subequilateral, 

inequivalve. Sculpture reticulate. Umbones separated by a narrow cardinal area grooved parallel 

to the hinge line. Ligament restricted to a minute 

vertically striated diamond-shaped area directly beneath the beaks. Teeth subequal, more or less 

oblique. 
28 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Barbatia (Fossularca) adamsi (Shuttleworth MS.) Dall 

Plate V, Figures 1-4 

1845. Area eoelata Conrad, Fossils of the medial Tertiary of 

the United States, p. 61, pl. 32, fig. 2. 

Not A1·ea eoelata Reeve, 1844. 

1886. Area adamsi Shuttleworth. Dall, Harvard Coll. Mus. 

Comp. Zoology Bull., vol. 12, p. 243. 

1888. Area (A car) adamsii Shuttleworth MS.? Smith, E. A., 

Linnaean Soc. Jour. Zoology, vel. 20, p. 499, pl~ 30, 

figs. 6, 6a. 

1898. Barbatia (Fossularea) adamsi (Shuttleworth) Smith. Dall, 

Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 629. 

1917. Area adamsi (Shuttleworth) Smith. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 22, pl. 4, 

figs. 16-18, pl. 5, fig. 1. 

Conrad described this form in 1845 as follows: 

Trapezoidal, disk widely and not profoundly contracted; 

ribs numerous, alternated toward the base, tuberculated, 

aculeated anteriorly and posteriorly; posterior slope depressed; umbo acutely angulated behfnd; basal margin 

slightly arched; posterior margin obliquely truncated; beaks 

approximate. Locality, "Wilmington, N. C. 

Dall described this species in 1886 as follows: 

This species is very common in shallow water throughout 

the West Indies and extends northward nearly or quite to 

Cape Hatteras. Its simulated ribs of trailing blisters give it 

a remarkably similar appearance to Area lactea, which, however, 

has real ribs. There is a dwarf, very short squarish variety, 

which from its greater proportional diameter (though not 

otherwise different) would at first he separated as distinct 

and which may be called Area adamsi var. eonradiana. 

Figured specimen: U. S. Nat. Mus. No. 325489 

(Wilmington, N. C.). 

Type locality: West Indies. 

Though this species was nmned by Shuttleworth 

in the early fifties, and though it is widely distributed, 

no record of any published description or figure has 

yet been found. The name appears in seV"eral check 

lists by Beau, Krebs, and others, but Dall seeJns to 

haV"e been the first to give any criteria for its identification. The formal Latin description of Smith 

was not published until two years later. 

The shell is unusually distinctive and may be 

readily recognized by the trapezoidal outline, the 

contraction of the basal margin, the dainty cancellated 

sculpture with its riblets formed of hollow flutings, 

the transverse ligamenta} grooves confined within a 

small diamond-shaped area directly beneath the 

umbones, and the well-defined n1uscular in1pressions 

mounted on raised ridges which converge dorsally 

beneath umbones. The measurements given by 

Smith are: Longitude, 12 millimeters; altitude, 

7.5 millimeters; diameter, 7.5 millin1eters. 

There are no characters by which the Alum Bluff 

forms rnay be separated from the Recent. In most 

of the individuals, however, the sculpture is more or 

less decorticated, leaving a roughened limy surface. 

The Recent members occur in considerable abundance 

from Hatteras to Fernando de Noronha, Brazil, in 

waters 35 fathoms in greatest depth. The species 

has also been reported from Bermuda. 

Occurrence: Chipola formation, localities 2213c, 

9994r, ~7468. Oak Grove sand, localities 2646r, 

5632r. Shoal River formation, localities 9957r, 

5618r. 

Outside occurrence: Miocene: Bowden formation, 

Jamaica; Yorktown formation, Virginia; Duplin 

formation, North Carolina, South Carolina, Georgia. 

Pliocene: Waccamaw formation, South Carolina; 

Caloosahatcheeformation, Florida; Croatan formation, 

North Carolina. Pleistocene: South Carolina, Florida. Recent: Cape Hatteras to Fernando de Noronha, Brazil, .and east to Bern1uda in 10 to 35 

fathoms. 

Subgenus DILUVARCA Woocking 

1925. Woodring, ,V. P., Miocene mollusks from Bowden, 

Jamaica: Carnegie Inst. Washington Pub. 366, p. 40= 

Seapharca of authors, not of Gray, Zool. Soc. London 

Proc., p. 198, 1847. 

Type: Area diluvii Lamarck. Miocene to Recent, 

Mediterranean Sea. 

The following is a description of Diluvarca: 

Shell heavy, medium-sized, moderately elongate, strongly 

inflated, inequilateral, equivalve, valves closed along ventral 

margin; umbos high and full; sculpture consisting of strong, 

narrow, flattened radial ribs separated by squarely channeled 

interspaces, ribs beaded by concentric threads; cardinal area 

relatively wide, on adult shells almost entire area occupied by 

ligament and bearing chevron-shaped ligament grooves diverging from under umbo at an obtuse angle; hinge uninterrupted 

but consisting of two series of teeth unequal in length; the 

shorter anterior series comprising teeth that are slightly oblique 

at anterior end and become vertical but not much reduced in 

size at posterior end; the longer posterior series comprising 

t-eeth that are strongly oblique at posterior end and become 

vertical and very small at anterior end; posterior muscle scar 

quadrangular, larger than the rounded anterior scar; margin of 

valve deeply fluted. 

Diluvarca (Diluvarca) latidentata (Dall) 

Plate V, Figure 7 

1898. Seapharea (Scapharea) latidentata Dall, Wagner Free lnst. 

Sci. Trans., vol. 3, pt. 4, p. 638, pl. 32, fig. 15. 

1915. Seapharea latidentata Dall> U. S. Nat. Mus. Bull. 90, p. 

121, pl. 25, fig. 2 (part). 

1917. Area latidentata Dall. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 33, pl. 7, figs. 17-20. 

Dall described tllis species in 1898 as follows: 

Shell small, ovate, moderately convex, with low, quite anterior, mesially sulcate, prosocoelous beaks; left valve with 

about 30 rounded, radiating, undivided ribs, separated by 

slightly wider interspaces and crossed by numerous smaller 

concentric ridges which become beadlike on the ribs and vary 

in prominence in different specimens; base evenly arcuate, 

ends rounded; cardinal area narrow, impressed, smooth, with 

one or two grooves behind the beaks but none elsewhere; 

valves slightly twisted, so that the basal margin is not in a 

single plane; line of teeth interrupted a little behind the beaks, 

the anterior series having the anterior and posterior teeth 

larger and the intervening teeth thinner and more closely 

u Annals and Mag. Nat. Hist., 2d ser., vol. 19, p. 371, 1857. 

u ·wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 618, 1898. 
PRIONODESMACEA AND ANOMALODESMACEA 29 

adjacent, all nearly vertical; posterior teeth vertical, shorter, 

the series longer, the teeth smallest proximally and regularly 

increasing in size toward the distal end of the series, equidistant 

and regular; inner margin of the valve deeply fluted. Longitude 18, height 11, diameter 9 millimeters. 

This little shell looks a good deal like the young of Anadara 

aresta Dall but has the beaks less central, less prominent, and 

distinctly impressed mesially, giving a somewhat bilobed aspect 

to the very young. 

Type: U.S. Nat. 1r1us. No. 107720. 

Type locality: No. 2564, McClelland farm, 1 mile 

below Baileys Ferry, Calhoun County, Fla. · 

There is no Diluvarca reported frm.a the .Alum Bluff 

which shares with lat'identata the evenly arcuate base 

and the narrow, well-elevated radials separated from 

one another by interspaces of approximately t.he~r 

own width. 

Occurrence: Chipola formation, localities 10609r, 

7893r, 2212P, 2214r, 2213c, 2564r, 3419r. 

Diluvarca (Diluvarca) mikkula Gardner, n. sp. 

Plate V, Figures 8-9 

Shell very small, slightly inequivalved, transversely elongated, subrectangular. Umbones rather 

full, moderately elevated, the apices turned inward 

and slightly forward and placed at some little distance 

in front of the median vertical. Length of dorsal 

margin approximating but not equaling the maximum 

latitude of the shelL Anterior margin intercepting 

the dorsal at nearly a right angle, expanding slightly 

in front of the dorsal margin. Base line broadly and 

feebly constricted at the terminus of the shallow 

umbonal depression, expanding posteriorly. Posteroventral margin slightly produced and rounded. Posterior lateral n1argin oblique, intercepting the dorsal 

margin at an acute angle. Un1bonal depression 

shallow but distinct. Posterior keel obscurely defined 

toward the un1bones, obsolete away from the umbones. 

Radial sculpture of low, narrow bands widening 

laterally, especially upon the posterior slope, 23 in 

number, separated by angular, interradial channels of 

approxin1ately their own width. Concentric sculpture restricted to exceedingly fine laminae, visible for 

the most part only in the interspaces on the posterior 

half of the shell but in some specimens overriding the 

radials frmn the umbones to the postero-ventral 

margin. Margins crenate in harmony with the radial 

sculpture. Cardinal area narrow, produced posteriorly, expanding somewhat beneath the umbones. 

Area of ligament attachment rhomboidal, coincident 

anteriorly with the cardinal area but more restricted 

posteriorly; one or two grooves directed obliquely 

backward from the umbones, the more shallow of the 

two defining the posterior limit of the ligament. Inner 

margin of hinge broadly and feebly arcuate. Hinge 

teeth very fine, especially beneath the umbones, 

less fine and more obliquely distal. Adductor scars 

867196 0-50-5 (142-A) 

obscure, placed well up toward the hinge. Anterior 

scar roundish, smaller and more regular in outJine 

than the posterior. 

Dimensions: Altitude, 3.5 millimeters; latitude, 

G.O millimeters; diameter, 3.2 millimeters. 

Type: U. S. Nat. Mns. No. 352305. 

Type locality: No. 2211, Alum Bluff (lower bed), 

Liberty County, Fla. 

This sn1all and prolific bivalve has been considered 

to he the young of D,iluvarca hypomela (Dali), but it is 

much heavier than hypomela of the same size and more 

nearly rectangular. The umbonal depression is less 

pronounced, and the radials are broader and flatter 

and normally less than 30 in number, whereas those 

of hypomela commonly exceed 40. 

Occurrence: Chipola formation, localities 2213a, 

2564a. 3419a, 221P, 7183c, 10660r. 

Diluvarca (Diluvarca) hypomela (Dall) 

Plate V, Figure 12 

1898. Scapharca (Scapharca) hypomela Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 637, pl. 33, fig. 1. 

1913. ?Scapharca hypomela Dall, U. S. Nat. Mus. Bull. 90, 

p. 121, pl. 17, fig. 7, pl. 21, figs. 17, 18. 

1917. Area hypomela Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 34, pl. 7, figs. 22-25. 

Dall described this species as follows: 

Shell of moderate size, long, inflated, with rather low, mesially 

compressed, prosogyrate beaks; left valve with about 43 deeply 

channeled, fiat-topped ribs with fine, regular, concentric 

beading, except on the posterior slope, where the ribs are lower, 

flatter, and obsoletely channeled; near the margin some of the 

ribs have a second set of finer grooves; hinge line straight, 

anterior end descending vertically, then obliquely rounded into 

the base, which is nearly parallel with the hinge line; the posterior end descends more obliquely and the basal angle is 

prolonged a little and rounded; the interspaces between the 

ribs in both valves are very narrow, and on the right valve the 

beading is less conspicuous; the cardinal area is somewhat 

concave, flattish, with three or four concentric grooves in 

lozenge form; teeth of the hinge similar, numerous, not interrupted, short, vertical, the distal teeth a little longer and 

more oblique; margin of the valves fluted, the right valve 

slightly smaller than the other. Longitude 50, altitude 25, 

diameter 20 millimeters. 

This species has the appearance of being the Oligocene 

ancestor of the Miocene A. lienosa, from which it differs by 

its smaller size, closer and rather narrower ribbing. 

Type: U. S. Nat. Mus. No. 114800. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

The Ballast Point individuals are smaller, heavier, 

and more inflated than those from the Chipola and 

present differences of at least subspccific value. The 

casts from Sopchoppy indicate a more evenly inflated 

shell and an earlier and more constant bifurcation 

of the radials. The rather ornate sculpture of the 

adult hypomela together with its transversely elongated 

outline is sufficient to separate it from the coexistent 

members of the genus. The Oak Grove Diluvarca 
30 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

dodona is higher relatively and has higher, more inflated umbones, a less obtuse rostrum, and more finely 

divided radials. Area henikeni Maury from the 

Cercado and Gurabo formations of the Dominican 

Republic is intermediate in outline between Diluvarca 

hypomela Dall and D. dodona from the Oak Grove. 

The details of the sculpture, however, are more simple 

than in either of the Alum Bluff species. Diluvarca 

acompsa from the Chipola suggests an adolescent 

hypomela but is more uniform in altitude in the 

anterior and posterior portions of the shell, the base 

line running approximately parallel to the dorsal 

margin .throughout its extent. The very young hypomela may be separated from D. mikkula by their 

thinner shells, more irregular, somewhat bilobate 

outline, and more numerous radials. 

Occurrence: Chipola formation, localities 10609P, 

7893r, 2212P, 7257r, 2213°, 2564P, 3419°7 ?7468r. 

Oak Grove formation, locality 5630 r. Shoal River 

formation, locality 10603~>. 

Diluvarca (Diluvarca) acompsa (Dall) 

Plate V, Figure 11 

1898. Scapharca (Scapharca) acompsa Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 648, pl. 33, fig. 15. 

1917. Area acompsa Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 34, pl. 7, fig. 21. 

Dall described this species in 1898 as follows: 

Shell rectangular, elongate, rather compressed, with low 

prosocoelous beaks, situated at about the anterior fourth of 

the whole length; right valve with about 36 flattened radial 

ribs, with much narrower interspaces; the anterior (22) ribs are 

mesially divided by a sharp groove and feebly rippled above; 

the posterior ribs are flat, smooth, and increase in width backward; the anterior end of the shell is evenly rounded, the base 

straight and parallel with the hinge line, the posterior end 

wider, a little produced below and with a conspicuous angle 

above; cardinal area long, very narrow, with one or two grooves, 

and bordered behind with an elevated margin; hinge line 

straight, long, with numerous small, uninterrupted teeth, 

very short mesially, longer and somewhat more oblique distally; inner margin of the valves fluted, shell thin and delicate. 

Longitude 20, altitude 10.5, semidiameter 4.5 millimeters. 

Only two right valves of this little species have been examined. 

It resembles the young of A. hypomela but is immediately 

distinguishable by its more compressed and rectangular form 

and smooth, flat posterior ribs. 

Type: U. S. Nat. Mus. No. 114794. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

In the young hypomela, especially those too young 

to have developed the sculptural details, the posterior 

portion of the shell is decidedly broader than the 

anterior, so that the base line is not parallel to the 

hinge as in acompsa but oblique to it. 

No further valves referable to this species have been 

found. 

Occurrence: Chipola formation, localities 2212r, 

2213r. 

Diluvarca (Diluvarca) dodona (Dall) 

Plate V, Figures 14-15a 

1898. Scapharca (Scapharea) dodona Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 640, pl. 31, figs. 1, 8, Sa. 

1917. Area dodona Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 37, pl. 8, figs. 6-10. 

Dall described this species in 1898 as follows: 

Shell small, solid, inequilateral, inflated, and rounded in 

front, pDinted and attenuated behind; with mesially impressed, 

prosocoelous beaks; left valve with 36 squarish radial ribs, each 

with a deep central groove longitudinally, the portions on each 

side with a shallower longitudinal sulcus, so that each rib, 

except in young shells, is composed of four threads set in two 

·pairs; the ribs separated from each other by channeled interspaces about half as wide as the ribs; concentrie sculpture of 

numerous rather close set, regular, blunt, elevated lines, which 

appear on the riblets as fine undulations; beaks at the anterior 

third; cardinal area, with a raised margin, lozenge-shaped, rather 

wide, slightly narrower behind tae beaks, with about four 

rather wavy sets of concentric grooves; hinge line short, solid, 

the teeth not interrupted, larger distally, the most anterior 

tending to break up into granulations, about 50 in all, subvertical, shorter in the middle of the hinge; margins of the valve 

deeply fluted; right valve with wider interspaces and narrower, 

often tripartite, ribs. Longitude 40, altitude 28, diameter 30 

millimeters. 

This fine shell has a neat and elegant surface sculpture, and 

is one of several which the Oak Grove marl contains and which 

appear to be new. 

Type: U. S. Nat. Mus. No. 107385. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

Diluvarca dodona is the nwst ornate of all the 

Diluvarcas reported from the Alum Bluff. Diluva.rco., 

hypomela. fronT the Chipola presents the same general 

type of sculpture but is relatively lower and more 

elongated transversely and the ribs are more numerous 

and cut by only a single longitudinal sulcus. 

The species is prolific and widely distributed 

throughout the Oak Grove. 

Occurrence: Oak Grove sand, localities 2646Pr, 

5632°7 563JP, 5630P, 5633P, 7054c. 

Diluvarca (Diluvarca) staminata (Dall) 

Plate V, Figure 13 

1898. Scapharea (Scapharca) staminata Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 641, pl. 31, fig. 11 

(fig. 13 excluded). 

1917. Area staminata Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 39 (part), pl. 9, figs. 4, 5 (fig. 6 

excluded). 

Dall described this species in 1898 as follows: 

Shell of moderate size, plump, rhombic, with well-elevated 

hardly sulcate, slightly prosocoelous beaks, situated in the 

anterior third of the length; left valve with 28 or 29 radial ribs, 

the posterior of which are smooth and almost rounded; those 

on the middle of the valve are squarish, with wider channeled 

interspaces, and rippled or furnished with transverse nodulation 

above, which grows stronger and more crowded anteriorly; 

the ribs are not. sulcate or dichotomous, and hardly differ on 

the two valves; hinge line straight, rather long, and with conspicuous angles at the ends; anterior end of the valve rounded, 
PRIONODESMACEA AND ANOMALODESMACEA 31 

base nearly parallel with the hinge line, posterior end somewhat produced; beaks narrow, cardinal area with from three 

to five sets of lozenge-shaped groovings; hinge strong, the teeth 

in two adjacen\ series, somewhat oblique, smaller mesially, at 

the anterior end of the hinge sometimes more or less broken 

into granules; inner margin of the valves fluted, interior radially 

striate. Longitude of a large valve 47, altitude 37 millimeters, 

longitude of figured shell 39, altitude 30, diameter 28 millimeters. 

This species differs from A. santarosana, which occurs in the 

same beds, by its more rhombic form, proportionately longer 

hinge line, and unsulcate ribs. It is also a larger and less 

elegantly sculptured shell. A. staminea Say1 of which staminata 

may prove to be an Oligocene race, has a proportionately 

longer hinge line, is more sharply truncate behind and more 

obliquely rounded in front, the beaks are less elevated and 

wider, the ribs anteriorly are only sparsely and feebly nodular, 

while the aspect of the whole shell is less elegant. 

Type: U.S. Nat. Mus. No. 149025. 

Type locality: No. 2211, Alum Bluff Gower bed), 

Liberty County, Fla. 

Dil'ltvarca staminata is another of the surprisingly 

numerous species peculiar to the coarse sands of 

Alum Bluff. Though contemporaneous forms, Diluvarca staminata and Diluvarca santarosana geraetera 

seem to be mutually exclusive, as the one is known 

only from Alum Bluff, the other from the Chipola. 

The specimens from Escambia County, Ala., tentatively referred to D. staminata are more closely allied 

to D. santarm:;ana geraetera. Diluvarca chiriq_uiensis 

(Gabb) from the Thomonde formation of Haiti differs 

from all of the Alum Bluff members of the staminata 

group in the equal valves, the more obtuse posterior 

keel, the much broa.der, more closely scored cardinal 

a.rea, and consequently more widely separated umbones. 

By a curious error an individual of a quite distinct 

species-Diluvarca waltonia Gardner-from Walton 

County was figured by Dall. 

Occurrence: Chipola formation, localities 2211 c, 

7183°, 10660°, ? 7468P. 

Dituvarca (Diluvarca) santarosana (Dall) 

Plate VI, Figures 1-2 

1898. Scapharca (Scapharca) santarosana Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 641, pl. 31, figs. 2, 10. 

1917. Area santarosana Dall. Sheldon, Palaeontographica 

Americana, vol. 1, No. 1, p. 38, pl. 9, figs. 1-3. 

Dall described this species in 1898 as follows: 

Shell small, short, plump, rostrate, with moderately elevated, 

mesially sulcate prosocoelous beaks; left valve with 30 elevated, squarish, radial ribs, separated by slightly narrower 

channeled interspaces; the ribs on the posterior slope are low, 

smaller, and nearly smooth; those on the middle of the shell 

have mostly near the margin a shallow mesial sulcus; in those 

still more anterior the sulcus is deeper and wider, dividing each 

rib over most of its length into two more or less rounded riblets; concentric sculpture of regularly spaced elevated lines, 

which on the ribs appear as prominent ripples; right valve 

having the ribs narrower and less strongly sculptured, and the 

sulci less distinct; cardinal area short, with about three concentric grooves; beaks within the anterior fourth; hinge line 

!:ihort, with about 57 rather irregular, closely adjacent, nearly 

vertical teeth, longer and more oblique distally; margins 

strongly fluted; base flexuous, posterior end narrow, pointed, 

without any marked angle at the end of the hinge line. Longitude 36.5, altitude 28, diameter 28 millimeters. 

This species is most nearly related to A. staminata Dall, 

from which it can be distingui8hed especially by its lower beaks, 

more oblique posterior slope, more flexuous base, and attenuated posterior end. 

Type: U.S. Nat. Mus. No. 107386. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County (formerly Santa Rosa County), Fla. 

The Chipola specimens have ~een segregated under 

the subspecies geraetfira because of their relatively 

higher altitude consequent upon the more elevated 

and narrower umbones. The two forms occupy about 

the same relative position in the faunas which they 

characterize. 

The species that occurs abundantly in the vicinity 

of Bainbridge, Decatur County, Ga., is for the most 

part the typicalsantarosana, though there is a tendency 

toward variation along the lines of geraetera. Apparently a second species or subspecies is present at 

this locality, though represented only by immature 

forms. These individuals differ from the young 

santarosana in their much lower, broader outline. 

The ornamentation and cardinal area, however, 

offer no distinguishing characters, and the forms in 

question are left nameless for the time being. 

Occurrence: Oak Grove sand, localities 3386°, 

3385°, 7148°, 3396°, 2646a, 5632P, 5631r, 5630P, 5633r, 

7054P, 9961r, 7055P, 10659a. Shoal River formation, 

locality ?5192r. 

Diluvarca (Diluvarca) santarosana geraetera Gardner, n. 

subsp. 

Plate VII, Figures 1-2 

1917. ''Area staminata" Sheldon, Palaeontographice Americana, 

vol. 1, No. 1, pl. 9, fig. 6. (Figs. 4 and 5 excluded.) 

Not Scapharca (Scapharca) staminata Dall, 1898. 

Shell of moderate dimensions, :heavy, the left valve 

a little larger than the right. Trigonal in the exterior 

view, the interior, excluding the cardinal area and the 

prominent umbones, subrhomboidal. Umbones rather 

narrow but full, conspicuously elevated, incurved and 

prosogyrate, the apices within the anterior third. 

Dorsal margin straight, a little shorter than the 

greatest width of the shell. Anterior margin slightly 

constricted at the hinge, broadly and feebly rounded, 

merging smoothly into the base line, which is somewhat compressed in the adults directly in front of 

the posterior keel. Rostrum subacute and well 

defined from the umbones to the ventral margin. 

Posterior area obliquely flattened, the posterior margin 

intercepting the dorsal at an angle of more than 90°. 

Ribs of right valve normally 31 or 32, including the 10 

or 11 upon the posterior slope; costals on anterior 

part of shell corrugated by the incrementals and 

~sially sulcate, the groove being deepest, tho 

wrinkles heaviest, and the spacing widest along the 
32 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

curve from the anterior to the medial portion of the 

shell; depression in front of posterior keel emphasized 

by the disappearance of all ornamentation upon the 

costae; posterior ribs relatively narrow, rounded, and 

feebly corrugated. One more rib in left valve than in 

right; ribs of left valve corrugated or nodose and 

feebly sulcate upon the antero-medial arch, narrower 

and less closely spaced posteriorly than upon the 

medial portion of the shell. Inner margins flu ted in 

harmony with the external sculpture. Cardinal area 

broad, rudely kite-shaped in the double valves, scored 

with sinuous ligament grooves, which are rudely concentric and tend to arch up toward the umbones. 

Hinge very narrow, feebly arcuate along its inner 

margin, finely serrate; the teeth not far from 50, 

arranged in two series and tending to break up 

and become irregular at the extremities of each series. 

Muscle impressions rather large, well defined, the 

posterior larger, less regular, and more remote from 

the hinge than the anterior and, in the adult, feebly 

buttressed. Pallial line running parallel and rather 

close to the outer margins. 

Dimensions: Altitude of right valve, 35.0 millimeters; left valve, 36.5 millimeters. Latitude of 

right valve, 37.5 millimeters; left valve, 39.0 millimeters; diameter, 37.0 millimeters. 

Cotypes: U.S. Nat. Mus. No. 352308. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

The subspecies geraetera differs from santarosana. 

s. s. in the narrower and more elevated umbones. 

This dimensional difference is so constant in the great 

majority of the specimens from Chipola River and 

appears so early in the shell that it is worthy to be 

recognized in the nomenclature. There are a nun1ber 

of young forms apparently unrepresented in the adult 

which differ from. the normal geraetera in the 1nore 

produced and angulated posterior keel. In the normal 

young of geraetera the base line is approximately 

parallel to the dorsal margin, whereas in the adult 

they converge slightly posteriorly. In the abnormal 

young forms mentioned, however, the base line is 

pulled down at the keel, so that it diverges from the 

dorsal margin and simulates in external aspect smne of 

the coexistent Cardium (Fragum). In the absence of 

adults these juveniles are included under geraetera. 

Occurrence: Chipola formatio:r1, localities 10609c, 

7893P, 2212c, 7257P, 2213a, 2564a, 3419c, 9994P, 

7151 c, 3704P, ~7468P, 5613c, 5629a. 

Diluvarca (Diluvarca) waltonia Gardner, n. sp. 

Plate VI, Figures 3-6 

1898. Scapharca (Scapharca) starninata Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, pl. 31, fig. 13 (description 

excluded). 

1898. Scapharca (Scapharca) starninea Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 642 (part). 

Not Area starninea Say, American marine conchology.pl. 

36, fig. 2 and text, 1832. 

1898. Scapharca (Anadara) clisea Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 657 (part). 

Shell rather large, heavy; the left valve a little the 

larger of the two, ovate-trigonal in outline when 

viewed from the exterior. L"mbones broad and well 

rounded, elevated high above the hinge line, incurved 

and feebly prosogyrate, set a little in advance of the 

median vertical. Anterior area rounding s1noothly 

into the medial. Posterior area obliquely flattened 

and delimited by a subacute keel \rhich persists from 

the umbones to the outer margin. Dorsal margin 

approximately the greatest width of the shell but a 

little less produced posteriorly. Anterior lateral 

margin approximately at right angles to the dorsal for 

a short distance then merging smoothly into the~upcurved base. Ventral margin nearly 'parallel to the 

dorsal, though inclined to diverge E~ightly behinJ. 

Postero-ventral margin producE-J bey·~nd the dorsal, 

the posterior lateral margin consequently oblique. 

Right and left valve discrepantly sculptured, each,. 

however, with approxin1ately 30 ribs; anterior eostals 

of right valve corrugated or obtusely nodulated by 

the modified incremental sculpture, the costal 

ornamentation becoming reduced on the medinl portion of the shell and nearly obsolete on the half 

dozen ribs direetly in front of the keel; the half 

dozen ribs directly behind the keel also simple and 

more rounded than on any other portion of the shell; 

the four or five radials nearest the posterior margin 

relatively very narrow and finely nodulated; all the 

costals upon the left valve nodose in the young forms, 

those upon the posterior area, however, becmning 

simple in the adults; interradials relatively wider and 

more angular in the right valve than in the left. 

Inner margin sharply fluted in harmony with the 

external sculpture. Cardinal area wide in the adults, 

rising quite steeply from the hinge to the umbones, 

little or not at all concave, rhomboidal in the double 

valves, scored with irregular grooves, con1monly discontinuous but arranged roughly in concentric rhonlboids, about eight in the adult. Hinge narrow but 

rather heavy, reinforced distally, v:ery finely and 

closely serrate. Teeth arranged in two series which 

meet with a barely perceptible interruption directly 

behind the u1nbonefl; anterior series including ahout 

20 denticles, the posterior from 25 to 30; teeth in the 

medial portion of the hinge norn1al to the margin, 

those near the distal extren1ities more oblique and 

irregular. Adductor scars very large and distinct, the 

anterior n1ore regular in outline and placed nearer to 

the dorsal n1argin than the posterior. Pallid line 

distinct, running parallel and quite close to the ventral 

margm. 

Dimensions: Altitude, 32.5 millin1eters; latitude, 

33.0 n1illimeters; diameter, 36.0 millimeters. 

Type: U. S. Nat. Mus. No. 352306; figured specimen, U. S. Nat. Mus. No. 113827. 
PRIONODESMACEA AND ANOMALODESMACEA 33 

Type locality: No. 3856, 6 n1iles west-northwest of 

Mossyhead, Walton County, Fla. 

Diluvarca waltonia is the close analog of Diluvarca 

santarosana from the Oak Grove and its Chipola subspecies geraetera. It is the heaviest of the three forms 

and relatively the highest. The un1bones are more 

tumid than those in either of the older forn1s, the 

depression in front of the posterior keel is obscure or 

obsolete, and the base line is consequently straighter. 

The cardinal area is higher as a rule than that of the 

Oak Grove species, and the hinge is less delicate. 

The only differences in sculpture are those concomitant 

with the thicker, ruder shell of waltonia. Though 

the adults of these forms can be readily separated, 

many of the immature individuals are indistinguishable. 

Diluvarca clisea (Dall), to which the specimens from 

Walton County have occasionally been referred, is a 

larger, more oblique form with the postero-ventral 

extremity of the shell pulled downward and backward. The two valves of clisea are similarly sculptured, .and the number of ribs in some specimens runs 

as low as 26. Diluvarca staminata is a broader 

species with a higher, n1ore concave, and more nearly 

syn1metrical cardinal area. Diluvarca staminea Say 

is n1uch closer to D. 1.ca.ltonia than either clisea or 

staminata and its possible descendant, a hypothesis 

strengthened by the closer similarity of the Shoal 

River forms to the specimens from the Calvert than 

to those from the St. 11arys. The 11aryland species 

offers a wide range of variation in outline, but those 

individuals in which the relative altitude is as great as 

in waltonia develop a higher cardinal area. The average number of ribs is lo-wer in the Maryland forn1, and 

those directly in front of the posterior keel are nornlally bisulcate or trisulcate, a character not observed 

in any waltonia. 

Occurrence: Shoal River formation, localities 3856Pr, 

3732P, 3742a, 3731 c, 10658P, 5080r, 5184P, 5195r, 

?5079a, 10661 c, .5193r, 5194r, 3733P, 2238r, 9958P, 3748c, 

3747r, 7264r, 99G0P, '?10603c, 5618c, m959c. 

Diluvarca (Diluvarca) strebla Gardner, n. sp. 

Plate VIII, Figures 1-2 

Shell of n1oderate dimensions, rather thick, the left 

valve a little the larger, transversely elongated, 

broadly and quite strongly inflated from the umbones 

to the ventral margin, somewhat constricted toward 

the posterior extremity, especially in the right valve, 

thus giving to the shell a slightly warped appearance. 

embones broad, very full, incurved and prosogyrate, 

the apices cmnpressed and feebly sulcated medially, 

placed a little in front of the median vertical and 

rather close together. Posterior keel obsolete, the 

posterior slope of the umbones more sharply rounded, 

however, than the anterior. Dorsal margin straight, 

a little more than three-fourths as long as the maximum 

width of the shell. Anterior lateral margin retreating 

from the dorsal, which it intercepts approximately 

at right angles, and merging into the upcurved base. 

V antral margin expanded anteriorly so that the greatest altitude is in plumb with the umbones, constricted 

posteriorly in the adults but not in the young. Posterior extremity in the adults narrow and quite 

sharply rounded, the lateral margin intercepting the 

dorsal at an angle not far from 135°. Sculpture very 

similar in the two valves, the costals of the left valve 

being a little n1ore elevated and more wrinkled by the 

concentric sculpture than those of the right. Radials 

simple, the same in number in the two valves-approximately 34-narrower and more closely spaced 

medially and less modified by the incremental sculpture than toward the extremities. Concentric lamination very fine, close, and even, corrugating the 

anterior costals, especially in the younger forn1s, but 

on the posterior portion of the shell almost obsolete, 

except in the channels. Interradials a little narrower 

as a rule than the radials, though commonly a trifle 

wider upon the medial ventral portion of the adult 

left valve. Inner margins fluted in harmony with 

the external sculpture. Cardinal area rather narrow, 

concave, rhomboidal, the portion behind the un1bones 

n1ore produced and attenuated than that in front of 

it. Ligament grooves in the double valves arranged 

in about half a dozen more or less regular, concentric 

rhomboids. Hinge narrow but rather heavy, reinforeed distally, very finely and closely serrate. Teeth 

arranged in two series, their interior extremities adjoining one another with a barely perceptible break, 

the number in the anterior series running as high as 

35, in the posterior series up to 45; serrations in the 

medial portion of the hinge very fine, close, and at 

right angles to the margin, coarser and somewhat 

oblique toward the outer extremities. Adductor scars 

large and prominent, the anterior a little more rounded, 

not quite so large and placed a little higher than the 

posterior, which is rudely quadrate in outline and 

elongated parallel to the posterior margin of the 

cardinal area. Pallial line distinct, parallel to the 

outer margin and not far distant !'rom it. 

Dimensions: Altitude, 27.0 millimeters; latitude, 

41.0 millimeters; diameter, 26.0 millimeters. 

Type: U.S. Nat. Mus. No. 352309. 

Type locality: No. 3856, 6 miles west-northwest of 

Mossyhead, Walton County, Fla. 

No similar species has been collected from the Alum 

Bluff group. The upper bed at Alum Bluff, the Choctawhatchee n1arl, contains a possible descendant-

" Scapharca (Anadara)" aresta Dall. The younger 

form is smaller, a little lower relatively, and less 

tumid, but it exhibits the same peculiarities of outline 

and the same type of sculpture. The closest affinities 

of strebla, however, are with a probably synchronous 

species of the Diluvarca section, Diluvarca actinophora 
34 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

(Dall), from Monkey Hill. The Floridian form differs 

in being a little more inflated than the Panaman and 

more compressed posteriorly. 

Occurrence: Shoal River formation, localities 3856a, 

3742P, 3731 c, 5184r, ~9960r, 10603P, 5618P, 10612P, 

Section CUNEARCA Dall 

1898. Cunearca Dall, Wagner Free Inst. Sci. Trans., vol. 3, pt. 

4, p. 618. 

Type: Area incongrua Say. (Recent on the east 

coast from Hatteras to the West Indies.) 

Dall describes this section as follows: 

Thin, trigonal, inflated, with erect beaks; the cardinal area 

short,, amphidetic, equilateral, set off by deep grooves from the 

rest of the sculpture, smooth or transversely striated, without 

furrows; hinge teeth divisible into two series, smaller proximally, 

larger and more oblique distally, often more or less A-shaped; 

the right valve smaller; sculpture of the two valves obviously 

discrepant; the epidermis smooth or not pilos8. 

Diluvarca (Cunearca) initiator Dall 

Pia te V, Figure 10 

1898. Scapharca (Cunearca) initiator Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 634, pl. 32, fig. 11. 

1917. Area initiator Dall. Sheldon, Palaeontographica Americana, vol. 1, No. 1, p. 56, (?)pl. 13, figs .. 7-9. 

Dall described this species in 1898 as follows: 

Shell small, solid, oblique, with prosogyrate beaks, somewhat 

impressed mesially near the apices of the valves; right valve 

ovate-rhombic with 20 strong, rounded, nodulous, radial ribs, 

separated by wider interspaces; left valve decidedly smaller, 

with the ribs smooth, squarish, and without nodules, except a 

few on some of the shorter anterior ribs; cardinal area wider in 

front of the beaks, narrower behind them; margins of the valves 

internally fluted; hinge line short, with about 22 subequal 

vertical teeth. Longitude (of left valve) 5, altitude 4. 7, 

diameter 5 millimeters. 

This little shell was at first thought to be the young of a larger 

species, but nothing allied to it of a larger size has turned up at 

any locality in the formation, while its solidity gives it a mature 

appearance. The cardinal area differs in form from any of the 

known species in the adult state. 

Type: U.S. Nat. Mus. No. 107717. 

Type locality: No. 2564, McClelland farm, 1 mile 

below Baileys Ferry, Calhoun County, Fla. 

This small form suggests the young of Diluvarca 

santarosana geraetera Gardner, n. subsp., though it 

is heavier and more nearly equilateral; the sculpture 

is much more discrepant in the two valves, the radials 

are normally only 20 or 21 instead of 30 as in santarosana, and those of the right valve are coarser and n1ore 

nodose. Diluvarca cardioides, from the Oak Grove, is 

a very close analog of initiator, but it is a little larger 

and relatively broader and less globose. The number 

of ribs is approximately the same in both species, 

from 20 to 22, and may in both run up to 25, but those 

of initiator are not so broad as those of cardioides. 

The relative abundance of the two forms is about 

the same. Neither species is uncommon at the 

horizon which it characterizes. 

Diluvarca initiator (Dall) suggests a miniature 

Dil·uvarca cor-cupidonis (Maury) from the Thomonde 

of Haiti and the Cercado of the Dominican Republic. 

TheW est Indian shell is larger and coarser, with more 

inflated umbones. 

Occurrence: Chipola formation, localities 2213!l, 

2564P, 341W, 715F, 7183r. 

~iiss Sheldon reports and figures the specie5 from 

the Oligocene of Sour Lake, Tex. 

Diluvarca (Cunearca) cardioides Gardner, n. sp. 

Plate VI, Figures 7-10 

Shell small, solid, inequivalve, inequilateral, cordate-trigonal when viewed from the exterior, the interior rudely quadrate. Umbones well rounded, 

prominently elevated medially, sulcate only toward 

the apices, which are incurved, prosogyrate, placed a 

little in front of the median vertical and at a moderate 

distance from one another. Anterior area rounding 

smoothly into the medial, the posterior obliquely 

flattened and defined in the left valve by an obtuse 

keel, which in the right valve is obscure or obsolete. 

Dorsal margin straight, not quite equaling the maximum width of the shell. Anterior margin very feebly 

expanded, merging smoothly into the upcurved base. 

Ventral margin diverging slightly front the dorsal 

toward the posterior extremity. Postero-ventra] margin obtusely angulated. Posterior lateral margin 

oblique, intercepting the dorsal at an angle of a little 

more than 90°. Sculpture markedly discrepant in the 

two valves; ribs approximately 21 in number in each. 

the 7 or 8 anterior ribs of the right valve and the f• 

posterior feebly nodose, the 8 or 9 intermediate costals 

smooth and flattened upon their summits and separated by intercostal channels of approximately their 

own width; radials upon the anterior and medial portions of the left valve heavy, obtusely nodose, separated by deep and narrow intercostal channels; radial 

outlining the posterior keel the broadest upon the 

valve, nodulated in the young, smooth in the fully 

adult; posterior ribs relatively narrow and widely 

separated, feebly nodose in the young, nearly smooth 

in the adult. Inner margins crenate in harmony 

with the external sculpture, the flutings persisting into 

the interior of the shell almost to the umbones. 

Cardinal area rhombic in the double valves, narrower 

and more produced behind the u1nbones than in front 

of them. Area of ligament attachment more symmetric than the cardinal area, for the most part 

opisthodetic and outlined by two deep grooves diverging from a point a little behind the apices of the 

umbones. Hinge narrow, the ventral margin feebly 

arcuate; hinge teeth about 30, very fine and approximately vertical medially, a little coarser distally and 

somewhat oblique. Anterior adductor rather small, 

roundish, placed just within the extremity of the 

hinge. Posterior adductor larger, more irregular in 
PRIONODESMACEA AND ANOMALODESMACEA 35 

outline, less dorsal in position than the anterior. 

Pallial line simple, parallel to the outer ·margin, and 

at some little distance from it. 

Dimensions: Right valve, altitude, 5.0 millimeters; 

latitude, 5.8 millimeters; semidian1eter, 2.0 millimeters" 

Left valve of another individual, altitude, 7.7 millimeters; latitude, 9.0 millimeters; semidiameter, 3.6 

millimeters. 

Cotypes: U.S. Nat. Mus. No. 352307. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

This small species, which suggests Cardium (Fragum) 

in its general appearance, is the analog of the Chipola 

D. initiator. The Oak Grove form is the larger of the 

two, is less globose, and is relatively broader. The 

costals number approximately the same in the two 

species, but those of D. cardioides are a little heavier. 

In both species there is considerable variation in the 

number of ribs, which may be as high as 25. 

Occurrence: Oak Grove sand, localitieii! 2646P, 

5632P, ~ 5631 r, 7054r, 996] r. 

Genus GLYCYMERIS Da. Costa 

1778. Glycymeris Da Costa, British conchology, p. 168. 

Type: Glycymeris orbicularis Da Costa= Area glycymeris Linnaeus. (Recent off the British Isles and the 

coast of Europe.) / 

Shell heavy, equivalve, equilateral or subequilateral, 

suborbicular. Beaks almost straight, only very 

slightly incurved. Hinge margin arcuate, set with 

two series of strong transverse teeth which are progressively obliterated during growth by the subsidence 

of the cardinal area. Exterior surface of valves 

concentrically or radially striate. 11argins crenulate 

within. Adductor scars subequal. Pallial line simple 

or very slightly sinuous. 

The genus originated in the Cretaceous, culminated 

in the Miocene, and is represented to-day by about 

80 species, widely distributed in the shallower waters 

of the warm and temperate seas. 

Glycymeris is represented in the Alum Bluff group 

by few species, but by a wealth of individuals. Four 

out of five species and subspecies are referable to the 

group of Glycymeris subovata Say, so prominent in the 

later Tertiary. Each horizon has its characteristic 

member of the group, and in the Oak Grove there is 

also a subspecific form developed. The diagnostic 

members of the group, Glycymeris drymanos and its 

subspecies grapta in the Oak Grove and G. waltonensis in the Shoal River, are exceedingly abundant. 

The true G. subovata, which occurs in the Chipola and 

rarely in the Shoal River, is much less prolific. It 

is also interesting to note the backward extension of 

the range of G. pectinata Gmelin, which is so common in the later Tertiary and so abundant in the shallow waters of the Recent seas from Cape Fear south 

through theW est Indies. Another species, Glycymeris 

americana De France, which is prominent in the 

Recent faunas of the east coast, is possibly present 

in the Shoal River. If the worn valve from Whites 

Creek is not identical with the Recent form it is certainly a close forerunner. 

Radial sculpture of impressed sulci; altitude of adult exceeding 

20 millimeters: 

Radials persistent to the lateral margins and in the majority of the adults to the base; outline approximately 

symmetrical bilaterally: 

Shell not very heavy, relatively compressed; interradial spaces arched _______ Glycymeris subovata Say. 

Shell heavy, relatively inflated; interradial spaces 

fl.attened_Glycymeris drymanos Gardner, n. sp., s. 1. 

Secondary radial sulcations not developed. 

Glycymeris drymanos Gardner, n. sp., s. s. 

Secondary radial sulcations developed. 

Glycymeris drymanos grapta Gardner, n. subsp. 

Radials evanescent toward the lateral and in the adults 

toward the ventral margins; shell often obliquely produced posteriorly; interradial spaces flattened. 

Glycymeris waltonensis Gardner, n. sp. 

Rad1a1 sculpture of elevated costae; altitude of adult not exceeding 20 millimeters ________ Glycymeris pectinata Gmelin. 

Glycymeris subovata (Say) 

Plate VIII, Figures 3-8 

1824. Pectunculus subovatus Say, Acad. Nat. Sci. Philadelphia 

Jour., 1st ser., vol. 4, p. 140, pl. 10, fig. 4. 

1832. Pectunculus subovatus Say. Conrad, Fossil shells of the 

Tertiary formations of North America, p. 17, pl. 2, 

fig. 3. 

1845. Pectunculus subovatus Say. Conrad, Fossils of the 

medial Tertiary of the United States, p. 62, pl. 34, 

fig. 1. 

1858. Pectunculus subovatus Conrad. Emmons, North Carolina 

Geol. Survey Rept., p. 286, fig. 207. 

1863. Axinaea (Pectunculus) subovata Say. Conrad, Acad. 

Nat. Sci. Philadelphia Proc. for 1862, p. 581. 

1864. AxitttLea subovata (Say) Conrad. Meek, Check list of the 

invertebrate fossils of North America, Miocene: 

Smithsonian Misc. Coli., No. 183, p. 5. (Name only.) 

1898. Glycymeris subovata Say. Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 611. 

1904. Glycymeris subovata (Say). Glenn, Maryland Geol. 

Survey, Miocene, p. 394, pl. 107, figs. 3, 4. 

Say described this species in 1824 as follows: 

Longitudinally short ovate, with about 30 longitudinal 

impressed acute lines, the intervals a little convex. 

Shell increasing in width by a slightly curved line from the 

apex to beyond the middle; lateral curvatures equal; apices 

separate, small, central; intervening space with but little 

obliquity to the plane of the shell, with obsolete angulated 

lines; teeth forming a regularly and much arcuated series, 

which is rectilinearly truncated above so as to leave in that 

part a mere edentulous elevated line; within destitute of striae; 

margin with elevated angular lines; exterior surface with about 

thirty longitudinal, impressed, acute lines, the intervals a little 

convex. 

Length from the apex to the base 1-H· inches; breadth 1% 

inches nearly. 

Type locality: Maryland. 

Figured specimens: U. S. Nat. Mus. Nos. 325484 

(right valve; Suffolk, Va.), 325485 (left valve; 

Colerain Landing, N. C.) 

Glycymeris subovata Say differs narrowly in the outline and degree of convexity of the valves and rather 
36 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

widely in the character of the sculpture. The normal 

form is ornamented with 25 to 35 low, gently arched 

radials separated by deeply impressed linear grooves 

which are more closely approximated laterally and in 

the young shells. In the young, too, the ribs are 

much more strongly arcuate, but they broaden and 

flatten in the adults and, in senile individuals, evanesce 

toward the basal margin. The subspecies results from 

the tendency toward an asymmetric outline, the 

obliteration of the lateral sculpture, and the widening 

of the impressed grooves. 

The species is one of the most widely distributed 

and one of the most conspicuous of the east coast 

Tertiary molluscan fauna. 

The Chipola representatives are smaller than the 

later Tertiary individuals but differ in no other constant character from typical members of the species. 

Glycymeris dryrnanos is heavier and more inflated, 

with more flattened interradial areas and a somewhat 

coarser dental armature. Glycymeris waltonensis is 

also more inflated, as a rule, more or less produced 

posteriorly, much less strongly sulcated radially, 

especially toward the margins, and more compressed 

in the dorsal region. The Chipola representatives of 

the group do not begin to approximate in relative 

abundance either those of the Oak Grove or of the 

Shoal River. 

Occurrence: Chipola formation, localities 10609P, 

7893P, 2212P, 2213c, 2564c, 3419c, 9994r, ~7151r, 2211r. 

Shoal River formation, localities 9958r, 9959c. 

Outside occurrence: Miocene, Choctawhatcheemarl, 

Alum Bluff (upper bed), Calhoun County, Fla.; Jacksonville formation, Middleburg, Black Creek, Clay 

County, Fla.; Calvert formation, Maryland, Virginia; 

St. Marys formation, Virginia, North Carolina; Yorktown formation, Virginia, North Carolina; Duplin formation, North Carolina, Georgia. 

Glycymeris drymanos Gardner, n. sp. 

Plate IX, Figures 1-2 

Shell of moderate size for the genus, thick, heavy, 

rather tumid, subcircular to subovate in outline, in 

many specin1ens slightly produced obliquely. Posterior dorsal margin usually sloping a little n1ore 

steeply than the anterior. Lateral margins broad 

and merging gradually into the arcuate base. Dinbones subcentral or a little anterior, incurved, 

orthogyrate, acute at the tips, rounded, not very pron1-

inent. Normal external sculpture consisting of radiating sulci, 18 or 19 in nun1ber upon the medial 

portion of the types but ranging from 16 to 22 in 

other individuals, usually more closely spaced upon 

the posterior half of the shell than upon the anterior. 

Four additional sulci on each of the submargins of the 

types, but as many as 6 or 7 in other individuals, 

ail of them, both upon the disk and the margins, 

persistent as a rule to the outer edge. Interlinear 

spaces usually flat upon the disk, occasionally rounded, 

the interspaces upon the subn1argins in nwny specin1ens raised and comnwnly rather steeply inclined 

toward the dorsal margin. Concentric sculpture 

restricted to incrementals, n1ost prominent, as a rule, 

toward the ventral margin. Ligament area of nloderate size, rather high, approxin1ately symmetrical; 

sulci deep, 8 on each side in the type. Den tal arch 

high, interrupted in all but the very young by the 

submergence of the ligament area. Teeth strong, 12 

anterior and 12 posterior in the right valve, 14 anterior and 12 posterior in the left valve of the type; 

the number in the complete series about 15 to the side. 

Muscle scars conspicuous, the anterior slightly larger 

than the posterior, semi-elliptical or rounded conical 

in outline, the posterior rudely quadrilateral and feebly 

buttressed. Pallial line simple, distinct, rather distant 

from the margin. Interior of valve finely striat~ 

radially, especially just inside of the pallial line. Inner 

margins ornamented with a series of elevations, quadrate n1edially, trigonal distally. 

Din1ensions of right, valve: Altitude, 38.5 milliIneters; latitude, 38.5 millin1eters; diameter, 15.0 

millimeters. Di1nensions of left valve of another 

specimen: Altitude, 38.2 millin1eters; latitude, 37.5 

n1illimeters; diameter, 13.0 millimeters. 

Cotypes: U. S. Nat. Mus. No. 352310. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

The young are stocky little square-shouldered 

shells. 

Glycymeris drymanos Gardner, n. sp., is sn1aller than 

G. subo1-'ata Say with which it has been confused, 

relatively heavier and Inore inflated. The dorsal 

n1argins are not quite so wide, and the hinge area is 

consequently higher and the dental arch n1ore compressed. Then, too, the submargins are as a rule better differentiated than they are in G. subovata and 

the lineations upon the disk relatively Inore distant. 

The sulci are similar in character to those of suhovata, 

but the interradial spaces are for the n1ost part 

flattened and not rounded. G. waltonensis runs a 

little sn1aller and is not quite so heavy. Many 

specimens are obliquely produced posteriorly and are 

generally more or less cmnpressed in the dorsal region. 

The radial sulcation in the adult is more feeble than 

in G. drymanos, more or less obsolete toward the 

margins, and very commonly more distinct upon the 

posterior half of the shell than upon the anterior. 

The young and adolescent forms are, however, very 

difficult to separate, for the diagnostic features of 

G. waltonensis do not usually appear until the adult 

stage. Both Glycymeris drymanos and its subspecies 

grapta are exceedingly prolific at the type locality 

and its environs. 

Occurrence: Oak Grove sand, localities 2646Pr, 5632c, 

563F, 5630c, 5633c, 7054a, 2652P, 9961P, 7055c, ~3749c. 
PRIONODESMACEA AND ANOMALODESMACEA 37 

Glycyrneris dryrnanos grapta Gardner, n. subsp. 

Plate IX, Figures 3-4 

. Outline and general dimensions sin1ilar to those of 

G. drymarws, of moderate size, heavy, rather tumid, 

subcircular to subovate, the umbones subcentral, the 

dorsal margins more or less oblique, the posterior in 

many specimens slightly more produced than the anterior, the lateral margins broadly rounded or obscurely truncate, the base line arcuate. Primary 

radial sculpture similar to that of G. dryrrwmos s. s. 

and running through a similar series of variations, 16 

on the disk of the right valve of the type, 17 on 

the left in another individual, and 4 additional 

sulci on each of the subnwrgins of each valve. A 

further and exceedingly variable secondary sculpture 

deYeloped in the shape of fortuitous sulci, for the 

most part less deeply impressed than the primaries, 

rather more commonly developed upon the medial and 

anterior portions of the shell than ·upon the posterior; 

fnint secondary lineations suggesting those of G. 

amNicana developed near the base of the primaries, 

more con1monly with one or rarely two sulci running 

up from the basal margin halfway or more to the 

beaks. Submarginal ribs in many specimens strongly 

dissected. Characters of ligament and hinge areas and 

the interior similar to those of G. drymanos Gardner, 

n. sp.; the ligament area rather small and moderately 

high, with six or seven sulci diverging beneath the 

urn hones; the rather high dental arch with about a 

dozE'n teeth on either side; the anterior muscle scars 

:ounded, trigonal; the posterior smaller, rudely quadrate, and feebly buttressed; the interior of the disk 

faintly striated radially; the pallial line simple, distinct, the inner basal margin crenulated. 

Dimensions of right valve: Altitude, 37.0 millimeters; latitude, 37.6 millimeters; diameter, 13.0 

millimeters. Dimensions of left valve of another indiYidual: Altitude, 36.5 millimeters; latitude, 36.5 

millimeters; diameter, 13.5 millimeters. 

Cotypes: U.S. Nat. Mus. No. 352311. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

The secondary radial sculpture, the diagnostic character of the subspecies, doe:::; not develop until the 

forn1 is about half grown, so that the young can not 

be sepnratE'd from the young of G. drymanos s. s. 

Occurrence: Oak Grove sand, localities 2646Pr, 

5632r, 5630r, 5633r, 7054P. 

Glycyrneris waltonensis Gardner, n. sp. 

Plate IX, Figures 5-8 

Shell of modernte size for the group, moderately 

thick and heavy, and moderately inftnted. Outline 

suhcircular and approximately symmetric bilaterally 

in the young and adolescent, in n1any specimens 

quite strongly and obliquely produced posteriorly in 

~h71Yii 0-50-fi (142-A) 

the adults. Umbones rather low, rounded, acute at 

their apices, orthogyrate, and in the adults more or 

less anterior in position. Dorsal margins converging 

at an angle of 45° to 60°, the posterior margin generally more produced than the anterior. Anterior lateral margin -very broadly rounded or obscurely truncate. Posterior lateral margin obscurely differentiated, as a rule, very short, rounded or obtusely 

truncate, the dorsal margin usually produced beyond 

the median horizontal. Base line arcuate, more 

strongly and more abruptly upcurved in front than 

behind. External surface radially sulcate, the sulci 

linear and "'.'arying in number, -as a rule between 20 

and 30, lnclined to become obsolete toward the margins, both the lateral and the ventral, most distinct 

1.\pon the Irt3tlial portion of the disk, usually more 

distinct and more closely spaced posteriorly than 

anteriorly. Concentric sculpture developed only in 

the shape of incrementals, most pronounced toward the 

ventral margins. Ligament area usually quite high and 

trigonal. Dental armature heavy. Dental arch high. 

Teeth strong, numerous, normally about 12 on either 

side, the anterior a little more elevated as a rule and 

more strongly arched than the posterior. ~1uscle 

scars very distinct, the anterior rounded, trigonal, the 

posterior rudely quadrate. Posterior buttress exceedingly feeble. Pallial line simple. Interior of 

disk faintly striated radially. Inner edge evenly 

crenate along the lateral and basal margins. 

Dimensions: Altitude, 33.9 millimeters; latitude, 

35.1 millimeters; maximum diameter, 20.6 millimeters. 

Type: U.S. Nat. Mus. No. 352312; figured specimen, No. 352313. 

Type locality: No. 3732, Shell Bluff, Shoal River, 

Walton County, Fla. 

Glycymeris waltonensis is the Shoal River representative of the group of G. subovata Say and was 

included by Dall under his variety plagia. It is, 

however, distinct from plagia by reason of its smaller 

average size, n1ore inflated umbones, and n1ore flattened interradials. In 1nany individuals of waltonens?·s the posterior end is quite strongly produced obliquely and in some of them it is obtusely pointed. 

The radial lineation is com1nonly, as in the type, very 

much sharper on the posterior half of the shell than 

upon the anterior, although this differentiation is developed only in the adults and is not constant even 

in them. There is rather a wide age and individual 

variation in the outline of the ligament area and in 

the dental armature, but the area is inclined to be 

narrow and rather high and the dentition strong and 

regular. 

The characteristic Oak Grove species-Glycymeris 

drymanos Gardner, n. sp.- is a slightly larger, heavier, and more inflated shell. Its outline as a rule is 

more nearly symmetrical and the dorsal arch usually 
38 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

broader. The radial sulci a.re generally deeper and 

persist to the margins. The striations upon the submargins are not inclined to be obsolete, as in G. waltonensis, and there is usually some trace of the secondary or fortuitous sulcation, which is best developed 

in the subspecies grapta. It is difficult to separate 

the young of the two species, for the characteristic 

features of waltonensis are not acquired until maturity, but the stronger sculpture of the Oak Grove 

forms may serve as a reliable diagnostic in any considerable series. 

Glycymeris waltonensis is exceedingly prolific; in 

fact, in the collections under investigation it is the 

most prolific of the Shoal River bivalves. 

Occurrence: Shoal River formation, localities 3856P, 

2645c, 3732a, 3742Pr, 5080c, 5184a, 5195a, 5079c, 5193P, 

5194r, 3733r, ~2238r, 3748r, 9957a, 10603Pr, 10608P. 

Glycymerfs sp. cf. G. americana DeFrance 

A single valve of a species possibly closely allied to or 

possibly identical with Glycymeris americana was found 

at Whites Creek, 6. 7 miles south of Argyle, Walton 

County, Fla. The genus Glycymeris, as we know it on 

the east coast, seems to have undergone remarkably few 

changes between the early Tertiary and the Recent 

times. The presence of even the single valve marks 

the introduction of another modern species or of a 

closely allied precursor in the uppermost of the Alum 

Bluff faunas. 

Occurrence: Shoal River formation, locality 9957r. 

Glycymeris pectinata (Gmelin) 

Plate IX, Figures 9-12 

1792. Area pectinata Gmelin, Systema naturae, vol. 6, p. 3313. 

1841. Pectunculus aratus Conrad, Am. Jour. Sci., 1st ser., vol. 

41, p. 346. 

1845. Pectunculus aratus Conrad, Fossils of the medial Tertiary of the United States, p. 62, pl. 34, fig. 2. 

1853. Pectunculus pectiniformis D'Orbigny, in De la Sagra, 

Histoire physique, politique et naturelle de 1 'tle de 

Cuba, Mollusques de Cuba, vol. 2, p. 313. 

1856. Pectunculus aratus Conrad. Tuomey and Holmes, Pleiocene fossils of South Carolina, p. 50, pl. 17, figs. 6, 6a, 6b. 

1858. Pectunculus charlestonensis Holmes, Post-Pleiocene fossils of South Carolina, p. 16, pl. 3, fig. 5. 

1886. Pectunculus pectinatus Gmelin. Dall, Harvard Coll. 

Mus. Comp. Zoology Bull., vol. 12, p. 239. 

1898. Glycymeris pecti.nata Gmelin. Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 612. , 

Not Pectunculus pectiniformis Lamarck, 1819, Histoire naturelle des animaux sans vertebres, vol. 6, p. 53. 

Gmelin described this species in 1792 as foilows: 

A. testa lenticulari inaurita longitudinaliter striata: striis 

1aevibus. * * * 

Habitat in Oceano Americana, pectunculo affinis, at testa 

minore magis convexa, fusca, spadicea, aut lutea punctata, 

maculata, nebulosa, aut undulata, intus subfusca aut alba. 

Conrad in 1845 added the following details: 

Ovate, with about 28 rounded ribs, about as wide as the 

interstices and crossed by wrinkled lines; anterior margin obliquely truncated; extremity with a slightly prominent obtuse 

angle, beneath which the margin is obliquely truncated inward; 

posterior margin obliquely truncated above; cardinal teeth 

prominent, closely arranged, angulated; basal margin with 

about 15 wide remote crenae. 

Locality, Wilmington, N. C. 

Allied to P. pectinatus Lamarck, but the ribs are narrower, 

more remote and prominent. 

Figured specimen: U.S. Nat.11us. No. 325491 (Neills 

Eddy Landing, N.C.). 

The Shoal River representatives are rather large, 

heavy, medially inflated, and angular in o11tline. The 

umbones are small but full, orthogyrate, acute, and 

proximate at their tips, subcentral in position. The 

dorsal margins are short and form as a rule a continuous straight line. Their angle of union with the 

posterior lateral margin is rather sharper than with 

the anterior. The anterior lateral margin merges 

gradually into the upcurved base, whereas the posterior obliquely truncates the posterior end of the 

shell for about two-thirds the distance from the umbones to the base line. The base line is almost 

straight medially and more strongly upcurved in front 

than behind. The radials are prominently elevated, 

somewhat flattened upon their summits, running wider 

than the interradials, generally 20 or 21 in number, 

narrower and a little more crowded laterally, especially 

upon the posterior margin. The concentric lamination upon fresh specimens is very fine. The ligament 

area is small and rather high, the grooves generally 

3 or 4 in number. The teeth are strong, obtusely 

A-shaped, and arranged in two series of about 11 

each which converge at an angle not far from 90° 

The muscle impressions are small but distinct and 

very feebly buttressed. The pallial line is also distinct, and there is the usual fine radial striation upon 

the interior. The basal and lateral margins are 

coarsely crenate in harmony with the external ribbing, the crenulations dying out as they approach the 

dorsal margins. The altitude of the largest of the 

Shoal River individuals is 15 millimeters, its latitude 

14.5 millimeters. 

This small Glycymeris, so abundant in the later 

Tertiary deposits and in the Recent seas, has not 

been previously reported from the lower Miocene. 

It is represented at the single locality by about half 

a dozen valves. 

Occurrence: Shoal River formation, locality 3742P. 

Outside occurrence: Miocene, Yorktown formation, 

Virginia, North Carolina. Duplin formation, North 

Carolina. Pliocene, Waccamaw formation) North 

Carolina, South Carolina. Caloosahatchee formation, 

Florida. Croat an marl, North Carolina. Pleistocene, 

South Carolina. Recent, Cape Hatteras to Greytown, 

Nicaragua, and Barbados, in 2 to 17 5 fathoms; occurs 

in both deep and shallow water in the West Indies, 

elsewhere in shallow water only. 
PRIONODESMACEA AND ANOMALODESMACEA 39 

Section SCmZODONTA 

Superfamily PTERIACEA 

Family PINNIDAE 

Genus ATRIN A Gray 

1840. Atrina J. E. Gray, Synopsis of the contents of the 

British Museum, p. 151, nomina nuda. 

1842. Atrina J. E. Gray, idem, p. 83. 

Type: Pinna nigra Chemnitz. (Recent in the IndoPacific.) 

Gray characterized the genus in 1842 as follows: 

The Pinna have an elongated shell with a longitudinal crack 

filled with a cartilage in the middle of each valve, and Atrina are 

shorter shells without any such crack. 

Shell thin, fragile, .equivalve, gaping posteriorly, 

cuneate. Umbones sharp, pointed, terminal, anterior. Ligament lodged in a long narrow groove. 

Hinge edentulous. Byssal notch small, situated beneath the umbones. 

Atrina is separated from Pinna, to which it has 

been frequently assigned as a subgenus, by the absence 

of the medial longitudinal sulcation. It is confined 

to the warmer waters and is never abundantly represented. 

The genus apparently began as early as the late 

Paleozoic. The Recent species bury themselves in 

the sand and mud along tropical and subtropical 

shores. Only a single species has been reported from 

the Alum Bluff, but this ranges with some variation 

through both the Chipola and the Oak Grove. Fragments of an indeterminate form occur also in the 

Shoal River. 

Atrina chipolana Dall 

1898. Atrina (~gentea var. ?) chipolana Dall, Wagner Free 

Inst. Sci. Tranlll., vol. 3, pt. 4, p. 662. 

Dall describes this species as follows: 

This form is only represented by fragments. It would appear to attain about the size of A. argentea, but to be somewhat more convex and arcuate. The chief distinction is in 

the sculpture; the dorsal areas of the valves of both have about 

five equidistant radial riblets; the ventral a.reas in argentea 

have a few radial ribs near the middle of the valve, below 

which the sculpture becomes obsolete; in chipolana the ventral 

areas are sculptured with distinct oblique, concentric waves, 

with about equal interspaces; the upper ends of these waves 

terminate abruptly where they meet the longitudinal riblets, 

so that the sculpture of the ventral is strongly contrasted with 

that of the dorsal areas. This form also appears to i_ncrease in 

width more rapidly than the argentea. On the whole, the two 

appear specifically distinct, but a complete description must 

be deferred until hetter material enables the characters to be 

fully elucidated. 

Type: U.S. Nat. Mus. No. 114778. 

Type locality: No. 2213, 1 mile below Baileys Ferry, 

Chipola River, Calhoun County, Fla. 

Conrad's original description of Atrina argentea is 

as follows: 16 

16 Conrad, T. A., Observations on the Eocene formation rtnd description of one 

hundred and five new fossils of that period from the vicinity of Vicksburg, Miss.: 

Acad. Nat. Sci. Philadelphia Proc,. vol. 3, pp. 295-296, 1847. 

Triangular, with straight margins and acute summit; compressed; substance highly polished and silvery; valves with 

longitudinal radii on more than half the disc, about thirteen 

in number; anterior side with rugose, obtuse, oblique, finer 

and more approximate lines. Length 2~. Rare. 

There are no fragments worth figuring, and the 

original description can not be amplified from any 

material furnished by the later collections. It is 

possible that there may be more than an individual 

variation between the Oak Grove and the Chipola 

forms, as the Oak Grove fragments seem to indicate 

a broader, less convex species. 

Occurrence: Chipola formation, locality 2213P. 

Oak Grove sand, locality 2646P. 

Family PEDALIONIDAE 

Genus PEDALION (Bolander MSS.) Huddesford 

1770. Pedalion Huddesford, Duo indices ad synopsin methodicam conchyliorum Martini Lister, Index II, p. 23. 

=Melina Retzius, 1788. 

=Perna Lamarck, 1799. 

Type: Ostrea isognomum Linnaeus. (Recent in the 

East Indies.) 

Shell without well-defined auricles, subquadrangular 

to subcuneate, compressed. Exterior surface lamellar. 

Interior nacreous. Umbones sharp, anterior, terminal. Hinge edentulous. Area wide, furnished with 

a series of elongated cartilage pits set normal to the 

margin. Pallial line simple. Muscular impression 

large, slightly eccentric. 

The genus is sparsely represented 1n the 1-fesozoic 

and Cenozoic faunas. 

The reported occurrence at Oak Grove is the only 

record of the presence of this genus in the Alum Bluff. 

Pedalion solereperta (Maury) 

1910. Perna solereperta Maury, Bull. Am. Paleontology, vol. 

4, No. 21, p. 33, pl. 8, fig. 8. 

Maury describes this species as follows: 

Shell very inequilateral, small, compressed, with the general 

outline of P. ephippium Linnaeus. Unfortunately the only 

valve found is broken, but the portion of the cardinal area that 

remains shows distinctly two of the series of cartilage pits. 

Exterior of the shell with numerous fine radiating riblets not 

appearing over the earlier 5 millimeters of the shell. 

Length of shell 12, width 8 millimeters. 

This appears to be the first true Perna found in the Florida 

Tertiaries. 

Oak Grove, Santa Rosa [now Okaloosa] County, Fla. 

Cornell University collection. 

Both the description and the figure are inadequate, 

but there is nothing to supplernent them in any of the 

later collections. 

Occurrence: Oak Grove sand (Cornell University). 

Family PTERllDAE 

Genus PTERIA Scopoli 

1777. Pteria Scopoli, Introductio ad historiam naturalem, p. 

397. 

Type: Mytilus hirundo Linnaeus. (Recent off the 

coast of England and southward through the Mediterranean.) 
40 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Shell inequivalve, inequilateral, auriculate. Anterior ear comparatively srnall, posterior aliform. 

Byssal sinus under anterior auricle of right valve. 

Exterior surface ahnost smooth, lamellar or striated. 

Interior nacreous. Umbones low but sharp. Hinge 

line elongated, straight. A single cardinal tooth 

placed under the umbone of each valve, commonly 

supplen1ented by a laminar lateral tooth. Ligament 

marginal, partly internal, partly external. Pallial 

line entire. Adductor in1pression subcentral. 

The genus has a vast stratigraphic range-from 

the Silurian onward. The Recent species number 

about 120 and live chiefly in tropical and subtropical 

waters. A1nong them n1ay be rnentioned the Antillean 

pearl oyster, Ptaia, radiata Leach. 

The picturesque narne of the type species was 

doubtless suggested by the outline of the shell, which 

is not unlike that of a swallow on the wing. 

Only a single species has been found sufficiently 

well preserved to receive a nan1e, and even this occurs 

in so fragJnentary a state that it has not been figured. 

Aside from P. ch1~polana, which is apparently quite 

comn1on at the single horizon at which it occurs, there 

is another rather closely related Chipola species and 

also an Oak Grove forrn of the group of the P. mu.ltangula H. C. Lea from the Chesapeake Miocene. 

No trace of the genus has been observed in the Shoal 

River material. 

Pteria chipo.lana Dall 

1898. Pteria (argentea var. ?) chipolan.a Dall, Wagner Free Inst. 

Sci. Trans., val. 3, pt. 4, p. 669. 

Dall describes this species. as follows: 

Small, with a straight hinge line and narro,v, deep ligamentary 

sulcus, the right valve with a small, well-marked cardinal tooth 

fitting into a small pit in the opposite valve; anterior wing short, 

small, with a narrow byssal sinus marked on the auricle by 

a short groove, external surface smooth, the posterior wing 

feebly set off; valves rather compressed, none of the valves 

exceeding 25 millimeters in length. 

It is probable that this represents a species distinct from that 

of Vicksburg, but the material in my possession is insufficient 

to determine the question, but the type of P. argentea shows 

little trace of a byssal sinus and is more inequilateral than our 

shell. 

Type: U. S. Nat. Mus. No. 114881. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Chipola River, Calhoun County, Fla. 

No specimens worthy of figuring are contained· in 

any of the available collections. The Chipola species 

is certainly distinct from the Vicksburg, though no 

additional characters have been obsmTed ex<;ept the 

close, sharp lamination upon the anterior auricle of 

the right valve. There is a second Pttr£a present in 

the Chipola beds, a form more oblique than chipolana 

and Inore delicate but known only from a fragment of 

a right valve. The hinge in this fragment is long and 

straight, the u1nbone narrow and obliquely acute, 

the antPrior auricle rather produced and attenuated 

and crowded with laminae sinuated by the shallow 

byssus, the posterior auricle relatively large and quite 

well defined. The entire known surface with the 

exception of the. anterior auricle is microscopically 

crackled and chased with regularly disposed incised 

lines. The surface is mottled with a reddish brown, 

which seems to be a remnant of the original eolor 

pattern. The ligament sulcus is very shallow and 

the cardinal tooth rude. 

Fragments of a third species oeeur in the Oak 

Grove beds. This form was apparently much thieker 

and hea-vier and had a shell structure similar to that 

of P. multangula H. C. Lea. The naere is pearl-gray 

and highly iridescent, as in the Miocene species, and 

there are traees of similar undulatory growth lines 

and radiating threadlets. The ligament area is wide 

and the armature well developed for the group. 

Oceurrenee: Chipola formation, loealities 2213r, 

2564c, 3419r, 2211P. 

Superfamily OSTRACEA 

Family OSTREIDAE 

Genus OSTREA (Linnaeus) Lamarck 

1758. Linnaeus, Systema naturae, lOth ed., p. 696. 

1799. Lamarck, Prodrome d'une nouvelle classification des 

coquilles: Soc. hist. nat. Paris Mem., p. 81. 

Type: Ostrea edu.Zis Linnaeus. (Reeent off the 

European shores from Iceland to the Adriatic..) 

Ostrea, the eommon oyster, is doubtless by reason 

of its great economic. value the most widely kno,vn 

of the molluscan genera. The shell is inequivalve, 

generally irregular and more or less inequilateral. 

Except in the larval stages it is attaehed by the 

convex left valve. The right valve, which is flattened 

or slightly concave, serves as a eover. The hinge is 

edentulous. There is a single muscle scar, the posterior, and this is subcentral. The pallial line is 

simple but not well defined. 

The genus has been prominent in all the mollusean 

faunas from the Mesozoic. onward. Two hundred 

and forty speeies have been recognized in the Cretaceous alone, and throughout the Tertiary OsiJ·ea 

forms one of the most conspicuous elements of nearly 

everv -fauna. Nevertheless, the later Tertiary species 

are ~f little value as horizon markers because of their 

wide stratigraphic range. As in all attached forms 

the limits of variation are wide. 

The distribution of the oysters in the Alum Bluff 

group is surprisingly local. Only one or possibly 

two of the six species which occur has been found in 

more than one forn1ation. Ostrea haitens,is, the most 

wieldy distributed representative of the genus, is 

abundant in both the Oak Grove and Chipola and is 

present in the Shoal River. Ostrea rugijf'ra Dnll is 

the most eharacteristic member of the group at 

Chipola and may possibly be represented in the fuller's 

earth beds nez.,r Tallahassee. Ostrea pauciplicata is 
PRIONODESMACEA AND ANOMALODESMACEA 41 

apparently restricted to the Oak Grove, whereas 

0. trigonalis, 0. podagrina, and the prolific a. normalis 

Dull (0. mauricensis of authors) are restricted in the 

Alum Bluff section to that portion formerly known 

as the "Hawthorn beds." There is no conspicuous 

development of the genus at any -horizon, and during 

the Shoal River epoch conditions must have been 

decidedly unfavorable. 

Adult shell rarely exceeding 7 centimeters in altitude; radial 

sculpture strongly develop~d on the left valve: · 

Radials on the left valve rarely exceeding 15 in number, 

regularly imbricated by the incrementals. 

Ostrea pauciplicata Dall. 

Radials on the left valve usually exceeding 15 in number; 

concentric sculpture usually feeble and irregular. 

Ostrea rugifera Dall. 

Adult ~hell generally exceeding 7 centimeters in altitude: 

Left valve strongly plica ted radially: 

Shell rather thin__________ Ostrea haitensis Sower by. 

Shell very heavy_ _ _ _ _ _ _ _ _ _ _ _ Ostrea podagrina Dall. 

Left valve nonplicate or feebly and irregularly undulated: 

Outline broadly ovate, irregularly plicate, as a rule; 

ligament area usually low, broad, and flattened. 

Ostrea trigonalis Conrad. 

Outline narrowly ovate, usually elongated, not radially plicate; ligament area usually high, narrow, and 

medially excavated_________ Ostrea normal is Dall. 

Ostrea pauciplicata Dall 

Plate X, Figures 3-4 

1898. Ostrca sellaeformis var. pauciplicata Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 678. 

Dall says: 

Shell fan-shaped with acute beaks, thin, with few (7 to 15) 

-rather large, loosely imbricated radial but not divaricating ribs, 

the scales more or less fluted, thin, and elevated; upper valve 

falcate, with concentric laminae; structure flattish and thin. 

Dimensions: Right valve, altitude, 4 7.0 millimeters; 

latitude, 28.0 millimeters. Left valve of another 

individual, altitude, 55.0 millimeters; latitude, 37.0 

millimeters. 

Cotypes: U.S. Nat. Mus. No. 153874. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

The right valve as well as the left is usually quite 

strongly falcate. Radial sculpture is absent upon the 

upper valve. The external surface of the lower valve 

is very prettily frilled by the free-edged and unusually 

regular concentric laminae. The beaks are compressed, the ligament area is narrow and trigonal, and 

the medial depression is deep. The submargins are 

commonly punctate or minutely nodulated, and the 

single muscle scar is pyriform and rather high. 

The species is well characterized by its thin shell, 

falcate outline, fanlike radials, and uniform concentric lamination. It is more coarsely sculptured 

than 0. rugifera and more regularly sculptured than 

0. haitensis. It seems to be sufficiently distinct from 

0. sellaeformis to deserve generic rank. 

The form is apparently peculiar to the Oak Grove 

horizon. 

Occurrence: Oak Grove sand, localities 2646a, 

5632 c, 5630P, 7054 c, 9961 c. 

Ostrea rugifera Dall 

Plate X, Figures 1-2 

1898. Ostrea sellaeformis var. rug'ifera Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 678. 

Dall describes this species as follows: 

Shell rather thin, irregular, coarsely ribbed, more or less imbricated, margin plicate, form tending to ovate or rounded. 

Dimensions: Right valve, altitude, 61.5 millimeters; 

latitude, 37.0 millimeters. Left valve of another 

individual, altitude, 58.0 millimeters; latitude, 38.0 

millimeters. 

Cotypes: Right valve, U.S. Nat. Mus. No. 114570; 

left valve, U.S. Nat. Mus. No. 114571. 

Type locality: No. 2211, lower bed, Alum Bluff, 

Liberty County, Fla. 

Shell rather small, rudely ovate or ovate-trigonal in 

outline, the lower valve slightly convex and overreaching the flattened upper valve along all but the 

dorsal margins. External surface of left valve normally sculptured with 20 to 25 cordate riblets which 

show a slight tendency to diastomose but are for the 

most part continuous from the umbones to the ventral 

margins. Concentric sculpture manifested in irregular nodulations of the costae and more rarely in imbricating lamellae. Surface of right valve sculptured 

with very thin, closely appressed, concentric lamellae, 

about 30 in number in perfect individuals. Ligament area short and narrow, usually a little twisted; 

hinge edentulous. Submargins finely punctate or 

dentate. Single muscle scar pyriform in outline in 

fresh individuals, posterior in position, a little below 

the median horizontal. Inner margin of left val-ye 

finely crenulated. 

Ostrea ru.gifera Dall is most abundantly developed 

at Alum Bluff and is consistently more regular in outline, relatively broader and more finely ribbed at that 

locality than it is along the Chipola. The Chipola 

River individuals are elongated and are as a rule more 

sparsely ribbed and more conspicuously laminated. 

Some of the end members are separable with difficulty 

from 0. pauciplicata of the Oak Grove. The radials 

of 0. pauciplicata are, however, more undulatory, 

usually broader, and less numerous and the concentric 

laminae more regularly fluted. 

Occurrence: Chipola formation, localities, 2212a, 

2213a,2564°,3419c,9994P,2211Pr,2568r,7183c,3424P 

7468c, 4976r, 4977r, 4986P. 

Ostrea trigonalis Conrad 

1829. Ostrea sp., Lesueur, Walnut Hills fossils, pl. 4, fig. 17; 

pl. 5, fig. 1. 

1854. Ostre.a trigonalis Conrad. Wailes, Report on the agriculture and geology of Mississippi, pl. 14, fig. 10. 
42 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

1855. Ostrea trigonalis Conrad, Acad. Nat. Sci. Philadelphia 

Proc., vol. 7, p. 259. 

1898. Ostrea trigonal is Conrad. Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 681. 

1904. Ostrea trigonalis Conrad. Glenn, Maryland Geol. Survey, 

Miocene, p. 381, pl. 101, figs. 1a, lb. 

1909. Ostrea trigonalis Conrad. Grabau and Shime~, North 

American index fossils, vol. 1, p. 465, figs. 621, a, b. 

(After Glenn.) 

Conrad described this species in 1855 as follows: 

Triangular, flat, surface irregular, with some indistinct radiating lines; muscular impression obliquely suboval, situated 

nearer the summit than the base; margin somewhat ascending, 

submargin carinated. A single imperfect upper valve is all 

that I have seen of this shell but it is widely different from any 

other Eocene species known to me. 

Type locality: Jackson, Miss. 

A few of the excellent plates of Lesueur, a French 

engraver, were distributed privately but never properly published, so that his name would have no 

standing even if he had given one. 

Ostrea trigonalis Conrad is heavy, commonly irregular, and varies widely in outline. The umbones are 

generally subcentral and fairly straight, the hinge 

area rather broad and flat, with a shallow central 

channel. The strong vermicular sculpturing of the 

submargins in front of the hinge area, particularly in 

the right valve, forms one of the best diagnostics of 

the species. The outer surface of the heavy upper 

valve is coarsely wrinkled, that of the lower valve in 

some specimens is smooth, in others sculptured with 

coarse growth lines, and in still others rudely plicated. 

The muscle scar is semioval, and in many specimens 

deeply impressed. 

The species has been reported from the fuller's earth 

beds at Rock Bluff and from Sopchoppy. It is a 

poorly characterized form, not sufficiently well preserved to be identified with assurance. 

It is quite possible that the few valves in question 

may be more properly referable to the less ponderous 

Ostrea haitensis Sowerby. 

Occurrence: Chipola formation, localities ~256W, 

~7468r, ?6175r, ?6769r, ?6209r. 

Ostrea haitensis Sowerby 

1850. Ostrea haitensis Sowerby, Quart. Jour. Geol. Soc. London, 

vol. 6, p. 53. 

1873. Ostrea haytensis Sowerby. Gabb, Am. Philos. Soc. 

Trans., vol. 15, p. 257. 

1866. Ostrea virginica Guppy, Quart. Jour. Geol. Soc. London, 

vol. 22, pp. 576, 577. 

Not Ostrea virginica Gmelin, 1792. 

1898. Ostrea haitensi.~ Sowerby. Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 685 (part). 

1917. Ostrea haitensis Sowerby. Maury, Bull. Am. Paleontology, vol. 5, No. 29, p. 182, pl. 31, figs. 1, 2. 

Sower by described this species in 1850 as follows: 

Testa oblonga, crassa, plicata, plicis paucis (senis ad septenis), 

magnh:;, undulatis, subsquamosis, squamis nonnunquam subtubulosis; limbo interno omnino glabro. 

This species appears to be related to 0. imbricata Lamarck; 

it differs, however, in its general form, which is oblong and not 

orbicular, and in the number of external radiating folds, which 

are only six or seven in our shell. 

Type locality: Near San Jago, Santo Domingo, 

West Indies. 

Shell large, commonly 10 or 12 centimeters across, 

solid but not greatly thickened. Both valves flattened 

and subcircular to broadly ovate in outline, the left a 

little·more convex as a rule than the right and a little 

. broader. Left valve strongly plicate, the right variable, in some individuals similar in sculpture to the 

left, in others almost smooth; plications taking the 

form of sharp, V-shaped ridges, generally six or seven 

in number upon the medial portion of the disk, 

originating at the umbones and growing increasingly 

prominent toward the ventral margin; two to four 

finer costals usually developed near the dorsal margins 

and fortuitous secondaries introduced near the ventral 

margin, either intercalated between the primaries or 

diastomosing from them. Concentric laminae overriding the costals and commonly subspinose upon 

their crests. Ligament area varying from high and 

rather narrow to low and broad but generally small and 

rather flattened submargins, in many specimens finely 

corrugated. Single muscle scar large1 transversely 

elliptical to subcircular, slightly posterior to ventral 

in position. Margins simple in the heavy shells, more 

or less fluted in the lighter. 

Ostrea haitensis Sowerby is characterized by its 

rather large but relatively thin shell and the strong 

and, for an oyster, quite regular radial plications. 

The young are separated from 0. rugifera of the same 

size by the coarser ribbing in the right valve and the 

less closely appressed lamellae in the left. 0. pauciplicata is more falcate and more regularly laminated 

concentrically. 

Oceurrence: Chipola formation, localities 10611c, 

10609c, 10610P, 2212c, 2213a, 2564P, 3419P, 9994r, 

6775P. Oak Grove sand, localities 2646Pr, 5630P, 

7054a. Shoal River formation, localities 3742P, 5618P, 

Ostrea podagrina Dall 

Plate X, Figures 5-6 

1896. Ostrea podagrina Dall, U. S. Nat. Mus. Proc., vol. 18, 

p. 22. 

1898. Ostrea podagrina Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 682, pl. 30, figs. 5, 6. 

Dall described this species in 1896 as follows: 

Shell compact, thick and heavy, wider than high, with very 

short wide beaks, coarsely imbricated surface, inflated shell, 

with three or four strong, wide, rather irregular radial plications; interior smooth, distinctly marginated, with a large subcentral adductor scar; hinge and beak flat, the ligamentary 

area in the flat valve hardly excavated, the edges of the flat 

valve near the cardinal border with two obscurely wrinkled 

projecting crura, which fit into shallow depressions in the 

opposite valve; elsewhere there are no striae or pustules on the 

edge of the valves. Height, 110; width, 100; diameter, 50 

millimeters. 
PRIONODESMACEA AND ANOMALODESMACEA 43 

Type: U.S. Nat. Mus. No. 135127. 

Type locality: No. 2612, west bank Suwannee 

River near Sulphur Springs Station, Lafayette County, 

Fla. 

The altitude of the type is 100.0 millimeters; the 

latitude 110.0 millim~ters. 

This species suggests a massive 0. haitensis. 

Occurrence: Chipola formation, localities 2611 P, 

2612P, 2823P. 

Ostrea normalis Dall 

Plate XI, Figures 3-4 

1898. Ostrea georgiana, forma normalis Dall, Wagner Free lnst. 

Sci. Trans., vol. 3, pt. 4, p. 684. 

1915. Ostrea mauricensis Gabb? Dall, U.S. Nat. Mus. Bull. 90, 

p. 123. 

Not Ostrca mauricensis Gabb, 1860. 

Dall described this species in 1898 as follows: 

The typical 0. georgiana are the enormous senile specimens 

with shells ranging to 2 feet long and 3 or 4 incheh thick. The 

young and really more normal specimens have been overlooked, 

though much more abundant, or referred to other species, 

chiefly 0. virginica, from which they differ by their more 

elongated, usually straight, deeply excavated cardinal area 

and the absence of ribbing on the lower valve in most specimens. 

Dimensions: Right valve, altitude, 95.0 millimeters; 

latitude, 55.0 millin1eters. Left valve of another individual, altitude, 100.0 millimeters; latitude, 50.0 millimeters. 

Cot:ypes: U.S. Nat. Mus. No. 153848. 

Type locality: No. 323, Devil's Mill Hopper near 

Hawthorn, Arredonda County, Fla. 

Shell solid, usually thick, elongated ovate-trigonal 

in outline, sometimes very narrow and rudely cylindric::J.l. Right valve flattened. Left valve feebly 

convex. Umbones narrow and compressed, erect or 

slightly inclined. Component concentric layers usually 

visible both on the disk and along the lateral margin, 

most expanded, as a rule, a little more than half way 

down from the dorsal to the ventral margin, thus 

giving to the exterior a pseudoconvexity which the 

interior does not possess; con~entric laminae probably 

frilled much as in 0. compressirostra Say but with 

the free edges usually broken away. Ligament area 

usually high and narrow, strongly depressed medially 

in the left valve, conspicuously elevated in the right, 

especially toward its ventral extremity. Lateral 

margins well differentiated both by the change in the 

plane of the hinge and in the direction of the incre-· 

mentals; vermicular sculpture rarely developed upon 

the submargins. Single muscle scar semielliptical, 

deeply excavated in the heavier individuals, slightly 

posterior and ventral in position. 

Ostrea mauricensris Gabb, the species to which these 

forms have been commonly assigned, was described 

from a shell 1% inches long from New Jersey. The 

outline is similar to that of many of the individuals 

from Florida, but unlike the vast majority of them the 

ligament area is low, broad, and flattened. The a bundant species in Cumberland County, N.J., the environs 

of Gabb's type locality, is 0. percrassa Conrad, a 

species characterized by just such a hinge as that 

exhibited by 0. ma.uricensis. Although it is difficult 

to prove anything by a young oyster, yet the 

chances are favorable that Gabb's type is the young 

of the species abundant in that vicinity rather than 

the young of a form which has not been reported in 

the adult state from the area north of Hatteras and 

which probably does not occur north of Georgia. 

Furthermore, the contour, habit of growth, and general hinge characters are strikingly similar to those of 

0. georgiana of the earlier Tertiary of the Gulf region, 

and there is quite probably a genetic relation "between 

the forms. They have been kept apart, however, 

because they are so readily separable and because 

of the difference in stratigraphic occurrence. TLe 

species is very abundant at many localities in northwest and central Florida, notably in Leon, Levy, and 

Alachua counties. It is restricted, apparently, to 

those beds formerly grouped under the name of the 

''Hawthorn formation" and now considered as Alum 

Bluff, and to the so-called "Grand Gulf beds" overlying the Alum Bluff in the type section. 

Occurrence: Chipolaformation ("Hawthorn beds"), 

localities 2566P, 3415r, 2302r, 6175P, 6769c, 6776r 1 

6778r, 2324P, 6783r, 361r, 5P, 322P, 6801P, 323r, 369Pr, 

365a, 356a, 2116r, 5629P. 

ISODONT A 

Superfamily PECTINACEA 

Family PECTINIDAE 

Genus PECTEN Muller 

1776. Pecten Muller, Zoologiae danicae, prodromus seu animalium, p. 248. 

Type: Ostrea maxima Linnaeus. (Recent off the 

coast of Europe from Norway to the Straits of Gibraltar). 

Shell approximately equilateral, inequivalve, usually suborbicular, auriculate; right valve, as a rule, 

the more convex, not adherent but attached by a 

byssus. Hinge line straight. Resiliun1 central, internal, triangular. Interlocking grooves and ridges 

diverging from the apex of the resilial pit. Pallial line 

simple. Monomyarian; adductor impression rounded, 

posterior. 

TheearliesttruePecten known is from the Cretaceous. 

The Recent species number more than 200, and their 

distribution is world-wide. 

Pecten does not constitute the conspicuous element in 

most of the Alum Bluff faunas that it does in many of 

the formations of the later Tertiary. '.fhe abundance 

of the large Ghlamys (Lyropecten) sayanu.s gives to the 

Oak Grove fauna the general aspect of that of the Chesapeake, and the Chipola faunas represented in the 

"Sopchoppy limestone" and in the fuller's earth beds 

at Quincy have much the same general make-up. ~n 
44 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

the Chipola along Chipola River, however, and in the 

Shoal River the genus is known only by species of 

small or only moderate dimensions and is not conspicuously abundant. Pecten (Pecten) is represented by 

a single species from the Chipola and fragments of an indeterminate species from the Shoal River and Ghlamys 

(Lyropecten) by a characteristic species in the Chipola 

and another in the Oak Grove. The Oak Grove 

species is probably more closely allied to the Chesapeake Pecten than to any in the other formations of 

the Alum Bluff. The section Nodipecten with one 

species and possibly Ghlamys (Ghlamys) with three are, 

like Pecten (Pecten), most common in the Chipola. 

Ghlamys includes chipolanus, the comm0nest member 

of the genus along Chipola River. In Plagioctenium 

nicholsi from the Shoal River, there is a possible precursor of the P. gibbus group. Pseudamussium is 

present in both the Oak Grove and the Shoal River 

but not in the Chipola. The representatives are very 

closely allied to the common Pseudamussium of the 

Bowden. Amusium, however, occurs only in the 

Chipola. The single species which establishes the 

presence of the group at this horizon is the probable 

precursor of the later Tertiary mortoni. 

External surface radially costate: 

Right valve very strongly convex, broader than high; left 

valve flattened; byssal notch and ctenolium not developed_----- ___ - _____ Pecten s. s., Pecten burnsii Dall. 

Right valve not very strongly convex, usually higher than 

it is broad; byssal notch and ctenolium developed. 

Chlamys s. 1. 

Costals not nodose nor undulated longitudinally, normally exceeding 13 in number: 

Primary costals longitudinally threaded even in 

the adolescents: 

Costals not persisting to the ventral margin 

of the adult; secondary lirae not subspinose ___ Chlarnys (Lyropecteu) sayan us Dall. 

Costals persisting to the ventral mru·gin of 

the adult; secondary lirae subspinose. 

Chlamys (Lyropecten) acanikos Gardner, n. sp. 

Primary costals not longitudinally threaded in 

the adolescents: 

Costals subspinose, normally exceeding 18 in 

number_ __________ Chlamys (Chlamys) sp. 

Costals not subspinose, rarely exceeding 18 

in number: 

Costals feeble, obsolete in the umbonal 

region. 

Chlamys (Chlamys) alumensis Dall. 

Costals vigorous, persistent almost to the 

tips of the umbones: 

Concentric lamination equally 

prominent upon the costal and 

intercostal areas. 

Chlamys (Chlamys) chipolanus Dall. 

Concentric lamination feeble or 

obsolete upon the summits of the 

costals. 

Chlamys (Plagioctenium) nicholsi Gardner, n. sp. 

Costals ,nodose or undulated longitudinally, rarely 

exceeding 13 in number. 

Chlamys (N odipecten) condylomatus Dall. 

External surfaec not macroscopically radially costate: 

Inner surface smooth: 

External surface smooth. 

Pseudamussium defuniak Gardner, n. sp. 

External surface microscopically threaded. 

Pseudamussium diktuotum Gardner, n. sp. 

Inner surface lirate ___________ Amusium precursor Dall. 

Subgenus PECTEN s. s. 

Type: Ostrea maxima Linnaeus. (Recent off the 

coast of Europe from Norway to the Straits of 

Gibraltar.) 

The true Pectens are characterized by the strongly 

inflated right valve, the flat left valve, and the absence of a well-defined byssal notch and ctenolium at 

the base of the anterior auricle of the right valve. 

The radial sculpture is usually vigorous and the concentric lamination more or less obvious. 

Pecten (Pecten) burnsii Dall 

Plate XII, Figure 1 

1898. Pecten (Pecten) burnsii Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 720, pl. 34, fig. 8. 

Dall describes this species as follows: 

Shell resembling P. poulsoni Morton, but smaller, less inflated 

and with larger ears; ribs 14, on the right valve strong, each 

divided by two grooves so as to be tricarinate, the minor keels 

scabrous, the interspaces narrower, with fine concentric sculpture; ears and submargins radially threaded, the ears large, 

subequal, the notch shallow; l€ft valve flat, the ribs angular, 

simple, strong, with fine concentric sculpture; ears large, 

radially finely threaded; interior fluted. Altitude 18, latitude 

19, diameter 6 millimeters. 

In specimens of P. poulsoni of the size of this species tho) 

scabrous tricarination of the ribs has not yet appeared; they 

are quite simple, and number 17 to 20. This is probably CJne 

of those cases where a lineal descendant takes on the adult 

character of the ancestor at an earlier period in its life than the 

ancestor did, a character often indicating senility in the life of 

the species. P. burnsii appears to be rare, and the type disappears entirely from the succeeding horizons, as far as known, 

being replaced in the Miocene by large species such as P. hernicyclicus. 

Type: U.S. Nat. Mus. No. 114781. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Calhoun County, Fla. 

The marked convexity of the right valve and the 

flatness of the loft are sufficient to separate this small 

form from its congeners. The right valves of Pecten 

chipolanus are rather close, but they are not so broad, 

they carry one or two more ribs, and they are much 

more strongly imbricated. The costal groov-es in P. 

burnsii become obsolete at some little distance from 

the umbones and are consequently absent in the 

young forms. The auricles upon the left valve are 

relatively large, subequal, finely striate, and merge 

without any decided break in outline or sculpture into 

the submargins. The posterior auricle of the right 

valve is similar in outline to that of the left, though 

more strongly sculptured radially, but the anterior 

auricle is decidedly narrower and more produced, 
PRIONODESMA.CEA AND ANOMALODESMACEA 45 

threaded with four or five coarse lirae, and cut off 

from the submargin by a deep and narrow byssal 

notch. The anterior auricle in the type is broken, 

though this is indicated neither in the figure nor in 

the description. 

Occurrence: Chipola formation, localities 10609r, 

2212P, 2213P, 2564P, 3419P. 

Pecten (Pecten) sp. indet. 

Indeterminate fragments of the left valve of a true 

Pecten have been found in sufficient abundance in 

vYalton County to establish the subgenus in the Shoal 

River. They indicate a species with an average altitude of about 30.0 millimeters and an approximately 

equal latitude. The flatness of the left valve leaves 

no doubt about the subgeneric affinities of the species, 

but the radial fluting is not unlike that of Ohlamys 

(Lyropecten). 

Occurrrnce: Shoal River formation, localities 9960r, 

9957r, 10u03r, lOGOSr. 

Subgenus CHLAMYS Bolten 

1798. Chlamys .Bolten, .Museum Boltenianum, pt. 2, p. 161. 

Type: Pecten islandicus Muller. (Pleistocene of the 

boulder clays of the northeast coast and Recent from 

the Arctic to Chesapeake Bay.) 

Ohlamys s. l. includes those species with both valves 

more or less convex and a well-developed byssus. The 

anterior. auricle of the right valve is modified to permit the extrusion of the byssus and the ctenolium 

developed to prevent the byssal threads from becoming massed and tangled. 

Cossmahn is possibly right in giving full generic 

rank to this group, though there are so many forms, 

such as Lyropecten, on the border that it does not 

seem wise to disturb the established arrangement without a monographic study of the entire Pecten race. 

Ohlamys is first recognized in the early Mesozoic and 

includes the large majority of Tertiary and Recent 

forms assigned to Pecten in a broad sense. 

Section LYROPECTEN Conrad 1s 

1863. Lyropecten Conrad, Acad. Nat. Sci. Philadelphia Proc. 

for 1862, p. 291. 

Type: Lyropecten estrellanus Conrad. (Miocene of 

the Pacific Coast.) 

Conrad described this species as follows: 

Inequivalve, radiately costate; hinge with a triangular pit 

as in Pecten and diverging prominent teeth on each side the 

ligament cavity. 

The valves are generally large and coarse and both 

of them convex. The costals, unlike those of Ohlam.ys 

s. s., are relatively few in number but very heavy and 

not die hotomous. ' 

13 Lyropecten and the closely related Nodipecten precede Chlamys s. s., because of 

their l'loser relationship to Pecten s. s. 

Xfli\V6 0- .'ill-i 042-A) 

Lyropecten is the dominant group in the Chesapeake 

Miocene, conspicuous both by reason of its abundance 

and the large size of the individuals. The beginnings 

in the lower .rvfiocene are very modest, possibly because 

the group had not reached the peak of its development, possibly because the cooler climate of the 

Chesap.eake was more favorable. The heavy Pectens 

of the Miocene of south Europe, the Gigantopecten 

Roverto and its synonym Macrochlamys Sacco, are 

referable to Pecten rather than Ohlamys because of the 

absence of a byssus. They differ frmn Pecten s. s. 

only in the slight convexity of the left valve. 

Chlamys (Lyropecte'n) sayanus Dall 

Plate XII, Figure 7 

1898. Pecten madisonius sayanus, n. var., Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 725, pl. 26, fig. 6. 

Dall describes this species as follows: 

This form is the precursor in the Upper Oligocene 17 of the 

typical madisonius of the Miocene. It differs from the latter 

in its extreme compression, the ribs, except in the umbonal 

region, being almost obsolete. Altitude 120, latitude 1;35, 

diameter about 16 millimeters. 

Type: U.S. Nat. Mus. No. 135838. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

Ohlamys sayan1ts is larger than any other Pecten 

reported from the Alum Bluff. The umbonal angle 

is relatively broad, and the arc included between the 

dorsal Inargins of the adults approaches 270°. 'l'he 

young are higher relatively, a change in proportions 

which is reflected in the slight concavity of the dorsal 

margins. The ribs in the umbonal region are very 

sharp and narrow but broader and flatter away from 

the umbones and toward the base of the fully adult 

are reduced to feeble undulations. The normal number for the adult is 15. As 'a rule there is a narrow 

medial sulcus, most clearly defined a little less than 

halfway from the umbones to the base, and on each 

side of the sulcus two and toward the base three or 

four fine, subequal threadlets. The threads upon the 

sides of the ribs are finer and sharper than those on 

the summits. The interradials are of approximately 

the same width toward the base as the radials and 

are similarly threaded; the medial lira tends to be a 

little more prominent than the others, thus suggesting 

0. jeffersonius edgecombensis. The auricles are low 

and broad, the posterior very finely and closely lirate, 

the anterior on the left valve less finely and on the 

right valve quite coarsely threaded with 6 to 9 unequal 

lirae. The concentric lamination is sharpest and most 

elevated toward the outer margins and upon the auricles. The byssal notch is very deep, as in 0. madisonius, and the ctenolium well defined by a few prominent serrations. 

17 Lower Miocene of the later correlations. 
46 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

In Chlamys acanikos from the Chipola the ribs are 

more numerous by two or three and do not flatten 

away from the uinbones. The secondary threads are 

fewer, more even, and more spinose, and the intercostal areas more angular. 

P. sayanus is very common and widespread at the 

horizon which it characterizes. 

Occurrence: Oak Grove sand, localities ~646a, 5632°, 

5631P, 5630°, 5633P, 7054a, 9961P, 1Q659P. 

Chlamys (Lyropecten) acanikos Gardner, n. sp. 

Plate XI, Figures 1-2 

Shell rather thin and very easily broken, large and 1 

quite compressed. Umbonal angle acute and approximating 90°, the arc included between the dorsal margins slightly exceeding 180°. Radials narrow, abruptly 

elevated, rounded upon their summits, persistent to 

the outer margin, normally 17 in number, each of them, 

as a rule, cut by two linear sulci which divide the 

summit into three subequal lirae. Sides of ribs and 

intercostal areas also closely lirate, each thread bearing 

a series of small spinose processes, those upon the 

medial thread on the costal and upon the medial 

thread of the intercostal areas the most produced. 

Intercostal areas deep, concave, usually narrower 

than the costals. Inner margins sharply fluted. 

Auricles of moderate size, the anterior in the right 

valve angular, produced, cut off from the submargin 

by a deep byssal notch threaded with 6 or 7 scabrous 

lirations. Anterior submargin very narrow and free 

from ornamentation. Posterior auricle of right valve 

trigonal, cut off from the narrow unsculptured submargin by an acute angle; left auricles larger than the 

right, finely threaded, not sharply separated from the 

similarly sculptured submargins. Ctenolium including 4 or 5 rather prominent denticles. Ligament area 

very narrow. Resilial pit small, trigonal, the lateral 

margins well elevated. Cardinal margin of right valve 

bent over the left. Cardinal crura obscure. Adductor scar large, subcircular, slightly posterior, placed 

well up toward the umbones. 

Dimensions: Altitude, 36.0 millimeters; latitude, 

35.0 millimeters; semidiameter, 7.0 millimeters. 

Type: U. S. Nat. Mus. No. 352450. 

Type locality: No. 7893, Boynton Landing, Choctawhatchee River, Washington County, Fla. 

Larger but less perfect individuals attain an altitude 

of 63.0 millimeters. The species, however, does not 

seein to reach the dimensions of its nearest relative 

Chlarnys madisonius. The costals are usually more 

numerous by two than in sayan us, much more persistent, and less finely sculptured, both longitudinally and concentrically. Pecten pleurinominis Woodring (= P. thetidis Dall) is quite closely allied, though 

the costals of the Bowden species are more numerous 

and the secondary lira tion usually coarser. 

The individuals collected along Chipola River are 

all immature and badly worn. It is the coinmon 

Chlamys, however, at Boynton Landing on the Choc-

"tawhatchee and in the environs of White Springs on 

Suwannee River, Columbia County, and packs the 

fuller's earth beds at Quincy in Gadsden County. 

Occurrence: Chipola formation, localities 10609P, 

10610°, 7893P, 2212P, 2213P, 2566P, 37Q4a, 3173°7 

2302P, 7468r, 6175°, 6769°, 4976°, 6Tl5° 1 6776°1 

360P, . 6800°, 5613°, 6208r, 6209P, 5629a, 6196°7 

6197°, 4986°, 2380P, 7847a. 

Section NODIPECTEN Dall 

1898. Nodipecten Dall, Wagner Free Inst. Sci. Trans., vol. 3, 

pt. 4, p. 695. 

Type: Ostrea nodosa Linnaeus. (Pliocene of Florida; 

Pleistocene and Recent of the Gulf of Mexico and the 

Antilles.) 

Dall defines this section as follows: 

Shell like Lyropecten, but the ribs intermittently nodose, 

with more or less prominent hollow nodes or bullae; radial 

striation pronounced; ears unequal, the posterior smaller, the 

valves often more or less oblique; imbricate surface layer sometimes very marked. 

Chlamys (Nodipecten) condylomatus Dall 

Plate XII, Figures 3-4 

1898. Pecten (Nodipecten) condylomatus Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 729, pl. 34, figs. 14, 15. 

Dall described this species as follows: 

Shell small for the group, subequilateral, slightly inequivalve,• 

the right valve more convex, with 9 to 13 strong, undulated, 

rounded, more or less nodulous, finely radially striated ribs, 

the undulations affecting the whole of the disk, sudden and 

very pronounced, giving a side view of the valve somewhat 

the aspect of a clenched fist; interspaces narrower radially, 

finely threaded, the whole valve with fine concentric lamellation 

somewhat prickly or laminose at the intersections; submargins 

rather wide, radially finely striate; ears small, 'subequal, the 

surface coarsely radially threaded, the byssal ear produced 

with a conspicuous sinus and fasciole; ctenolium well marked; 

inner basal margin fluted by the ribs; cardinal margin with 

two or three strong crural ridges. Altitude 40, latitude 45, 

diameter about 22 millimeters. 

This is an interesting species, peculiar from its small size 

and the abruptness of its knuckle-like undulations. Some 

specimens, however, are but little undulated, and the mutations 

are much the same as occur in other species of the section. 

Type: U.S. Nat. Mus. No. 114776. 

Ty1>e locality: No. 2212, Tenmile Creek, 1 mile west 

of Baileys Ferry, Calhoun County, Fla. 

The difference in the convexity of the valves is 

marked even in the young. The secondary threading 

is very fine and even and closer upon the costals 

than in the intercostal areas. As a rule there are 

from 6 to 8 such threads upon the summits of each 

of the costals in the adults and only 3 or 4 in the intercostals, which run about the same width. The concentric lamination is very fine and even, but not so 

close nor so elevated as in 0. chipolanus. The young 
PRIONODESMACEA AND ANOMALODESMACEA 47 

may be known before the first knuckling by the rela-

. tively low number of ribs and by their comparatively 

abrupt increase in width a short distance away from 

the umbones. The individual from White Beach at 

Osprey is too much compressed and too evenly costate 

to be referred to this species. The specimen from 

Hawkinsville, Ga., was also incorrectly determined. 

The species is characteristic of the Chipola formation, but it occurs in greatly diminished numbers in 

both the Oak Gro-ye and the Shoal River. 

Occurrence: Chipola formation, localities 2212 P, 

2213°, 2564°, 3419°, 9994 P. Oak Grove sand, locality 

996F. Shoal River formation, locality 9957r. 

Sect;ion CHLAMYS s. s. 

Type: Pecten islandicus Muller. (Pleistocene of the 

boulder clays of the northeast coast and Recent from 

the Arctic to Chesapeake Bay.) 

Ohlamys s. s. is characterized by the subequal, 

feebly convex, high, and commonly oblique valves 

sculptured with numerous imbricated or spinose 

radials, dichotomous, as a rule, toward the ventral 

margin. The byssal notch is very defined and the 

pectenidial teeth are strong. 

Chlamys (Chlamys) sp. indet. 

1898. Pecten (Chlamys) kneiskerni Conrad. Dall, Wagner Free 

lnst. Sci. Trans., vol. 3, pt. 4, p. 735 (part). 

Dall described this species as follows: 

In Professor Whitfield's attempt to identify the cast of an 

immature shell named as above by Conrad, the former has 

evidently brought together the young, tmcharacteristic shells 

of several species of Chlamys. Conrad's shell was described 

as having 13 ribs and none on the submargins; Whitfield gives 

the species 15 to 50 ribs and radi~ted submargins. This is a 

range altogether too great for a single species. Probably some 

of Professor Whitfield's specimens were young choctavensis, 

which has an unusually large number of ribs. I have supposed 

a shell from the Jacksonian might represent the unidentifiable 

species of Conrad. This has 25 ribs, divaricating near the base 

wfih rather sparse concentric imbrications; ribs wider than the 

interspaces, entire in the young; valves rounded; ears rather 

small with concentric imbricated radii and rather deep byssal 

sulcus. 

The Chipola individuals tentativeiy referred to this 

species are certainly distinct from the Eocene species 

described and seem to be the young of an unknown 

form. They are relatively high and angular little 

valves, sculptured with 19 or 20 narrow, elevated, 

well-rounded ribs, separated by narrower interspaces. 

A single row of short spinose processes is borne upon 

the summit of each costal and upon each of the coarse 

threads which ornament the auricles. There are 4 or 

5 of these threads upon the right valve and about 

half a dozen upon the left. The ornamentation upon 

them and upon the submargins is sharper than upon 

the disk. 

Occurrence: Chipola formation, locality 2213P. 

Chlamys (Chlamys) chipolanus Dall 

Plate XII, Figure 2 

1898. Pecten (Aequipecten) chipolanus Dall, Wagner Free lnst. 

Sci. Trans., vol. 3, pt. 4, p. 733, pl. 29, fig. 9. 

Dall described this species a.~ follows: 

Shell solid, rounded, plump, with 15 to 17 strong, rounded 

ribs with narrower interspaces which are almost channeled, 

both ribs and channels with continuous fluctuated, sometimes 

crowded, low concentric lamellae; the ribs faintly grooved 

distally on top; the concentric sculpture sometimes strong on 

three or more ribs and almost absent on the intervening ones; 

hinge line wide, ears large, with conspicuous but not deep 

notch, with six or seven coarsely imbricated, close-set radial 

threads on the byssal ear and more numerous threads on the 

others; submargins nearly smooth; cardinal crura strong; 

inner basal margin with strong, short flutings, obsolete above. 

Altitude 25, latitude 25, length of hinge line 18 millimeters. 

Type: U.S. Nat. Mus. No. 114784. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

Chlamys chipolanus offers perhaps a wider range of 

variation than any other of the Alum Bluff Pectens. 

There is a curious tendency in the young forms 

toward the development of the concentric sculpture 

upon every third rib only. None of its congeners 

are very closely allied and Pecten burnsii is decidedly 

broader; the right valve is more convex than· that of 

.chipolanus, and the left valve i-, approximately flat. 

The costals even in the young of acanikos are acutely 

scabrous and in Chlamys Rp. indet. they are more 

numerous and minutely spinose distally. The sculp· 

ture of 0. alu.mensis, on the other hand, both the 

concentric and the radial, is less sharply defined and 

in the umbonal region obsoiete. Ohlamys inaequalis 

acntipict1.ts Woodring from the Bowden beds is possibly 

an analog, though the concentric laminae in this 

species do not override the costals as in well-preserved 

specimens of chipolanus. The group as a whole is 

very much better represented in the earlier Tertiary 

than in the later. It is rather surprising that much 

the most common species of the Chipola should be 

of so early a type. The species seems to be more 

closely allied to Ohlamys than to Aequipecten, urider 

which it was first placed. 

Occurrence: Chipola. formation localities 7893r, 

2212c, 7257r, 2213a, 2564a, 3419°, 7151 r, 2211 P, 7183r, 

~7468P, ~496W, ~2302P, ~3424r, ~6175P, ~6776r. 

Cblamys (Chlamys) alumensis Dall 

Plate XII, Figures 8-9 

1898. Pecten (Chlamys) alumensis Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 740, pl. 34, figs. 10, 11. 

Dall described this species as follows: 

Shell small, thin, \vith compressed, flattish umbones and 

14 or 15 feeble, obsolete ribs on the lower part of the disk 

separated by equal shallow interspaces; the whole surface 

marked with fine concentric lines; ears subequal, concentrically 

striate, not radiated, except the byssal ear, which has five 
48 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

scabrous riblets and a well-marked notch; interior fluted to 

correspond with the external ribs; the cardinal crura developed. 

Altitude reaching 15-18 millimeters in fully adult shells; 

figured specimen 8, latitude 7.5 millimeters. 

This small shell is sufficiently distinct in its characters to 

indicate its specific rank, though it may be that it attains a 

larger size when adult than any of the specimens obtained. 

Cotypes: U.S. Nat. Mus. No. 114580. 

Type locality: No. 2211, Alum Bluff (lower bed), 

Liberty County, Fla. 

In so strongly individualized a group this species 

is well characterized by its lack of character. The 

sculpture is obsolete in the umbonal region and even 

at best has a much worn and subdued aspect. 

Occurrence: Chipola formation, localities 2213r, 

3419P, 2211 c. 

Se~ion PLAGIOCTENIUM Dall 

1898. Plagioctenium Dall, Wagner Free Inst. Sci. Trans., vol. 3, 

pt. 4, p. 696. 

Type: Pecten ventricosus Sowerby =Pecten c?,rcularis Sowerby (Pleistocene of California; Recent 

from Monterey, Calif., to the Gulf of California and 

Payta, Peru). 

Dall described this group as follows: 

Resembling Aequipecten but without radial striation; the 

concentric sculpture in looped lamellae; the ribs strong, frequently ~mooth above; the submargins impressed below the 

subequal auricles; the valves well inflated, with a tendency to 

oblique growth in the adult. 

To this very natural group belong nearly all the shallowwater Pectens of our own coasts, such as P. irradians Lamarck, 

P. gibbus Linnaeus, P. dislocatus Say, P. ventricosus Sowerby, 

P. nucleus Linnaeus, P. purpuratus Lamarck, P. eboreus Conrad, 

P. comparilis Tuomey and Holmes, and numerous other fossil 

species. 

The section is readily separable from Ohlamys s. s. by 

the simple, usually less numerous radials, which do 

not diastomose toward the ventral margin. 

It is interesting to find ·in the youngest of the Alum 

Bluff group an ancestral type allied to P. gibbus, one 

of the most prolific of the east coast Pectens. 

Chlamys (Plagioctenium) nicholsi Gardner, n. sp. 

Pia te XII, Figures 5-6 

Shell rather small, thin but tough, slightly inequivalve, the left valve quite compressed, the right feebly 

inflated. Umbonal angle a little more than 90°. 

Dorsal margins rather short, the posterior slightly 

more produced than the anterior. Ventral arc including more than 180°. Radials 17 in number in each 

valve of the type, though commonly not exceeding 

15, beginning almost at the very tips of the umbones 

and gradually increasing in width and elevation; adult 

ribbing strong and even, the summits of the costals 

broadly rounded or somewhat flattened and forming 

obtuse angles with the sides, the intercostals broadly 

concave and of approximately the same width as the 

costals; secondary threading ordinarily not developed, 

but both costal and intercostal areas exhibiting a 

close ancllnicroscopically fine radial lineation. Incremental sculpture very obscure in the right valve and 

on the costals of the left, the intercostal areas of the 

left valve evenly but not very closely laminated. 

Ventral n1argin scalloped in harmony with the radial 

sculpture. Interior fluted almost to the umbones. 

Submargins narrow, steeply sloping, free from orna-. 

mentation. Auricles of left valve and the posterior 

auricle of the right subequal, well differentiated fron1 

the submargins, and threaded with six or seven lirae, 

which become increasingly coarse toward the hinge 

line and which are rendered more or le$ scabrous by 

the overriding concentric lamellae; byssal ear narrower than the others and nwre coarsely sculptured 

both radially and concentrically. Byssal notch quite 

deep. Ctenolium including four or five denticles of 

moderate prominence; length of hinge line nwre than 

half the maxi1num width of the shell. Right valve 

flexed sharply over the left. Ligament area very 

narrow, persisting almost to the extremities of the 

hinge. Resilial pit very small, trigonal, subumbonal. 

Cardinal crura quite well developed, the surface shugreened in order that they may hold more firmly. 

Monomyarian, the single adductor scar rather s)nall, 

slightly posterior, and placed a little above the median 

horizontal. Pallial line simple, commonly obscure, 

distant fron1 the base. 

Dimensions: Altitude of right valve, 20.6 millimeters; left valve of another specimen 25.0 millimeters. Latitude of right valve, 21.2 millimeters; 

left valve, 25.5 millimeters. 

Co types: U. S. Nat. Mus. No. 352453. 

Type locality: No. 3856, 6 miles west-northwest of 

Mossy head, Walton County, Fla. 

A larger valve from the type locality shows a rather 

fine threading toward the ventral margin 1nost distinct 

in the intercostal areas. There is a moderate range 

of variation in relative dimensions, but the costals 

may number as few as 15 and as many as 191 In 

Chlamys sayanus the secondary sculpture is introduced 

very early in the life of the shell. Ohlamys chipolanus 

is relatively higher as a rule, and the concentric laminae 

are more crowded and more elevated and equally 

prominent upon the costal and intercostal areas. 

Ohlamys n-icholsi ·Gardner, n. sp., is probably an ancestral type of the gibbus group, so abundant and 

diversified in the later Tertiary and Recent faunas. 

The species is by far the most abundant and widespread member of the genus in the Shoal River fauna. 

Occurrence: Shoal River formation, localities 3856a, 

2645r, 3742a, ?5079a, ?5193P,' 9958P, 3748P, 7261 r, 

~7264r, ?5192r, 99GOr, 9957c, 10603a, 5618c, 9959°. 

Subgenus PSEUDAMUSSIUM H. and A. Adams 

1858. Pseudamussium H. and A. Adams, Genera of Recent 

l\Iollusca, vol. 2, p. 553. 

Type: Pecten e.roticus Chernnitz =Pecten pseu.damusium So,verby (Recent. off Ga1nbia, vVest Africa). 
PRIONODESMACEA AND ANOl\tiALODESMAUEA 49 

The shells are small, very thin, and more or less 

translucent. The auricles are low and in the right 

valve unequal, for the anterior is cut by the byssal 

notch. The radial sculpture is feeble or absent altogether, but the surface is in n1any specimens concentrically imbricated. The inner face of the disk is 

sinooth. 

Pseudamussium differs from the other Pectens in the 

absence of a well-defined external sculpture, from 

Amusium in the absence of strong internallirae. 

The subgenus has been reported from the midMesosoic and is still existent. Though never abundant, Pse,udamussium is probably better represented 

during the Eocene, both in this country and in Europe, 

than during any other period. 

There is a laJnentable lack of uniformity in the 

spelling of the name of this subgenus and the name 

of the genus to which it bears so strong a superficial 

resemblanc~. With the continentals, as a rule, we 

have Amussium and Pse,udamussium,· in this country, 

Amtzlsiu,m and Pseudam11.sitztm. I have followed the 

original spelling of the authors, though Bolten was 

doubtless incorrect when he wrote the name of the 

"compass shell" with only one s. The nan1e is derived from the Latin amussium, a horizontal wheel for 

denoting the direction of the wind. 

Pseudamussium defuniak Gardner, n. sp. 

Plate XII, Figures 1Q-12 

Shell very small, rather thick, porcellanous, the 

disk a rude sector of about 90°. Right valve nwderately inflated, obliquely flattened toward the u:mbones. 

Left valve flattened. Umbones acute, rising a little 

above the hinge iine. Anterior dorsal margins acutely 

angulated, slightly more produced than the obtusely 

angulated posterior margins. Surface of disk smooth 

except for exceedingly faint traces of a striation like 

that of Oamptonectes, visible only under high magnification on a single individual. Traces of a blotchy 

color pattern also discernible. Auricles rather small, 

those of the left valve subequal, the anterior 

auricle of the right valve higher and more produced 

than the posterior; anterior auricle cut off from the 

disk by a narrow but well-defined byssal groove. 

Margin sharply elevated along the groove and outlined by an obscure thread; trac~s of one or two more 

threadlets and a feeble concentric lamination commonly visible near the notch; right posterior auricle 

not sharply differentiated from the disk and apparently free from sculpture; left anterior auricle and submargin shagreened with an exceedingly fine concentric 

lamination and radial threading, which becomes obsolete toward the hinge; left posterior auricle and submargin merging smoothly into one another and into 

the disk, faintly lineated away from the hinge line 

but showing no tra~e of a concentric imbrication. No 

trace of a ligament area along the hinge margin. 

Resilial pit minute; provinculum still retained on all 

the individuals in the shape of fine ridges normal to 

the hinge margin, the ventral margin of the provinculum expanding slightly about halfway between the 

ligament pit and the distal extremities of the hinge. 

Adductor scar very obscure, apparently rather small, 

quite strongly posterior, and about midway between 

the dorsal and ventral margins. Pallial line also 

obscure. Inner surface of valve smooth. 

Di1nensions: Altitude of right valve, 3.R Inillimeters; left valve of another individual, 4.6 n1illin1eters. Latitude of right valve, 3. 7 5 n1illimeters; 

left valve, 4.6 ± millimeters. 

Cotypes: U. S. Nat. Mus. No. 352453. 

Type locality: No. 5618, 3% miles southwest of 

De Funiak Springs, Walton County, Fla. 

The relationship of this small form to P. guppyi 

Dall is certainly very close, but it is smaller, the 

right valve is less convex and the left valve more 

flattened than in guppyi. The dorsal margins are 

also less sharply defined as a rule. The Oamptonectes 

sculpture has been observed on only a single individual 

of defuniak and very obscurely on that, and the ventral expansion of the provinculum is not so n1arked as 

in guppyi. The single valve from Oak Grove, which 

was referred by Dall to guppyi, is possibly specifically 

identical. The threading upon the auricles is less 

fine, however, and not so restricted as in defuniak. 

Occurrence: Shoal River formation, localities 7264~", 

10608r, 5618P. 

Pseudamussium diktuotum Gardner, n. sp. 

Plate XII, Figures 13-14 

Shell s1nall, relatively thick, porcellanous; the disk 

a rude sector of about 90°. Right valve moderately 

inflated, obliquely flattened toward the un1bones; 

left valve compressed. Umbones acute, projecting a 

little beyond the hinge line. Anterior extremity 

slightly more produced than the posterior. External 

surface covered with a crowded, microscopieally fine 

threading crossed by sharp and regular incrementals, 

thus forming a rather regular reticulate sculpture. 

Auricles small, those of the left valve not so s1nall as 

those of the right; anterior auricle of left valve more 

sharply differentiated from the disk than the posterior 

auricle; anterior auricle of the right valve larger than 

the posterior and Inore sharply threaded, cut off from 

the disk by a shallow but distinct byssal notch; 

Resilial pit· ·minute. Provinculum still retained in 

the fonn of fine ridges normal to the hinge margin, 

expanding 3lightly midway between the resilial pit 

and the distal extremities of the hinge. Adductor 

sear obscure, posterior in position. Pallial line ill 

defined. Inner margins smooth. 

Dimensions: Altitude of right valve, 3.8 millimeters; left valve of another specimen, 4.2 millimeters. 

Latitude of right valve, 4.0 millirneters; left valve of 

another specimen, 4.5 millimeters. 

Cotypes: U.S. Nat. Mus. No. 352454. 
50 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Type locality: No. 9961, Horse Creek, 1% miles 

south of Oak Grove, Okaloosa County, Fla. 

There is a considerable degree of variation in the 

strength of the sculpture upon this remarkable little 

species. On some specimens the sculpture is almost 

<>bsolete, on others it is very sharply and evenly reticulate. However, the development of any sculpture 

other than the Oamptonectes striation upon the disk 

is sufficient to distinguish this species from all the 

other east coast Tertiary forms. 

Occurrence: Oak Grove sand, locality 9961P. 

Pecten (Pseudamussium) sp. 

1898. Pecten (Pseudamusium) guppyi Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, pp. 718, 755 (part). 

Type locality: No. 2580, Bowden, Jamaica. 

The single left valve from Oak Grove which has 

been included under this species differs from the 

Bowden forms in its lower, broader outline, the less 

fine and more even threading of the auricles, and the 

apparent absence of the Oamptonectes striation upon 

the disk. It is smaller, too, than the Bowden individuals and quite possibly immature. Further 

material must be collected before the species is 

sufficiently well known to determine. It may quite 

possibly prove to be identical with the valves of 

si1nilar dimensions and outline collected from the 

Shoal River in the environs of De Funiak Springs. 

The threading upon the auricles of the Shoal River 

· individuals is even finer than that on the Oak Grove 

valve and becomes obsolete altogether near the hinge 

line. 

Occurrence: Oak Grove sand, locality 2646.r 

Genus AMUSIUM Bolten 

1798. Amusium Bolten, Museum Boltenianum, 1st ed., pt. 2, p. 

165. 

Type: Ostrea pleuronectes Linnaeus. (Recent in 

the Indo-Pacific.) 

The valves are commonly large, thin, and feebly 

convex and like those of the true Pectens are not 

attached by a byssus. Radial sculpture is sometimes suggested by the color pattern but is rarely 

developed and is never strong. A concentric imbrication may be observed in some species, particularly 

toward the ventral margin. The discrepancy in 

ornamentation so common in Pseudamu.ssium is 

reflected in the discrepant coloring in Amusiu,m s. s. 

In Amusium papyraceum, the Recent A-ntillean shell, 

the right valve is white or bordered with pale yellow, 

but the left is a deep reddish or purplish brown. This 

general t~ype of color holds throughout Amusium s. s. 

The lirae developed upon the inner surface of the 

disk are perhaps the most constant diagnostic of the 

genus. 

Like Pecten, Amusium may be traced back to the 

Mesozoic. The thin, internally lirate shells of 

Amusium require a much more specialized habitat 

than the heavy, externally ribbed shells of most of 

the Pecten group, and perhaps for this reason the 

genus is relatively rare. 

Subgenus AMUSIUM s. s. 

Type: Ostrea pleuronectes Linnaeus. (Recent in the 

Indo-Pacific.) 

Amu.sium s. s. is characterized by the rather large, 

feebly convex valves, similar in sculpture or in the 

absence of it, the right valve white or pale, the left 

dark and commonly showing a color pattern. 

Amusium (Amusium) precursor Dall 

1898. Pecten (Amusium) precursor Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 755. 

Dall described this species as follows: 

Nepionic left valve with obsolete radii and often feeble concentric undulations. * * * 

P. precursor is nearly as large as P. mortoni, but slightly 

rougher and more convex when adult, the young are nearly 

orbicular; a distinct trace of Camptonectes striation, near the 

beak and submargins, may be discerned with a magnifier in a 

good light. Altitude 110, latitude 123, diameter 20 millimeters. 

The right valve is much flatter than the other. As the material 

is much broken up, it seemed hardly worth while to figure it. 

Type: U.S. Nat. Mus. No. 114773. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

Fragments are common at the localities on Chipola 

River, but no perfect adult has yet been brought back. 

A faint radial lineation may be discerned upon the 

auricles as well as upon the umbone, but this character as well as most of the others 'is shared by P. 

mortoni. 

Occurrence: Chipola formation, localities 2212c, 

2213c, 2564P. 

Family SPONDYLIDAE 

Genus SPONDYLUS Linnaeus 

1758. Spondyl1fs Linnaeus, Systema naturae, 10th ed., p. 690. 

Type: Spondylu.s gaederopus Linnaeus. (Recent in 

the •Mediterranean.) 

Shell inequivalve, subequilateral, ovate or ovatetrigonal in outline, auriculate, normally attached by 

the right valve, which is, as a rule, more inflated than 

the left. Surface radially sculptured, the costals commonly unequal and irregular and bearing foliaceous 

or spinose processes. Auricles smaller and less sharply 

defined than those of Pecten. Cardinal area higher 

in the right valve than in the left. Ligament alivincular, lodged in a trigonal slit beneath the umbones. 

Dentition typically isodont, the teeth two in number 

in each valve, diverging and interlocking with the 

teeth of the opposite valve. Only a single adductor 

scar retained in the adult. Pallial line simple. 

Spondylus has been found in strata as old as the 

Jurassic and still persists in the tropical and sub-
PRIONODESMACEA AND ANOMALODESMACEA 51 

tropical waters. Though never a prolific group, the 

thorny oysters are conspicuous for their rather large 

size, elaborate ornamentation, and gorgeous coloring. 

Only a single species is definitely recognized in the 

Alum Bluff, a form closely allied to the Spondylus 

bostrychites of Guppy from Santo Domingo and the 

Bowden beds. 

Spondylus chipolanus Dall 

1898. Spondylus bostrychites var. chipolanus Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 758. 

1915. Spondylus chipolanus Dall, U. S. Nat. Mus. Bull. 90, 

p. 125, pl. 19, fig. 1 (part). 

Dall described this species in 1898 as follows: 

The type form of this species has a relatively small number of 

spinose ribs, the intervening ones being free from spines, longitudinally finely striate, and show when very perfect minute 

scales. The adult shell is rather short and rounded and less 

inflated than usual in the genus. The species is remarkable 

for its small hinge area. 

In the variety chipolanus Dall there is no radial striation on 

the interspatial ribs, but rather a concentric sculpture; there are 

many more spinose ribs, the shell is more oval and more inflated, and, as far as the material goes, seems to attain a larger 

size. It may prove distinct with more perfect specimens, in 

which case the varietal name may be taken as specific. 

Type: U.S. Nat. Mus. No. 114817. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Calhoun County, Fla. 

. The Chipola species attains considerable din1ensions, 

nnperfect double valves showing an altitude of 110.0 ± 

millimeters, a latitude of 85.0 millimeters, and a 

maximum diameter of 65.0 millimeters. The right 

valve is quite strongly rounded, the left valve inflated 

or flattened. The sculpture is exceedingly variable 

in detail but invariably ornate. The surface is 

crowded with unequal radial threads, all of them more 

or less spiny and every third or fourth thread heavier 

than the others and bearing long, slender spinose 

processes. The concentric imbrication is very close 

.and for the most part microscopically fine. The 

~ardinal area is higher in the right valve than in the 

left and slit medially by the ligament, which extends 

frmn the tip of the umbones to the ventral margin of 

the hinge, expanding slightly ventrally. The teeth are 

short, very thick and heavy, and slightly hooked at 

their extremities. The teeth of the right valve are 

inclosed in sockets formed by the elevated margins of 

the ligan1ent pit of the left valve and the inner surface 

of the teeth. The muscle scar is very large, roundish, 

and placed a little behind and ventral to the middle. 

The species that occurs at Ballast Point is apparently the true bostrychites of the West Indies, 

The specimen figured in Bulletin 90 is from Chipola 

River and is the type of S. chipolanus. The very 

young right valves are sculptured with overlapping 

concentric laminae, quite unlike anything exhibited 

by the adult. 

Occurrence: Chipola formation, localities 2212r, 

2213P, ?221F. Oak Grove sand, locality ?2646r. 

Spondylus sp. cf. S. bostrychites Guppy 

Fragments of a S pondylu.,s collected at a single 

locality in the Shoal River, indicate a species more 

closely allied than the Chipola speci1nens to S. bostrychites Guppy and possibly identical with it. 

Occurrence: Shoal River for1nation, localities, 9957r, 

10603r. 

Genus PLICATULA Lamarck 

1801. Plicatula Lamarck, Systeme des animaux sans vert?~bres, p. 132. 

Type: Plicatula gibbosa Lamarck=P. ramosa Lamarck. (Recent on the east coast from Hatteras to 

Bahia, Brazil.) 

Shell inequivalve, flattened or slightly convex, 

trigonal to subcircular, commonly irregular, attached 

by the umbone of the right valve, which is the larger. 

Exterior surface generally plicate. Ligament internal, 

lodged in a central cartilage pit between the two 

heavy, divergent, transversely striated cardinal teeth. 

Pallial line entire. Muscular impression simple, 

excentric. 

The genus originated in the early Mesozoic, culminated in the late Mesozoic, and is represented by 

less than a dozen recent species, living for the most 

part in the Pacific and Indian oceans. 

Plicatula is separated fron1 its near relative, Spondylus, by the absence of auricles . 

Plicatula is not uncommon in the Chipola, rare in 

the Oak Grove, and unknown in the Shoal River. 

P. lepidota is known from a single individual. The 

other of the two Alum Bluff species, P. densata Conrad, can not be separated from the specimens included 

under that name from the older "silex beds" nor from 

those occurring in the younger Chesapeake of New 

Jersey, Maryland, and Virginia. 

Surface strongly and regularly plica ted radially. 

Plicatula densata Conrad. 

Surface irregularly sculptured both radially and concentrically, 

not regularly plicate _______ Plicatula lepidota Gardner, n. sp. 

Plicatula densata Conrad 

Plate XIII, Figures 1-3 

1843. Plicatula densata Conrad, Acad. Nat. Sci. Philadelphia 

Proc., vol. 1, p. 311. 

1845. Plicatula densata Conrad, Fossils of the Tertiary formations of the United States, p. 75, pl. 43, fig. 6. 

1863. Plicatula densata Conrad, Acad. Nat. Sci. Philadelphia 

Proc. for 1862, p. 582. 

1895. '!Spondylus inornatus Whitfield, U.S. Geol. Survey Mon., 

vol. 24, p. 34, pl. 5, figs. 1, 2. 

1895. Plicatula densata Conrad. Whitfield, U. S. Geol. Survey 

Mon., vol. 24, p. 35, pl. 5, figs. 3-8. 

1898. Plicatula densata Conrad. Dall, Wagner Free Inst. Philadelphia Trans., vol. 3, pt. 4, p. 763. 

1904. Plicatula densata Conrad. Glenn, Maryland Geol. Survey, Miocene, p. 371, pl. 98, figs. 7-9. 

Conrad described this species in 1843 as follows: 

Ovate, thick, profoundly and irregularly plicated; inferior 

valve ventricose, its ribs acute, with arched spiniform scales; 
52 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

cardinal teeth large, curved, laterally striated, crenulated on 

the margins; larger cardinal tooth in each valve slightly bifid, 

broad; muscular impression prominent. Length lYs inches. 

Locality: Cumberland County, N. J. 

The valves have about ten folds, and the lower valve resembles 

a variety of Ostrea virginiana. 

The animal may be attached by either the right or 

the left valve, and over the area of attachment the 

sculpture is of course obsolete. The form consequently differs greatly, not only in outline but in the 

character of the sculpture, according to the size and 

shape of the object to which it is fastened. In the 

free valves the plications are produced aln1ost to the 

umbones, but in those fixed valves that are attached 

over a large area the radial plications are commonly 

reduced to a narrow frill around the outer 1nargin. 

The inner surface inelude4 within the pallial line is 

chalky white, except for the vitreous n1usele scar. 

Plicatula densata is the co1nmon member of the 

genus in the Alum Bluff fauna. Its nearest relative 

is the even more strongly plicated species Plicatula 

maryinata Say, so abundant throughout the Miocene 

of Virginia and the Carolinas. In that form the radial 

plications range from 3 to 8 and are less prone to 

ramify and become spinose than in densata. In 

P. lepidota Gardner, n. sp., known only from a single 

individual, there is no well-defined radial plication of 

the valve but only a fine and very irregular surface 

ornamentation. 

Occurrence: Chipola formation, localities 7893P, 

2212P, 2213e, 9994P, 498W; Oak Grove sand, localities 

2646P, 7054r, 9961P. 

Outside occurrence: Miocene, "Tampa silex beds," 

Florida. Calvert formation, New Jersey and Maryland. St. Marys formation, Virginia and North 

Carolina. Yorktown formation, Virginia and North 

Carolina. 

Plicatula lepidota Gardner, n. sp. 

Plate XIII, Figure 11 

Shell of moderate dimensions for the genus, rather 

thin, warped, compressed and angular toward the 

hinge, broadly expanded ventrally. Only the left 

valve and the cardinal area of the right known. Cardinal area high and trigonal in the right valve, extremely narrow in the left. Anterior margin of left 

valve finely serrate just below the hinge line. Surface 

sculptured with finely crinkled lan1ellae fluted at more 

or less regular intervals but not with sufficient regularity to form a \veil-defined radial sculpture. Only 

the ventral row of flutings regular in the type and these 

partly dosed and produced into about 15 somewhat 

spinose processes. Inner margins crenulate. Ligament internal, lodged in a small pit sunk deep beneath 

the umbones. Dentition vigorous, the teeth of the 

right valve included between those of the left, the 

anterior tooth a little heavier than. the posterior; sides 

of all the teeth transversely ridged. Monomyarian, 

the single muscle scar very sharply defined, roundish, 

posterior, and a little below the median horizontal. 

Pallial line simple, distinct. Surface within the pallial 

line chalky white except for the vitreous muscle scar. 

Dimensions: Altitude, 29.5 millimeters; latitude, 

30.0 millimeters. 

Type: U.S. Nat. Mus. No. 352446. 

Type locality: No. 2213, 1 mile below Baileys Ferry, 

Chipola River, Calhoun County, Fla. 

Unlike that of the common, coexistent P. densata, 

the surface of P. lepidota is not radially plicate but is 

orna1nented with a curiously irr~gular sculpture not 

unlike that of some of the oysters. The concentric 

la1nellae are irregular in width and spacing and are 

roughened by a microscopically fine, irregular grooving, not continuous as a rule, across the free edge. 

At irregular intervals the edges are sharply fluted, 

though upon the outermost ·laminae the flutings are 

approximately equisized and equispaced. The peculiar· roughened, more or less prickly surface of this 

species is unlike that of any known member of the 

genus. The type is unique. 

Occurrence: Chipola formation, locality 2213r. 

Family LIMIDAE 

Genus LIMA (Bruguiere) Cuvier 

1798. Lima Cuvier, Tableau eh~mentaire de l'histoire naturelle 

des animaux, p. 421. 

Type: Ostrea lima Linnaeus. (Type probably a 

recent shell from the Mediterranean; widely distributed in nearly all the tropical and south temperate 

seas; reported fossil in the Pliocene and Pleistocene.) 

Shell auriculate, auricles unequal. Outline usually 

ovate, scoop-shaped and obliquely truncated laterally. 

Valves closed inferiorly but gaping anteriorly and 

sometilnes posteriorly. Exterior surface rarely 

smooth, generally sculptured with simple or imbricated radial striae. Umbones rather prominent and 

distant. Hinge edentulous. Ligament internal, 

lodged in a subumbonal pit. Pallial line simple. 

Single muscle scar excentric, nearer to the posterior 

than the anterior margin. 

The genus is indicated in the Carboniferous, culminates in the Cretaoeous, and is sparsely represented 

in nearly all the recent seas by white or colorless 

shells, which 1nay be attached by a byssus or may 

swim freely with a motion si1nilar to that of Pecten. 

Fragments sufficiently well preserved to establish 

the presence of the genus in the Alum Bluff have been 

collected, but their specific identity· is uncertain. 

Subgenus LIMA s. s. 

Type: Ostrea lima Linnaeus. (Recent in nearly all 

the tropical and south temperate sefl,s; reported fossil 

in the Pliocene and Pleistocene.) 

Lima s. s. is characterized hy the gaping, inequilateral valves and the edentulous hinge. 
PRIONODESMACEA AND ANOMALODESMACEA 53 

Section MANTELL UM Bolten 

1798. Mantellum Balten, Museum Boltenianum, pt. 2, p. 160. 

Type: Ostrea injlata Gmelin. (Recent in the Mediterranean Sea; reported from the Pliocene of Italy 

by Sacco.) 

jfantellum is characterized by the widely gaping 

anterior margins and the suhmargins which are not 

impressed like those of the typical section. 

Lima hian..~ ( Gmelin), which is commonly cited as 

the type of Mantellum, is not included in Bolten's 

list of 1798. 

Lima (Mantellum) carolinensis Dall 

Plate XIII, Figure 4 

1898. Lima (Mantellum) carolinensis Dall, Wagner Free lnst. 

Sci. Trans., vol. 3, pt. 4, p. 767, pl. 35, fig. 21. 

Dull described this species as follows: 

Shell small, thin, inflated, oblique, with a moderate gape, 

sculptured with concentric lines of growth and rather sharp, 

fine, numerous, somewhat irregular radial threads, obsolete on 

the beaks, absent from the posterior submargin and the anterior 

ears; submargins not impressed. heak prominent, ears small, 

the margin of the gape forming a concave sinuosity in front 

of and below the anterior beak; hinge line short, with a very 

wide pit, its lower margin projecting from the cardinal plate; 

interior radially striate, the basal margin slightly crenulate. 

Altitude 16, latitude 12, diameter 7 millimeters. 

This differs from L. papyria Conrad, from the Maryland 

;\liocene, in the absence of the angle which in the latter species 

modifies the margin just below the anterior ear and in the 

presence of dense radial striation on the anterior submargin, 

while in L. papyria this region is smooth. 

Type: U.S. Nat. Mus. No. 107801. 

Type locality: No. 2025, Darlington, S. C. (Miocene: Duplin formation.) 

The Oak Grove individuals are all in1perfect, and 

n1ost of them are immature. Though it is possible 

that perfect adults might exhibit characters which 

would be of systematic value in separating them from 

the Carolina specimens, there are none preserved in 

the available material. 

Occurrence: Oak Grove sand, locality ~2646 P. 

Outside occurrence: Miocene: Duplin formation, 

Natural vVell, Duplin, N. C., and Darlington, S. C. 

Superfamily ANOMIACEA 

Family ANOMIIDAE 

Genus ANOMIA (Linnaeus) Muller 

1758. Anomia Linnaeus, Systema naturae, lOth ed., p. 700 

(part). 

1776. Anomia l\li.iller, Zoologiae danicae, prodromus seu animalium, p. 248. 

Type: Anomia ephippium Linnaeus. (Recent from 

the Arctic Ocean, off the European shores, to the 

Aegean archipelago; fossil in the Pliocene of England and Italy and the Pleistocene of Scandinavia.) 

ShPll inequivalve, adherent, generally subcircular or 

oblong. Left valve more or less convex, right valve 

flattened. Hinge margin of left valve commonly 

incurved and slightly thickened. Ligament scar found 

directly beneath left umbone. Interior of disk of left 

valve scarred with an adductor and a major and minor 

byssal impression, the major byssal scar being the 

largest of the three and dorsal to the adductor and 

minor byssal scars, which are usually sub equal; interior of right valve containing foramina] opening and, 

ventral to it, the impression of the adductor muscle; 

posterior dorsal margin of right valve carrying an inconspicuous ligamenta! process. Pallial line simple. 

Ancestral forms of this genus have been recognized 

in rocks as ancient as the Devonian. The recent species number about forty and are widely distributed 

along the shores from low water mark to 100 fathoms. 

Anomia has four representatives in the Alum Bluffthree of them restricted to the Chipola and the fourth, 

A. jlnridana, common to the Oak Grove and the Shoal 

River. Only a single species, however, has been recorded from Chipola River, the A. microgrammata of 

Dall, a form separated only varietally from a not uncominon Bowden species. A. glypta, from Boynton 

Landing on the Choctawhatchee, is closely allied to 

micror1rammata. The Suwannee River species, however, has much the aspect of Carolia, though it seems 

to differ in the characters diagnostic of that genus. 

External surface very finely and closely lirate or sulcate: 

Altitude normally exceeding 25.0 millimeters. 

Anomia glypta Gardner, n. sp. 

Altitude not normally exceeding 25.0 millimeters. 

Anomia microgrammata Dall. 

External surface smooth or more or less irregularly lirate or 

plicate: 

Altitude not normally exceeding 40.0 millimeters; color 

greenish ____________________ __ Anomia floridana DaU. 

Altitude normally exceeding 40.0 millimeters; color chalky 

white ___________ _ Anomia suwanneensis Gardner, n. sp. 

Anomia glypta Gardner, n. sp. 

Plate XIII, Figures 6-7 

Shell of moderate dimensions for the genus, thin, 

subcircular in outline, the left valve warped into a 

feeble convexity. Umbones distinct but not conspicuous, the tips placed just within the cardinal border and slightly opisthodetic. Surface crowded with 

a very fine and somewhat irregular radial lineation 

or grooving similar in a way to that of A. microgrammata Dall but more crowded and less uniform, 

equally developed, however, on all parts of the disk. 

Ligament internal, mounted on a low shelly process 

somewhat reniform in outline, the convex surface parallel to the dorsal margin, the distal extremities more 

elevated than the medial portion. Hinge edentulous, 

the cardinal border slightly thickened and arching 

over the ligament pit. Scarred area elongated dorsoventrally, widening toward its ventral margin, which 

falls a little below the median horizontal; major byssal 

scar of approximately the same size and almost directly above the single adductor impression; the minor 
54 THE MOLLUSCAN FAUNA OF THE. ALUM BLUFF GROUP OF FLORIDA 

byssal scar, the smallest of the three, placed a little in 

front of the other two and a little below the intermediate line between them. 

Dimensions: Altitude, 41.0 millimeters; latitude, 

46.0 ± millimeters; diameter of left valve, 5.5 millimeters. 

Type: U.S. Nat. Mus. No. 352449. 

Type locality: No. 7893, Boynton Landing, Choctawhatchee River, Washington County, Fla. 

Anomia glypta suggests a much overgrown A. microgrammata but runs about double the size of that 

species and has a surface ornamentation differing 

slightly in character though almost equally fine. The 

relative dimensions and the arrangement of the scars 

also differs in the two species, the adductor scar running smaller relatively in A. microgrammata and more 

posterior with reference to the major byssal scar. 

The species is known only from the type locality. 

Occurrence: Chipola formation, locality 7893P. 

Anomia microgrammata Dall 

Plate XIII, Figure 8 

1898. Anomia microgram mala Dall, Wagner Free Inst. Sci. 

Trans., vol. 3, pt. 4, p. 783, pl. 35, fig. 11. 

Dall described this species as i'ollows: 

Shell small, irregular, characterized by a fine, almost microscopic, close-set radial striation covering the whole surface and 

flaring away from the medial line of the valve in a somewhat 

wavy manner; the two lower scars on the left valve are subequal and side by side, the major byssal scarlarger, opposite 

the medial line between them; the beak of the left valve is some 

distance within the margin, and the surface where worn appears 

smooth; the striation is only visible under a lens in most cases. 

Altitude 17, latitude 25 millimeters. 

This species is recognizable by its fine, alinost divaricate 

striation, which does not break into pustules near the beaks, as 

in the larger and more coat;sely sculptured A. ephippioides. 

Type: U.S. Nat. ~1us. No. 114824. 

Type locality: No. 2212, Tenmile Creek, 1 mile 

west of Baileys Ferry, Calhoun County, Fla. 

Anomia microgrammata Dall from the Chipola and 

A.floridana from the later Alum Bluff formations bear 

much the same relationship to one another as A. 

acu.leata (Glnelin) and A. simplex D'Orbigny of the 

later Tertiary and Recent fauuas. The regularly 

sculptured Miocene and Recent species run about the 

same dimensions, but the ornan1entation of the A. 

microgrammata is more delicate and more uniformly 

developed than that of A. aculeata. A. glypta, which 

occurs also in the Chipola but is not known from 

Chipola River, is n1uch larger, probably less convex, 

less regularly sculptured, and has an adductor scar 

aln1ost as large as the major byssal scar and almost 

directly below it. 

Occurrence: Chipola formation, localities 2213P, 

2564P, 3419P, 2211r. 

Anomia fioridana Dall 

Plate XIII, Figure 10 

1898. Anomia jloridana Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 783, pl. 35, fig. 7. 

Dall described this species as follows: 

Shell of moderate size, usually rather convex, the surface 

irregular, obsoletely microscopically radially striated, more or 

less irregularly feebly pustular and with obsolete, broken, 

feeble radial plications; the minor byssal scar is above and slightly further back (about half its own width) than the adductor 

scar of the same size; the major byssal scar is rounded and much 

larger, situated directly above the minor one, so that the three 

scars are nearly in one dorsoventral line; the beak of the left 

valve is at the cardinal margin. Altitude of largest specimen 

35 millimeters, latitude 39 millimeters. 

This species is ~ntermediate in size and character between A. 

microgrammata Dall and A. ruffini Conrad. It is smaller and 

less sculptured than the latter, which also wants the microscopic 

striation; it is larger, less sharply striated, and has the beak and 

scars situated differently from the former. Many of the 

specimens still retain some of the original greenish coloration. 

Type: U.S. Nat. ~1us. No. 135845. 

Type locality: No. 2646, Oak Grove, Yellow River, 

Okaloosa County, Fla. 

The sculpture of A. _jloridana seems to be of much 

the same fortuitous character as that of A. simplex 

D'Orbigny. No difference can be detected between 

the Oak Grove and Shoal River species. The greenish 

color is very characteristic of this species and very 

unlike anything observed in any of its congeners. 

Occurrence: Oak Grove sand! localities 2646a, 5632P, 

563F, 5633P, 7054P, 3749r. Shoal River formation, 

localities 5079c, 3733P, 9958r, 5192P, 9960c, 9957c, 

10603a, 10608r. 

Anomia suwanneensis Gardner, n. sp. 

Plate XIII, Figure 5 

Shell nacreous, chalky white or talcose, very large 

for the group, the left valve warped into a moderate 

convexity, suborbicular in outline. Umbones inconspicuous, scarcely interrupting the normal curvature 

of the valve; the tips of the umbones set just within 

the 1nargin. External surface smooth except for concentric lamination, most distinct toward the ventral 

margin. Ligmuent mounted on very low, shelly 

crests, n1ost elevated distally; ligament scar broadly 

conic or horseshoe-shaped, the apex of the cone directly 

beneath the umbones, the cardinal margin arching 

over it; ventral margin of scar concave; lateral 

margins not elevated. Hinge edentulous; cardinal area 

indicated by a thickening of the margin, the component layers showing up in cross section. Scarred 

area ovate to spatulate, widening ventrally, the outer 

layer retaining the impressions broken away in all 

available material. 

Dimensions: Altitude, 45.0 ± millimeters; latitude, 

.52.0 millimeters; diameter (left valve), 14.0 nlillimeters. 
PRIONODESMACEA AND ANOMALODESMACEA 55 

Type: U.S. Nat. Mus. No. 352448. 

Type locality: No. 4976, White Springs, Suwannee 

River, I-la1nilton County, Fla. 

This large form suggests Garolia. Unfortunately the 

best diagnostic generic charactera have not been preserved. Only the left valve has been collected, which 

indicates that the right valve is thin and delicate, 

like that of Anomia rather than that of Garolia. The 

ligament attachment of the right valve and the foraminal characters are consequently unknown. The 

area that incloses the adductor and byssal scars is 

elongated dorsoventrally, the characteristic outline in 

Anomia, though the individual scars have not been 

observed. In Garolia there is a single subcircular 

adductor scar nearly central in position. The species 

is much the largest of the genus that has been reported 

frmn the Alum Bluff. One individual from the type 

locality exhibits a fortuitous radial threading in the 

umbonal region. 

Occurrence: Chipola formation, localities 3424r, 

6175c, 6769c, 4976P, 6775P, 6778P, 6776r. ~Oak Grove 

sand, locality ~3385r. 

Genus PODODESMUS Philippi 

1837. Pododesrnus Philippi, Wiegmann, Archiv Naturgeschichte, 

vol. 1, p. 385. 

Type: Pododesmus decipiens Philippi= Pododesmus rudis Broderip. (Recent in the West Indies.) 

Th,e genus resembles Placunanomia in the possession of a simple conspicuous byssal scar but differs 

frorn it in the single hinge line, the small open foramen, 

and the coarsely wrinkled but not plicated external 

surface. 

Paranomia Conrad from the eastern Cretaceous 

is very close to Pododesmus, but there is no definite 

proof of the presence of the genus in strata earlier 

than the Tertiary. The Recent representatives, like 

the fossil, have a meager distribution. 

Only a single species has been established from the 

Alu1n Bluff, and that is restricted in its known distribution to the type locality at Rock Bluff. on 

Chattahoochee Hiver. 

Pododesrnus rudis (Broderip) Gray 

Plate XIII, Figure 12 

1834. Placunanornia rud£s Broderip, Zool. Soc. London Proc. 

for 1834, p. 2. 

1837. Pododesmus dccipiens Philippi. Wiegmann, Archiv Naturgeschichtc, vol. 1, p. 386, pl. 9, figs. la-d. 

1849. Placunanomia rudis Broderip. Gray, Zool. Soc. London 

Proc. for 1849, p. 120. 

1849. Placunanornia abnormalis Gray, idem, p. 121. 

1859. Pl[lcunanornia rudis Broderip. Reeve, Conchologia 

Iconica, vol. 11, Placunanornia, pl. 1, fig. 2. 

1859. Placunanornia echinata Broderip. Reeve, idem, pl. 1, 

fig. 1. 

1859. Placunanomia abnormalis Gray. Reeve, idem, pl. 3, 

figs. 14a, 14b. 

1859. Placunanornia harfordi Reeve, idem, pl. 2, figs. Sa, 8b. 

1898. Pododesmus rudis Broderip. Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 779. 

Broderip described this species in 1834 as follows: 

Plac. testa sordide alba, crassa, concentrice irregulariter 

corrugata, intus nitide polita; alt. 1Ys, long. 16/s, lat. %poll. 

Hab. in India Occidentali. 

Dall in 1898 gives the following details: 

This shell resembles Anomia aculeata externally, from which 

it is distinguished by its small, often obsolete, byssal foramen, 

and by having only two muscular impressions-one large and 

conspicuous, which is the mark of the modified byssal muscle, 

and another below it, smaller and hardly distinguishable on a 

fresh polished specimen, which is due to the adductor. 

The external sculpture of Pododesmus is more 

strongly rugose than that of the average Anomia 

aculeata Gmelin. The single valve dubitably referred 

to P. rudis does not retain enough of its diagnostic 

characters to make the determination convincing. 

The two valves from the Chipola formation referred 

to this species in former check lists are imperfectly 

preserved specimens of an indeterminate species of 

Anomia. The figured specimen is a Recent valve 

from the Antilles. 

Outside occurrence: Pliocene, Waccamaw formation, North Carolina. Recent: Cedar Keys to Guadeloupe and Santa Catarina, Brazil, in less than 50 

fathoms. 

Pododesrnus scopelus Dall 

Plate XIII, Figure 9 

1898. Pododesrnus scopelus Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 779, pl. 30, fig. 8. 

Dall described this species as follows: 

Shell large, irregular, taking the form of the object to which 

it adheres, the upper valve convex, with rude, irregular radial 

threads or unequal riblets, close-set and frequently broken up 

so as to appear vermicular; interior smooth, with two muscular 

impressions rather feebly impressed, the site of the resilium 

deeply impressed and extending behind the cardinal margin; 

attached valve concave, irregular, the foramen small and 

elongate, probably eventually closed, the chondrophore projecting partly over it in our specimens; space between the 

valves very small. Altitude 44, latitude 58, diameter 7 millimeters. 

This species is one of the few characteristic fossils which 

are preserved at Rock Bluff and has not occurred at Oak 

Grove or Alum Bluff in the same horizon, which may be explained by the fact that the bed at Rock Bluff is an old oyster 

reef, in which only Ostrea, Turritella, the present species, and 

fragments of Pecten and Balanus are preserved. The matrix 

is ill adapted to conserve fossils in their perfections, and the 

specimens of Pododesrnus are very irregular and mostly shattered 

by internal movements of the marl. 

Type: U.S. Nat. Mus. No. 115732. 

Type locality: No. 2566, Rock Bluff, Chattahoochee River, Liberty County, F~a. 

No new material referable to this species has been 

collected since the description was first published. 

Occurrence: Chipola formation, locality 2566 c. 
56 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Genus CAROLIA Cantraine 

1838. Carolia Cantraine, Acad. roy. sci. Bruxelles Bull., vol. 5, 

p. Ill. 

Type: Garolia placunoides Cantraine. (Eocene of 

Egypt.) 

The dedication of the genus to Charles Bonaparte is 

rather interesting: 

Je dedie ce genre a Charles Bonaparte, prince de Musignano, 

tant comme un hommage rendu a ses talens, que comme un 

gage de ma reconnaissance pour la bienveillance dont il daigne 

m'honorer. 

Dall describes the genus as follows: 19 

Shell thin, nacreous, with radiating striae, the right valve 

flattened; resilium rounded-triangular, internal, large, attached 

in the right valve to a pedunculate chondrophore seated on the 

anal side of the umbo and extended adorally so as to bring the 

middle of the resilium in the median line of the valve; in the left 

valve the resilium is attached in the cavity of the umbo, leaving 

a broad fan-shaped, thickened scar of attachment-, of which the 

anterior and posterior margins are elevated into diverging 

lamellae. In the young stage the right valve is perforated for 

the passage of a byssus or byssal plug, which gradually atrophies, so that in the full-grown shell the sinus and perforation 

are closed with shelly matter and so overshadowed by the 

heavy chondrophore as to be hardly perceptible even as a scar. 

It should be observed that the attachment of the resilium is 

wholly posterior and not the result of the merging of an anterior 

and posterior chondrophore. The scar of the adductor in each 

v~lve is single, orbicular, and nearly central, with two very 

nunute accessory pedal or byssal muscular scars above it in the 

left valve. 

This genus has been discussed by Gray and Fisher, the latter 

giving some instructive figures of the gradual obliteration of the 

sinus and of the analogous early sinus in Ephippium papyraceum. 

For a fine specimen of the Carolia figured by Roziere in 

Savigny's Egypte I am indebted to Lieut. S. l\1. Ackley, 

U. S. N., who obtained it from the Eocene Tertiary bed underlying the desert, about 5 miles west from the bed of the ancient 

Lake 1\:Ioeris, in the Fayoum. It measures 13 by 15 centimeters 

being somewhat wider than high. The chondrophore is almost 

sessile, so short is the peduncle; the scar of the byssal foramen 

is very distinct, about 2 millimeters in diameter and 10 millimeters below the base of the chondrophore. So small is the 

play of the valves that the cardinal border, sensu stricto, 

has ceased to exist, and the convex valve has that margin 

flattened and produced dorsally, taking on a patelliform 

character. The elevated lateral margins of the ligamentary 

scar are clearly of dynamic origin and not developed crura. 

A singular fact is that the convex valve retains several of 

the sessile plugs of a large Anomia and adherent portions of 

their valves. 

This species has no cardinal area, the surface is radiately 

striate and of that talcose aspect proper to Placenta and Ephippiurn; the distal portion of the chondrophore bears traces of a 

reflexed lamina like that we figure for our Floridian form. 

This cl:aractcr again is obviously dynamic .and is probably 

absent m young and perhaps some adult specimens. 

The group has been recognized only in the Eocene 

of Egypt and in the Tertiary of ti1e southeastern 

United States and West Indies. 

19 Dall, W. II., Contributions to the Tertiary fauna of Florida: Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 4, p. 775, 1898. 

Subgenus WAKULLINA Dall 

1895. TVakullina DaJl, U. S. Nat. Mus. Proc., vol. 18, p. 21. 

1898. TV akullina Dall, Wagner Free Inst. Sci. Trans., vol. 3, 

pt. 4, p. 772. 

Type: Carolia ( Wakullina) floridana Dall. (Lower 

Miocene [Chipola formation], Florida.) 

Dall described this group in 1895 as follows: 

Shell with the single chondrophore of }.f onia, the obsolescent 

byssal notch and plug and simple adductor scar of Ephippiurn. 

The sensible but narrow cardinal area of Ephippium is here 

represented by a broad and conspicuous margin; the lateral 

edges of the ligamentary scar in the left valve form narrow, 

elevated crura, and the exterior is destitute of the radiating 

sculpture common to all the other forms of the group, and resembles that of the smooth Anomias. 

Only the type species has been described, and that 

1s apparently restricted to the single horizon. 

Carolia (Wakullina) tloridana Dall 

Plate XIV, Figures 1-5 

1895. Carolia (Wakullina) jloridana Dall, U. S. Nat. Mus. 

Proc., vol. 18, p. 21. 

1898. Carolia (Wakullina) floridana Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 777, pl. 24, figs. 5, 6, 6b. 

7. 7h. 

Dall described this species in 1895 as follows: 

Shell thin, smooth, nacreous, adherent to other bodies, suborbicular, more or less irregular; right valve flattened or concave, especially at the umbo; left valve convex, with a moderately prominent umbo near the cardinal margin; hinge margin 

variable, but always with a transverse flattish area arched in 

the middle over the attachment of the internal ligament; 

exterior irregularly imbricated by the scaly nacreous layers; 

interior smooth, 'vith a large subcentral, nearly orbicular 

adductor scar; the minute scaled byssal foramen, under the 

middle of the chondrophore, connected by a soldered linear 

suture with the upper anterior margin of the valve; chondrophore rounded, triangular, broad, radiately rugose above, 

recurvecl as a thin lamina from the umbo in fully adult specimens, rather closely sessile, and fitting into the umbonal cavity 

of the left valve; left. valve, with the ligamentary attachment 

broadly triangular, marginated by a thin shelly lamina on each 

side, and arched over by the elevated portion of the cardinal 

area; there is no trace of abyssal mmcle scar in adult examples. 

Breadth in either direction about 110; maximum diameter of 

the closed valves, 9 millimeters. 

"Sopchoppy limestone" [Chipola formation] on the banks of 

Deep Creek, ncar the Sopchoppy River, Wakulla County, Fla. 

[No collection number.] 

In 1898 he adds: 

This fine shell, curiously enough, is, so far as known, the only 

species in the Sopchoppy limestone which· retains its shell 

structure, all the other mollusks, so far as observed, being represented only by their impressions in the soft limestone. It is 

interesting to find an Egyptian type in our southern fauna, 

thou~h the only relation between them is, in the writer's 

opinion, that which both hear to the Anomiidae which preceded 

them, and the analogous recent forms which have succeed~d to 

them. The characters upon which Carolia is based are purely 

dynamic and might he expected to occur in a long succession of 

Anomiidae of any region, the several Carolias having no genetic 

connection with each other, as such, any more than the Oregonian Batissa has with those of other continents now living. 
PRIONODESMACEA AND ANOMALODESMACEA. 57 

Cotypes: U.S. Nat. Mus. Ace. No. 154336. 

There is no form with which well-preserved speci-

·mpns of 0. jlorida.na can be confused. 

Occurrence: Chipola formation, localities 2868P, 

4991 c, 2322P, 7468°, 4977P. 

DYSODONTA 

Superfamily MYTILACEA 

Family MYTILIDAE 

Genus MYTILUS linnaeus 

1758. JIJytilus Linnaeus, Systema naturae, lOth ed., p. 704. 

Type: Jfytilus edulis Linnaeus. (Recent in the 

Arctic Ocean and the North Atlantic.) 

Shell thin, equivalve, cuneiform; posterior margin 

rounded, gaping slightly for the strong, coarse byssus; 

beaks anterior, terminal and pointed; valves covered 

with a conspicuous epidermis, in some specimens subnacreous within; surface smooth or sculptured; hinge 

tPC'th sn1all or obsolete; anterior adductor muscle 

impression very small; posterior adductor muscle very 

large; pallial line simple. 

Triassic to Recent. The recent forms are gregarious and usually attached and comprise about 70 

species, which occur most commonly in cooler waters. 

The representation of the genus in the Alum Bluff 

is exceedingly meager. Each of the two species 

observed is known only from casts. 

Apical region not produced and thickened. 

Mytilus s. s., ~liytilus pandt~oni.<: Dall. 

Apical region produced and thickened. 

!II ytiloconcha Conrad, M ytilus (1~! ytiloconcha) incurvus Conrad. 

Section MYTILUS s. s. 

Type: lfytiluR edulis Linnaeus. (Recent in the 

Arctic Ocean an<l the North Atlantic.) 

Shell SJnooth or concentrically sculptured; apical 

region not produced and thickened. 

Mytilus pandionis Dall 

Plate XIV, Figures 6-7 

1398. Myhlus pandionis Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 787, pl. 30, figs. 9, 10. 

Shell large, smnewhat compressed behind, wide, with 

the postPrior cardinal angle in the anterior third; 

cardinal line short, an impressed narrow area in front 

of the benks nearly half as long as the shell; surface 

apparently snwoth (the type is an internal cast), , 

umbone~ acute. Altitude 122, latitude 60, diameter 

36 1nillimeters. 

T~~pe: U.S. Nat. Mus. No. 154344. 

Type locality: White Beach near Osprey, Little 

Sarn~ota Bny, Fla. 

The 1nateriul from White Beach has proved to be 

of Pliocene ruther than lower Miocene age. 

Subgenus MYTILOCONCHA Conrad 

1863. Mytiloconcha Conrad, Acad. Nat. Sci. Philadelphia Proc. 

for 1862, pp. 290, 579. 

Type: .Myoconcha incurt'a Conrad. Miocene (Calvert formation) of Calvert County, 1\fd. 

Conrad described this group as follows: 

Subfalcate,. thick; perlaceous, laminated; hinge thick, elongated; pointed at the apex; an oblique tooth or ridge and parallel 

furrow throughout the entire length of hinge area. 

Mytilus (Mytiloconcha) incurvus Conrad 

1839. 1l1yoconcha incurva Conrad, Fossils of the medial Tertiary of the United States, No. 1, p. 3 of coYer. 

1840. Myoconcha incurva Conrad, idem, No. 2, p. 52, pl. 28, 

fig. 1. 

1854. Mytilus incurvus Conrad, Acad. Nat. Sci. Philadelphia 

Proc., vol. 7, p. 29. 

1863. Mytiloconcha (Myoconcha) incurva Conrad, Acad. Nat. 

Sci. Philadelphia Proc. for 1862, p. 291. 

1863. Mytiloconcha (Myoconcha) incurva Conrad, idem, p. 579. 

1894. ~fytiloconcha incrassata Whitfield, U. S. Geol. Survey 

Mon. 24, p. 38, pl. 5, figs. 10, 11. 

Not M ytiloconcha incrassata Conrad, 1863. 

1898. !lfytilus (Mytiloconcha) incurvus Conrad. Dall, Wagner 

Free Inst. Sci. Trans., vol. 3, pt. 4, p. 789. 

Conrad described this species in 1839 as follows: 

Shell incurved, thick, narrowed toward the apex; posterior 

side with a submarginal furrow; ninge with a narrow straight 

groove for the cartilage, and a broad furrow on the posterior 

side. I .. ength about 4}1 inches. Locality, Calvert County, 

Md. 

Dall, in 1898, said: 

The specimens found in New Jersey are very badly worn and 

young, hence Professor \Vhitfield's identification of them, 

which I believe erroneous. I have never seen a perfect specimen of this singular shell, but the external casts from the 

Upper Oligocene of Florida show its characters admirably. The 

M. incm:.;1wta Conrad is only a rather heavy Myi'ilus. The 

hinge of the present ~'>pecies has two strong teeth in the left and 

one in the right valve, which are obsolete in senile specimens. 

These teeth are produced over the cardinal area as ridges, extending to the apex of the valve, with a furrmv on each side of 

each ridge, a single furrow between the two ridges of the left 

valve. Apart from the furrows an(l ridges the area is flattened. 

Close to the posterior margin the groove of the ligament is continued along the edge of the an~a to the apex. In a specimen 120 

milltmeters long the area is 20 millimeters long and about the 

same in greatest width. The characters are those of ordinary 

~lfytilus but curiously exaggerated. ~fytilus hcsperianus Lamarck, of the Red Crag of Britain, would seem to belong in this 

group. 

~he determination of the casts referred to this 

species has not been verified. The characters preserved are not sufficient to make the identification 

with assurance. 

Occurrence: Chipola formation ("Sopchoppy limestone," Dall), locality ~7 468 r. 

Genus MODIOLUS Lamarck 

1799. Modiolus Lamarck, Prodrome d'une nouvelle classification des coquilles: Soc. hist. nat. Paris Mem., p. 87. 

Type: 1lfytilus modiolus Linnaeus. (Recent in the 

Arctic Ocean and the North Atlantic.) 
58 THE MOLLUSCAN F,AUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Shell equivalve, inequilateral, transversely or obliquely ovate in outline; ligament external, opisthodetic; hinge edentulous; anterior muscle impression 

atrophied; pallial line sin1ple. 

The genus is separated from MytiZ.us by the character of the beaks, which are nontern1inal, wider, and 

rounded anteriorly. It has a long geologic range, at 

least from the beginning of the Mesozoic and possibly 

from the Devonian. The recent species are about 

70 in number and are most abundant in the tropical 

seas. Unlike "Afytilus, the representatives of Modiolus 

are nestbuilders and burrow or spin a woven structure 

from stones and fragments of shells. 

The genus is well diversified in the Alum Bluff, 

though its representation is very n1eager. Three sections have been recognized, each represented by a 

single species. The Oak Grove form is known only 

fron1 frag1nents, but these indicate so fine a species 

that it seems wise to wa1.t for a worthy type. The 

other two sections-Brachidontes and Botula-have 

been observed only in the Chipola. 

Shell smooth; altitude normally exceeding 40.0 millimeters. 

Jfodi-olus U~fodiolns) sp. indet. 

Shell radially sulcate ____ 21f od,iolns (Brachidontes) curtulus Dall. 

Shell smooth or concentrically sulcate; altitude rarely exceeding 

30.0 millimeters __ ? Modiolus (Botula) cinnarnorneus Lamarck. 

Section MODIOLUS s. s. 

Type: ~lfytilus modiolus Linnaeus. (Recent in the 

Arctic Oepan and the ~ orth Atlantic.) 

The section is characterized by the smooth surface 

and hirsute epidermis. 

Modiolus sp. 

1898. ~'Iodiolus cretaceus Conrad. Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 4, p. 792 (part). 

Not 11fodiola cretacea Conrad, Geol. Soc. Pennsylvania 

Trans., vol. 1, p. 340, pl. 13, fig. 2, 1835. 

Fragments of an unusually fine species, which rnust 

attain an altitude at least of 10 centi1neters, occur not 

uncomrnonly at Oak Grove. None of them are 

sufficiently cmnplete, however, for illustration. The 

form is n1oderately inflated apparently, flaring widely 

posteriorly and obscurely alate. The mnbones are 

sharply rounded but probably not so acute as in "Af. 

cretacea. The ridge froln the urn bones to the posterior 

margin seen1s to be less clearly defined. The surface 

is incren1entally sculptured and along the posterior 

wing the laminar ridges stand out quite sharply. 

The genus is also represented in the "Sopchoppy 

limestone" and at Boynton Landing, but probably 

by distinct though allied species. 

Occurrence: Oak Grove sand, locality 2652P. 

Section BRACHIDONTES Swainson 

1840. Brachidontes Swainson, Treatise on malacology, p. 384. 

Type: _itfodiola sulcata Lrunarck. (Recent in the 

Indian Ocean.) 

Brachidontes is characterized by the radially sulcate 

surface and the nonhirsute ep-idermis. 

The name is most commonly spelled Br(J;Chydontes, 

but in Swainson's Treatise it is spelled Brachidontes. 

Modiolus (Brachidontes) curtulus Dall 

Plate XV, Figure 4 

1898. Modiolus (Brachydontes) grarnrnatus var. curtu~us Dall, 

"\Vagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 794. 

Da1l described this species as follows: 

The variety, which more abundant material might show to 

be a distinct species, is stouter, more triangular, with coarser 

and more nodulous ribs and stronger crenulations of the margin. 

Altitude 12, maximum latitude 7, diameter 6 millimeters. 

Shell small but quite solid, cuneate in outline, 

attenuated toward the umbones; flaring and obtusely 

angulated along the posterior margin, the anterior 

margin straight or feebly concave, the base line 

broadly rounded. Umbones very s1nall, subacute, 

aln1ost but not quite terminal. Radials along the 

posterior and ventral margins coarse, heavily corrugated by the incrementals, tending to bifurcate 

toward the outer margin, not far frOln 15 in number, 

those upon the anterior slope almost twice that number 

and consequently much finer and more crowded and 

not dichotolnous. Ligament groove moderately deep. 

Hinge edentulous. Adductor scar ob~cure. Inner 

margins crenate in harmony with the external sculpture, nearly obsolete toward the umbones. 

Type: U.S. Nat. Mus. No. 114.578. 

Type locality: No. 2211, Alum Bluff (lower bed), 

Liberty County, Fla. 

This form is certainly distinct frmn the Ballast 

Point species which is\ almost sub-cylindrical in outline and ornamented with a fine and delicate radial 

threading. The lirae in grammatu._'; are double the 

number of those ornamenting jf. cnrtu.Zus_. and the 

fluting of the inner margins is consequently 1nuch 

finer and 1nore feeble. 

Occurrence: Chipola fonnation, locality 221F. 

Section BOTULA Morch 

1853. Botula Morch, Catalogus Conchyliorum Comes de 

Y oldi, pt. 2, p. 55. 

Type: Jfodiola cinnamomea Lamarck. (Recent m 

the Indian Ocean.) 

Botula may be known by the concentrically sulcnte 

surface and the polished epidermis. 

?Modiolus (Botula) cinnamomeus Lamarck 

1785. 1\J ytilus cinnamorninus Chemnitz, Conchy,lien Cabinet, 

vol. 8, p. 152, pl. 82, fig. 731. 

1819. Alodiola cinnamomea Lamarck, Histoire naturelle des 

animaux sans vertebres, vol. 6, p. 114. 

1898. ? llfodiolus (Botula: cinnarnorneus Lamarck. Dall, 

Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 797. 

1901. ? .Modiolus cinnarnorneus Lamarck. Dall and Simpson, 

Mollusca of Porto Rico, U. S. Fish Commission Bull., 

vol. 1, p. 470. 

1915. Modiolus (Botula) cinnarnorneus Lamarck. Dall, U. S. 

Nat. Mus. Pull. 90, p. 128. 
PRIONODESMACEA AND AN0l\7IALODESMACEA 59 

Lamarck described this species in 1819 as follows: 

l\1. testa subcylindrica, ventricosa, arcuata, utraque extremitate retusa; natibus subprominulis. 

Type locality: Off Nicobar, East Indies. 

Dall and Simpson described this species in 1901 as 

follmvs: 

Shell small, nearly smooth, subrhomboidal and somewhat 

elongated, slightly arcuate, inflated, with a thick, dark chestnut 

epidermi-s, which shows distinct, often dark, rest periods, and is 

darker colored at the posterior end and anterior base; beaks 

full and high, placed at the upper anterior extremity of the 

shell and projecting in front of the anterior end; hinge line 

curved, the line extending around to the anterior base in an 

unbroken curve. 

In 1898 Dall said: 

I am not able to determine whether the East· Indian shell 

usually called M. fuscus Gmelin is the same or distinct specifically. The distribution of boring species is often very wide. 

It is certain, however, that Chemnitz's specimens, on which 

Lamarck founded the species, \Vere West Indian. It seems 

remarkable that this species should be found in the Oligocene, 

but I am not, from my present material, able to find any 

differential characters whatever from recent specimens of the 

same size. 

This form differs from Lithophaga especially by the presence 

of a row of small but well-defined scars, .extending in a radial 

manner toward the lower posterior basal angle of the shell, 

within the pallial line. These almost give the impression, when 

observed casually, of the presence of a pallial sinus. In the 

absence of fresh specimens of the animal I am unable to determine the function of these scars. 

Dall's authority for his assurance that cinnamomeus 

was described from a West Indian shell is not given. 

Chemnitz states in his original description that the 

shell which he figured and to which Lamarck referred 

came from Nicobar in the East Indies. Boring forms 

have an abnormally wide distribution, and this may 

be one of those exceedingly rare species common 

to the warm waters of the Eastern and Western 

Hemispheres. Additional evidence of their specific 

identity is, however, necessary to conviction. In 

view of the doubtful identity of the Recent West 

Indian form with the East Indian and of the fossil 

Floridian and West Indian species with the Recent 

West Indian the presence of a single battered valve 

in the Alum Bluff material does not establish beyond 

question the presence of Lamarck's cinnamomeus In 

the Alum Bluff of Florida. 

Occurrence: Chipola formation, locality 2213r. 

Genus MODIOLARIA Beck 

1840. Modiolaria Beck, in Robert, E., Zoologic d'un voyage de 

recherche en lslande et en Gronlande, p. xxviii, pl. 17, 

figs. 1-4. 

Type: }Jytilus di8cors Linnaeus. (Recent off the 

coast of Greenland and northern Europe.) 

A genus very closely related to Crenella. The 

distinguishing features are the unsculptured area on 

the medial portion of the disk and the more sinuous 

pallial line concomitant with the longer siphons. 

This group of small forms has been found in strata 

as early as the Mesozoic. Although the recent 

species have been reported from nearly all the seas, 

the group is essentially characteristic of the cooler 

waters. 

The evidence of the presence of this genus in the 

Alum Bluff rests upon a single characteristic fragment from Chipola River. 

Modiolaria sp. 

1898. Modiolaria sp. indet. Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 806. 

Dall described this form as follows: 

A single broken valve belonging to this genus was obtamed 

from the Chipola marl. It is a species similar to M. lateral is 

Say, but marked especially by well-cleveloped latticed sculpture 

in the interspaces of the radii. 

No further material has been collected which n1ight 

serve to identify this species. 

Occurrence: Chipola formation, locality 2564r. 

Genus CRENELLA Brown 

1827. Crenella Brown, Illustrations of the conchology of Great 

Britain and Ireland, pl. 31, figs. 12-14. 

1844. Crenella Brown, Illustrations of the Recent conchology 

of Great Britain and Ireland, 2d ed., p. 75, pl. 23, 

figs. 12-14. 

Not Crenella Sowerby, 1842. 

Type: Mytilus decussatus Montagu. (Recent off 

the coast of Greenland and in north Atlantic waters.) 

Brown described this group in 1827 as follows: 

Shell oblong-oval, equilateral, ventricose; beaks obtuse, 

slightly turned to one side; hinge destitute of teeth but with a 

flattened, horizontal, slightly crenated plate on one side of the 

hinge in each valve; right valve with a triangular, horizontal, 

projecting, reflexed plate, and the left one with an oblique 

plait, both of which are a little crenated externally. 

Dall in :t898 gave the following details: 20 

This interesting little group extends through the Tertiary 

and, owing to the little study given to its characters, has received many names. The shell is usually convex and ovoid, 

with more or less in curved beaks, a nacreous inner layer, thin 

epidermis which adheres closely to the shell, and a fine radial, 

often crossed by a concentric striation. In young sheJls the 

provinculum is exceptionally well developed, sometimes recalling the hinge of Nucula by its strong and projecting denticulations. If the shell is thin these become obsolete with growth, 

but in some species are replaced by a series of denticulations 

directly consequent on the impingement of the external sculpture on the cardinal margin, thus repeating a second time in 

the same individual the process by which the provinculum was 

originally initiated in its ancestors. At least that is the way in 

which the writer interprets the facts. When the shell is thick, 

or when the external sculpture is very delicate, no secondary 

denticulations appear in the adult, which is then left with a 

practically unarmect hinge line. The appearance of the provinculum is not dependent on the existence of the external 

sculpture, but the seconctar~r denticulations are so dependent. 

The exterior may be almost perfectly smooth and polished with 

only microscopic striation; finely radially striate without decussation (like C. sericea), decussate, or with the radial sculpture 

?O Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 802, 1898. 
60 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

strong an.... divaricate. Usually the sculpture is uniformly 

distributed over the surface, but occasionally there will be an 

area of unstriated separating two of striated surface, as in 

Modiolaria, but without the impressed boundaries of the btter 

genus. 

The genus ranges from the Cretaceous to the Recent. 

Like the rest of the family it is characteristic of the 

cooler waters. For that reason, doubtless, its distribution in the warn1 waters of the Alum Bluff is exceedingly n1eager. 

Crenella minuscula Dall 

Plate XV, Figure 9 

1898. Crenella minuscula Dall, Wagner Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 803, pl. 35, fig. 22. 

Dal1 described this species as follows: 

• 

Shell minute, thin, inflated, elongate ovate, feebly radially 

striated, the striations apparently diverging from a medial line 

on the disk; not dichotomous; the beaks smooth; inner margins 

crenulate; valves nearly equilateral. Altitude 1.75, latitude 

1.25, diameter 1 millimeter. 

This little shell is rare in the marl and resembles in a general 

way C. divaricata Orbigny, of which it is the precursor, but has 

fainter sculpture and smooth beaks, besides being constantly of 

smaller size, and is more narrow in form than the young of C. 

divaricata of the same length. 

Type: U.S. Nat. Mus. No. 114624. 

Type locality: No. 2211, Alum Bluff Gower bed), 

Liberty County, Fla. 

The smooth prodissoconch can be plainly observed 

in these minute forms. The affinities of the species are 

obviously with the later Tertiary or Recent members 

rather than with the Eocene. 

Occurrence: Chipola formation, 3419r, 7151P, 2211P, 

10660r. 

Genus LITHOPHAGA Bolten 

1798. Lithophaga Bolten, Museum Boltenianum, pt. 2, p. 156. 

Type: Mytilus Z,ithophagus Linnaeus. (Recent in 

the Mediterranean.) 

Shell thin, nacreous, equivalve, strongly inequilateral, transversely elongated, more or less cylindrical 

in outline. Umbones strongly anterior, but not 

ter1ninal. Anterior extremitv rounded. Posterior 

extren1ity rostrate or cuneif~rm. External surface 

smooth or feebly sculptured concentrically. Ligament 

sub1narginal. Hinge edentulous. 11uscle impressions 

unequal, indistinct. 

The genus has been reported from strata as far 

hack as the Carboniferous. The recent species number 

less than 50 and are confined to tropical arid subtropical waters. 

The young are attached by a byssus but in the 

later stages usually perfors.te coral colonies, the shells 

of larger bivalves, or even the solid rock. Two of the 

five subgenera into which the group has been divided 

are incrusted with a dense calcareous covering in the 

adult stages. The cavities which they ~xcavate are 

characteristically flask-shaped in outline. The perforations in the columns of the temple of Serapis, 

which served Lyell for his classic illustration of changes 

in the level of the sea, were made by Lithophagae. 

Lithophaga is known in the Alum Bluff by a· single 

species, which is represented in the available collections by double valves from the Oak Grove and by a 

single valve fr01n the Chipola at Boynton Landing. 

Lithophaga oryzoides Gardner, n. sp. 

Plate XV, Figure 10 

Shell very small and very thin, inflated, subcylindrical in outline, tapering slightly toward the extremities 

so that in outline and dimensions it is not unlike a 

grain of rice. Umbones very low and inconspicuous, 

following the curvature of the umbonal extremity and 

scarcely interrupting it. Posterior margin expanded 

slightly medially. Anterior n1argin approximately 

straight. Ventral extremity a little more narrow 

than the dorsal and less broadly rounded. Maximum 

inflation of valves slightly ventral to the umbones, 

gradually dying out posteriorly. Anterior slope steeper 

than the posterior. Surface smooth excepting for incrementals and more or less exaggerated resting stages. 

Ligament groove submarginal, very obscure. Hinge 

edentulous. Scars of soft parts not discernible; interior 

highly polished. Shell so thin that the surface is 

faintly rippled by the growth stages which corrugate 

the exterior. 

Dimensions: Altitude, 5.7 millimeters; latitude, 

2.6 millimeters; diameter, 3.1 millimeters. 

Type: U.S. Nat. 11us. No. 352447. 

Type locality: No. 2646, Oak Grove, Yell ow River, 

Okaloosa County, Fla. 

This small species is less elongated than the young 

of L. niger D'Orbigny and shows no trace of the 

characteristic grooving upon the anterior slope. There 

is no other form in the Alum Bluff which approaches it. 

Occurrence: Chipola formation, locality 789W; 

Oak Grove sand, locality 264W. 

Family JULIIDAE Dall 

Genus JULIA Gould 

1862. Julia Gould, Boston Soc. Nat. Hist. Proc., vol. 8, p. 283. 

Type: J,ulia exquisita Gould. (Recent in the 

Hawaiian Islands.) 

Shell small, porcellanous, transversely ovate, inflated. Un1bones quite prominent, prosodetic, strongly 

anterior in position. Lunule deeply in1pressed. Escutcheon obsolete. Surface smooth or feebly striated 

radially. Ligament marginal or partly internal. 

Hinge edentulous except for laminar extensions of the 

ventral margins of the lunule. Posterior adductor 

scar subcentral; anterior adductor prohahly obsolete. 

Since the puhlication of Julia .floridana Dall, heralded as the first member of the genus to be Jound in 

the fossil state and the first to be found in America, 

a second species has been isolated in the Bowden of 

Jamaica by,Vendell P. Woodring. TheknownRecent 

representatives are Indo-Pacific in distribution. 
PRIONODESMACEA AND ANOMALODESMACEA 61 

Julia floridana Dall 

Plate XV, Figures 1-3 

1898. Julia floridana Dall, \Vaguer Free Inst. Sci. Trans., 

vol. 3, pt. 4, p. 811, pl. 35, figs. 1, 2, 3. 

Dall says: 

Shell small, inflated, smooth, arched above, rounded behind, 

the base nearly straight; the beaks prominent, with a small 

impressed lunule immediately under them; below this lunule 

the valve projects forward to a rather acute point; with the 

exception of the groove for the ligament the hinge line is 

perfectly simple, without teeth or crenulations of any kind; 

the edge of the impressed lunule in the right valve is produced 

into a lamella, wh:ch fits behind a less prominent extension 

of the corresponding margin in the opposite valve; interior 

of the valves smooth, with no trace of muscular or other scars; 

exterior sculptured only by faint incremental lines; inner 

margin of the valves simple, not crenulated; shell substance 

showing no traces of nacreous structure, but rather porcellanous. Altitude 4.5, latitude 6.5, diameter 2 millimeters. 

This species evidently belongs to the same restricted group 

as the original Prasina borbonica of Deshayes. The chief 

difference is that the impressed lunule is smaller and not so 

deep and that its margin in the left valve is not elevated 

into so evident a tubercle. Careful scrutiny of more than 20 

valves collected failed to show any satisfactory muscular or 

pallial scars. 

Cotypes: U.S. Nat. Mus. No. 114674. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Chipola River, Calhoun County, Fla. 

This small and unusually well characterized little 

species, is not uncommon in the environs of the type 

locality. 

Occurrence: Chipola formation, localities 2213P, 

3419P. 

Order ANOMALODESMACEA Dall 

Dall gives the following description of this order: 21 

Pelecypods having the mantle lobes more or less completely 

united, leaving two siphonal, a pedal, and sometimes a fourth 

opening between them; siphons "\Vell developed, always at the 

posterior end of the body; two subequal adductor muscles; the 

shell structure nacreous and cellulo-crystalline, rarely with a 

prismatic layer; the area amphidetic or obscure, rarely distinctly divided; the ligament usually opisthodetic, generally 

associated with an internal resilium, chondrophores and lithodesma; valves generally unequal, the dorsal margin without a 

distinct hinge plate, the armature of the hinge feeble, often obsolete or absent; rarely with lateral laminae or well-developed 

dental processe'3; the animals usually sedentary burrowers, hermaphrodite and marine. * * * 

Although this group in the general classification has usually 

been placed after the forms here included in the Teleodesmacea, 

no linear arrangement can properly express their natural relations. This and the preceding order (Prionodesmacea) represent for us lines of parallel development of the most ancient 

origin, while the Teleodesmacea probably took their rise chiefly 

from forms which, genetically, would be included in the present 

order. The modern Anomalodesmacea are nearlv all much 

specialized and their archaic characters veiled by l~ter adaptations. That any have come down to us retaining indications of 

their archaic character is probably due to the burrowing habit, 

which has shielded them from many vicissitudes and checked 

in this way the perfecting processes of selection. 

21 Dall, W. H., Contributions to the Tertiary fauna of Florida: Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 3, pp. 512, 529-530, 1895. 

51459° -26j--5 

The student will understand, therefore, that the present 

group is here regarded as having one general origin with the 

Teleodesmacea, the two being contrasted with the Prionodesmacea, the latter differing more from either than the former 

differ from each other. Part of the original stock has produced 

the perfected types of pelecypods, which have lost all their 

archaic characters and become the Teleodesmacea, while another part, sheltered by peculiarities of station and developing 

adaptive modifications, has lagged behind the others and still 

indicates in some degree the ancient types from which it sprang. 

Superfamily ANATINACEA 

Dall characterizes this superfamily as follows: 22 

Anomalodesmacea having V-shaped reticulate gills; not secreting a calcareous tube external to the shell. 

Section EUSIPHONIA 

Siphons elongate, the lithodesma, when present, at the ant&~o 

rior end of the internal resilium, and external to the mass of the 

resilium. 22 

Family PERIPLOMATIDAE 

Genus PERIPLOMA Schumacher 

1817. Periploma Schumacher, Essai d'un nouveau systeme des 

habitations des vers testaces, p. 115. 

Type: Periploma inaequivalvis Schumacher. (Recent in the West Indies.) 

Shell subnacreous, inequivalve, nearly closed, oval 

or rounded; umbones opisthogyrate; ligament internal, 

supported by two vertically or anteriorly directed 

chondrophores; hinge edentulous;· muscle impressions 

unequal; pallial sinus broad and shallow. 

Dall says: 23 

The genus and its subdivisions show a gradual modification 

of the hinge characters. In Periploma there is a strong, prominent clavicular rib supporting the chondrophore, and in front 

of the latter is a small lunate lithodesma; in Cochlodesma the 

clavicle is obsolescent and in front of the chondrophores there 

is a cartilaginous mass of dark-brown color, uniting the valves 

and occupying the place of the lithodesma, but uncalcified. 

The genus is rare in the Tertiary, whereas the Recent 

forms are for the most part confined to the eastern 

coast of the Americas. 

The group is represented in the Alum Bluff by a 

single abundant but ill-preserved species restricted to 

a single horizon. 

Periploma discus Gardner, n. sp. 

Plate XV, FigurE's 11-13 

Shell large for the genus, thick, nacreous, and so 

exceedingly fragile that the species is known only 

from abundant fragments. Valves rather compressed 

apparently, rudely discoidal in outline. Umbones 

subcentral, opisthogyrate, quite tumid and acutely 

pointed at their apices. An acute ridge apparently 

developed near the apex. Surface incrementally 

wrinkled, commonly with microscopically fine striae 

that cut obliquely across the wrinkles toward the 

ventral margin. Concentric sculpture giving way 

22 Dall, W. H., op. cit, p. 530. 

23 Dall, W. H., Contributions to the Tertiary fauna of Florida: Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 6, p, 1528, 1903. 
62 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

near the lateral :margins to a fine granulation suggestive of Thracia. Ligament internal but obsolete ventrally, supported by two pron1inent spoon-shaped 

chondrophores, produced obliquely backward from 

beneath the tips of the umbones, reinforced by a 

clavate lithodesma. Chondrophores strengthened by 

a rib-like thickening of the shell ventral to the chondrophore and at a low angle to the posterior dorsal margin. Hinge edentulous. Muscle impressions and 

pallial sinus unknown. 

Din1ensions: Altitude 67.0 ± millimeters; latitude 

70.0 ± n1illimeters. 

Type: U.S. Nat. Mus. No. 352445. 

Type locality: No. 3856, 6 n1iles west-northwest of 

Mossyhead, "\Valton County, Fla. 

A new species that occurs abundantly in a fragmentary state is most annoying. If it is nan1ed a perrnanent type must be selected and it must be figured, but 

in the possible event of the discovery of perfect material there may be a permanent cause for regret. On 

the other hand, a species that constitutes a considerable factor in a fauna can not be entirely disregarded 

in a monograph of that fauna. The collections from 

the Shoal Hiver are extensive and were carefully made, 

and the chances for finding perfect individuals were 

probably as good as they will be later. 

There is no trace of the genus at any other horizon 

nor of any but the one species in the Shoal Hiver. It 

is possibly the precursor of Periploma peralta Conrad, 

though it is relatively higher, less compressed, and 

very much thicker shelled. 

Occurrence: Shoal River formation, localities 3856a, 

3733r, 3748r, 9957r, 10603P, 10608P. 

Family THRACIIDAE 

Genus THRACIA (Leach MS.) De Blainville 

1824. Thracia De Blainville, Dictionnaire des sciences naturelles, vol. 32, p. 347. 

1839. Thracia Couthouy, Boston Jour. Nat. Hist., vol. 2, p. 129. 

Type: Thracia corbuloidea De Blainville. (Recent 

in the Mediterranean.) 

Couthouy describes this genus as follows: 

Shell thin, transversely oval, inequivalve, corbuliform, right 

valve the more convex, inequilateral, slightly gaping at both 

extremities; beaks well marked, and inclined a little backward; 

hinge having upon each valve a more or less prominent, horizontal spoon-shaped apophysis, receiving the internal portion 

of a ligament, visible also externally; this internal ligament is 

(sometimes) posteriorly attached to and strongly supports a 

cylindrical ossiculum, in the form of a semicircle. Anterior muscular impression narrow and elongated, united to the posterior, 

which is small and rounded, by a pallial impression strongly 

excavated posteriorly. 

Thracia has had a rather meager representation 

since th~ Triassic. The shells are usually very fragile 

and ill adapted to preservation. The Recent forms 

have been collected from the American and European 

coasts and from the China Sea. 

A sinO'le valve att.ests the existence of the genus h 

during Alum Bluff time. 

Thracia sp. indet. 

A single left valve apparently allied to the small 

Thracia transversa H. C. Lea frmn the 11iocene of 

Virginia but differing from it in the more elongate 

outline and the more coarsely sculptured umbones 

wa.s collected frorn a locality near Shell Bluff on Shoal 

River. Though too irnperfect to describe, it is quite 

sufficient to establish the presence of the genus in the 

Alurn Bluff f.auna. 

Occurrence: Shoal River formation, locality 5079r. 

Section ADELOSIPHONIA 

Dall characterizes this section as follows :

25 

Siphons short, the lithodesma dividing the mass of the 

cartilage mesially. 

Family P ANDORIDAE Gray 

Genus PANDORA (Bruguiere) Lamarck 

1798. Pandora Bruguiere, Tableau encyclopedique et methodique, vol. 1, pl. 250 (no desc.), figs. a-c. 

1799. Pandora Lamarck, Prodrome d'une nouvelle classification 

des coquilles: Soc. hist. nat. Paris Mem., p. 88. Sole 

sp. Tellina inaequivall'is Linnaeus. 

Monotype: Tell ina inaeguivalvis Linnaeus. (Recent in the Mediterranean.) 

Dall described this genus as follows: 26 

The beaks of Pandora are erect and in the adult always more 

or less eroded. The ligament and resilium lie initially beneath 

them. The latter is usually longer, wholly submerged, and 

separate from the ligament except at its starting point. It is 

set in a groove, oblique or nearly vertical, and the edges of the 

groove are usually a little raised. On the anterior si?e o~ the 

ligament, when present, is to be found a long, straphke hthodesma. In Pandora s. s. and Coelodon there is no lithodesma 

developed. The normal number of teeth or laminae in each 

valve would appear to be three, but they may be merged in 

the cardinal border or the raised edge of the chondrophore, so 

that in Pandora s. s., when adult, the left valve appears to be 

without teeth and the right valve has only hvo. The teeth are 

formed, as in other cases, of a shank or lamina and a hook. 

Usuallv these become separated at an early age, forming two 

separate teeth, but in Coelodon the anterior left cardinal not 

only retains its connection with its "hook," but as the shell 

grows the entering angle between the hook and shank, by the 

fusing of the distal edges of the laminae, is, as it were, partially roofed over, a feature of which the most conspicuous examples in other groups occur in the Mactridae. The formulae 

are as follows: 

L io ioio L ioroio L. oroi Cl'd · h ra · r · Coelodon · · Pandora, ---. -. -· "' wp 0 

' R. oiroioi' ' R. oirioi ' R. mo 

The anterior left cardinal in the latter is represented only by 

a callosity on the anterior dorsal border of the valve in front 

of the umbonal notch. In all the groups the laminae have a 

tendency to pedunculation, the bases being nar:ower than 

the distal portion. They are therefore very hable to be 

broken off in opening the valves and are sometimes so interlocked that the animal itself can open the valves but to a 

trifling extent. The ligament is short and bla~k; i: usuall! 

appears to extend over the upper ends of the lammae m a horizontal direction or it may dip obliquely into the valves. In 

one case observed the ends of the ligament descended one in 

front and the other behind the upper end of the resilium, but 

2s Dall, W. H., Contributions to the Tertiary fauna of Florida: Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 3, p. 532, 1895. 

26 Idem, pt. 6, pp. 1516-1517, 1903. 
PRIONODESMACEA AND ANOMALODESMACEA 63 

the normal position is in front of the resilium. The lunule and 

escutcheon when present are compressed and almost linear, the 

dorsal margin of the flat valve usually slightly overlies that of 

the convex valve. The pallial line is in this genus largely a 

misnomer, for the mantle is attached to the shell by a succession of rounded spots which are not continuous; the visceral 

area of the disk may be smooth but is often punctate or radially 

striate and brilliantly pearly. The left valve is the convex 

one, and the ventral margin of the right valve is generally more 

or less flexible, so that the solid portions of the valves come 

together. The pearly layer is overlaid by a conspicuous, often 

partly eroded, prismatic layer, and that by a periostracum 

which in the northern species is often rather profuse and papery. 

The margin is practically entire, but they often have a few radiating threads on the posterior slope of the left valve, while on 

the right valve, especially in Kennerleyia, there are usually 

radial, impressed, somewhat dendritic brown lines. 

The species are usually found in sandy or muddy situations, 

and the group is represented as early as the Cretaceous in 

Europe. 

The genus, though including only about 20 Recent 

specie3, is universally distributed from the Arctic to 

the Indian Ocean. 

Only the single species has been recorded from the 

Alum Bluff, but this occurs rather abundantly both in 

the Oak Grove and in the Shoal River. No trace of 

the genus has yet been found in the Chipola. 

Subgenus KENNERLEYIA Carpenter 

1864. Kennerleyia Carpenter, Zool. Soc. London Proc., p. 602. 

Type: Kennerleyia filosa Carpenter. (Recent from 

N univak Island, Bering Sea to San Pedro, Calif.) 

The subgenus is characterized by the radial ornamentation of the right valve and the development of a 

lithodesma. 

Pandora (Kennerleyia) dodona Dall 

Plate XV, Figure 8 

1903. Pandora (Kennerleyia) dodona Dall, Wagner Free Inst. 

Sci. Trans., vol. 3, pt. 6, p. 1518, pl. 57, fig. 25. 

Dall described this species as follows: 

Shell small; left valve very convex, when adult somewhat 

twisted, attenuated distally, with a slender, blunt rostrum; 

anterior area· defined by an obsolete sulcus and with the central 

area smooth; posterior dorsal area bounded below by a single 

radial thread and somewhat concentrically wrinkled, hinge 

plate normal, disk with the muscular impressions strongly 

marked; right valve slightly concave, with a strong posterior 

dorsal keel, concentrically striated and with a few radial incised lines. Length 12.5 (to 15.0), height 5.2, diameter 2.0 

millimeters. 

This species is somewhat like P. carolinensis Bush, but more 

slender and more enrolled; in fact, in the latter respect our 

other species, recent or fossil, approach it closely only 

exceptionally. 

Type: U.S. Nat. Mus. No. 135848a. 

Type locality: No. 2646, Oak·Grove, Yellow River, 

Okaloosa County, Fla. 

The Shoal River forms run a little larger and a 

little heavier, as a rule, but the differences are so 

slight and the exceptions in both faunas so nurnerous 

that even a subspecific distinction is too fine. 

Occurrence: Oak Grove sana, lOcalities 2646a, 5632P, 

5631P, 7054P. Shoal River formation, localities 3856P, 

3742a, 5195r, 5079c, 7264r, 10603 r, 995W. 

Superfamily POROMYACEA Dall 

Dall 27 characterized this sup,erfamily as follows: 

Anomalodesmacea having modified foliobranch or lamellar 

gills, slightly or not at all reticulated, and frequently degenerate 

or even absent; * * * the mantle lobes united, with 

siphons and a pedal, but no opisthopodial foramen; the resilium 

reinforced below by a lithodesma. 

Family VERTICORDIIDAE 

Genus VERTICORDIA (Searles Wood MS.) Sowerby 

1844. V erticordia Smverby, Mineral conchology, vol. 7, pl. 639. 

Type: Verticordia cardiiformvs Sowerby. (Pliocene 

(Coraline Crag) of Suffolk, England.) 

Sowerby uses the name Verticordia on the plate, 

though in the description he refers to it as Hippagus? 

Shell nacreous, equivalve, generally though not 

invariably small, and suborbicular. Umbones subcentral, or anterior, prmninent; prosogyrate, often 

strongly involute. Lunule false, more or less depressed. External sculpture strongly radial. Liganlent submarginal, continued to apices of umbones. 

Internal cartilage supported by lithodesma. Strong 

subumbonal cardinal generally present in the right 

valve; posterior lateral developed in one group; 

left valve comJnonly devoid of true teeth, in some 

speciinens developing a po~terior lateral, n1ore rarely 

a subumbonal cardinal. Valvular margins more or 

less modified to function as laterals. Adductor impressions small, commonly obscure. Pallial line 

simple or feebly sinuous. Inner margins frequently 

denticulated by the radiating costae. 

Verticordia has, as might be inferred, a very meager 

representation in the Tertiary of the east coast. 

The genus is characteristically a deep-water form, one 

species occurring at a depth of ahnost 1, 700 fathoms, 

whereas the Alun1 Bluff sands and marls are essentially 

shallow-water deposits. 

Only the single species has been reported from the 

Alum Bluff, and this is restricted to the C:hiuola 

formation. 

Subgenus TRIGONULINA D'Orhigny 

1845.oTrigonulina D'Orbigny, in De la Sagra, Histoire physique, 

politique et naturelle de l'lle de Cuba, Mollusques 

de Cuba, vol. 2, p. 327. 

Type: Trigonulina ornata D'Orbigny. (Recent 

from Rhode Isla.nd to the Barbados.) 

Dall 28 characterized this group as follows: 

Shell compressed laterally; ossicle long, narrow, rectangular, 

fiat; right valve as in l' erticordia, with a long lateral tooth; 

left valve as in Verticordia. 

21 Dall, W. H., op. cit., pt. 3, p. 534. 

2s Dall, W. H., Reports on the results of dredging under the supervision of 

Alexander Agassiz in the Gulf of Mexico (1877-78) and in the Caribbean ~;lea 

(1879-80): Harvard Coli. Mus. Comp. Zoology Bull., vol. 12, No. 6, p. 286, 1886. 
64 THE MOLLUSCAN FAUNA OF THE ALUM BLUFF GROUP OF FLORIDA 

Verticordia (Trigonulina) dalli Gardner, n. sp. 

Plate XV, Figures G-7 

1903. Verticordia (Trigonulina) cossmanni Dall, Wagner Fre~ 

lm;t. Sci. Trans., vol. 3, pt. G, p. 1512 (part). 

Shell highly nacreous, small, compressed, subcircular to rudely elliptical in outline, inequilaternl. 

Umbones slightly anterior, the apices moderately 

inflated, strongly prosogy--rate. Margin directly in 

front of umbones deeply excavated by false lunule. 

Escutcheon absent. .Anterior extremity broadly arcuate; posterior dorsal and lateral margins a parabolic 

curve from the umbones to the base line, which is 

approximately vertical. Surface heavily corded with 

eight subequal, abruptly elevated ribs, radiating from 

the umbones in gentle curves, convex posteriorly, the 

six anterior radials well within the anterior half of the 

shell, the posterior radial very close to the posterior 

margin and parallel to it, the remaining radial halfway 

between the posterior and the hindmost of the anterior 

series; inters paces deeply concave anteriorly and of 

approximately the same width as the radials, very 

much wider and more shallow posteriorly; entire external surface microgranular. Outer n1argins sharply 

dentate. Liga1nent deeply inset, continued to the 

apices of the umbones, doubtless reinforeed by a 

lithodesma. A single rather stout, subun1bonal ~ardinal developed in the right valve, received in the 

left valve between the dorsal margin and the thickened 

margin of the lunule, which functions as a denticle. 

Posterior margin of right valve grooved almost from 

the umbones to the base to receive the beveled margin 

of the left valve. Muscle impressions and pallial 

line obscure. Interior pearly and fluted almost to 

the umbones, in harmony with the radial sculpture. 

Dimensions: Altitude, 2.6 millimeters; latitude, 3.3 

millimeters. 

Type: U.S. Nat. Mus. No. 114673. 

Type locality: No. 2213, 1 mile below Baileys 

Ferry, Chipola River, Calhoun County, Fla. ~ 

The Jackson shell, with which this has been confounded, has much the same outline but dift'ers in the 

larger number of radials. In the V ertieordias the 

range in this character is very slight, too slight to 

permit the specific identity of a form with 8 or 9 ribs 

and one with 12 to 15. The ninth rib when present 

is introduced directly behind the anterior of the two 

isolated ribs and is usually a little less prominent 

than the others. 

Occurrence: Chipola formation, localities 7257r, 

2213P, 2564P. 

Family CUSPIDARITDAE Dall 

Genus CUSPIDARIA Nardo 

1840. Cuspidaria Nardo, Revue zoologique, p. 30. 

Type: Tell ina cuspidata Oliv!. (Recent 1n the 

Mediterranean.) 

Shell minutely pyriform in outline, feebly im~quivalve, strongly inequilateral, the anterior portion of 

the shell inflated, the posterior abruptly eonstricted 

and compressed, squarely truncate, gaping. 

The genus originated in the Mesozoic and persists 

in the reeent seas as one of the eharaeteristic deepwater forms. One species, C. lucifuga Fischer, has 

been reported from over 2,500 fathoms. 

The single valve that establishes the presenee of the 

genus in the Alum Bluff is very closely related to a 

form now living in the West Indies. 

Subgenus PLECTODON Carpenter 

1864. Plectoaon Carpenter, British Assoc. Adv. Sci. Rept. for 

1863, p. 638. 

Type: Plectodon scaber Carpenter. (Recent off the 

coast of California.) 

The group is characterized by the granular surface, 

the nearly obsolete external ligament inserted behind 

and under the beaks, and the twisting of the dorsal 

margins under the umbones to form a dental process. 

Cuspidaria (Plectodon) cf. C. granulata Dall 

1881. Neaera gramtlata Dall, Harvard Coll. Mus. Comp. 

Zoology Bull., vol. 9, No. 2, p. 111. 

1886. Leiomya (Plectodon) granulata Dall, Harvard Coli. Mus. 

Comp. Zoology Bull., vol. 12, No.6, p. 300, pl. 3, fig. 8. 

1889. Leiomya (Plectodon) granulata Dall, U. S. Nat. Mus., 

Bull. 37, p. 66, pl. 3, fig. 8. 

1903. Cuspidaria (Plectodon) granulata Dall, Wagner Free 

Inst. Sci. Trans., vol. 3, pt. 6, p. 1507. 

Dall described C. granulata in 1881 as follows: 

Shell in form somewhat like G. 0. Sars's figure of N. glacialis 

Sars, but more elongated. Sculpture of an indefinite, hardly 

perreptible, rounded ridge extending from the beak toward 

the lower angle of the rostrum, with a more defipite one extending toward the anterior margin, which it slightly angulates; 

forming tl · boundary of a sort of lunule or impressed space in 

front of the beaks; beside these there are fainter or stronger 

concentric striae or slight ridges, extending toward the margin; 

lastly, the entire surface is more or less densely covered with 

minute opaque white granules, much as in Poromya; the granulations are obscurely radiately and concentrirally arranged. 

Color dead white, beaks Jittle prominent. Teeth small, subobsolete; ventral margin rounded, anterior about the same; 

general appearance of the shell superficially much like Leda 

rninuta Fabricius. Interior very polished. Longitude, 11.0; 

altitude, 8.0; latitude, 4.0; longitude of rostrum, which is not 

smoo·ch, 3.3 millimeters. 

Off Sombrero, 54 and 72 fathoms; Barbados, 100 fathoms. 

The single valve from the Shoal River is apparently 

young and is less inflated than the Pliocene and 

Recent species. No differences can be detected in 

1narginal outline, surface sculpture, or dentition. 

However, it is to be expected that the more stable 

deeper water forms should range for longer periods 

than the men1bers of the inshore faunas. The Hecent 

C. yra.nulata has been reported from 54 fathon1s to 

118 fatho1ns, a depth sufficient to protect the fauna 

fron1 many of the abrupt environmental changes to 

which the littoral faunas are subjected. The valve 

in question probably drifted inshore and does not 

indieate an unusual depth for the fauna with which 

it is associated. 

Occurrence: Shoal River formation, loeality 5618r. 
PLATES II-XV 

65 
PLATE II 

[The specimen figured is the type unless otherwise stated.] 

FIGURE 1. Nucula chipolana Dall (p. S). Exterior of right valve; altitude, 2.75millimeters; latitude, 4.0 millimeters. (After Dall.) 

FIGURES 2-3. Nucula chipolana subsp. waltonia Gardner, n. subsp. (pp. 8-9). 

2. Exterior of right valve; altitude, 3.2 millimeters; latitude, 4.0 millimeters. 

3. Interior of right valve; altitude, 3.2 millimeters; latitude, 4.0 millimeters. 

FIGURE 4. Nucula sinaria Dall (p. 9). Interior of left valve; altitu.de, 4.0 millimeters; latitude, 4.75 millimeters. 

FIGURES 5-7. J\'ucula dasa Gardner, n. sp. (pp. 9-10). 

5. Exterior of right valve; altitude, 3.2 millimeters; latitude, 3.55 millimeters. 

6. Interior of right valve; altitude, 3.2 millimeters; latitude, 3.55 millimeters. 

7. Hinge of right valve; altitude, 3.2 millimeters; latitude, 3.55 millimeters; semidiameter, 1.5 millimeters. 

FIGURES 8-10. Nucula defuniak Gardner, n. sp. (p. 10). 

8. Exterior of right valve; altitude, 4.3 millimeters; latitude, 5.0 millimeters. 

9. Interior of right valve; altitude, 4.3 millimeters; latitude, 5.0 millimeters. 

10. Hinge of right valve; altitude, 4.3 millimeters; latitude, 5.0 millimeters; semidiameter, 1.7 millimeters. 

FIGURES 11-12. Leda basilissa Gardner, n. sp. (pp. 11-12). 

11. Exterior of left valve (cotype); altitude, 14.3 millimeters; latitude, 32.0± millimeters. 

12. Exterior of right valve (cotype); altitude, 17.0 millimeters; latitude, 38.2± millimeters. 

FIGURES 13-16. Leda acuta (Conrad) (pp. 12-13). 

13. Exterior of right valve (not the type); altitude, 3.8 millimeters; latitude, 6.8 millimeters. (After Clark.) 

14. Interior of right valve (not the type); altitude, 3.8 millimeters; latitude, 6.8 millimeters. (Mter Clark.) 

15. Exterior of left valve (not the type); altitude, 4 millimeters; latitude, 7 millimeters. (Mter Clark.) 

.16. Interior of left valve (not the type); altitude, 4 millimeters; latitude, 7 millimeters. (Mter Clark.) 

FIGURES 17-18. Leda proteracuta Gardner, n. sp. (pp. 13-14). 

17. Exterior of right valve; altitude, 2.8 millimeters; latitude, 5.0 millimeters. 

18. Interior of right valve; altitude, 2.8 millimeters; latitude, 5.0 millimeters. 

66 
U. S. GEOLOGICAL RURVEY PROFESSIONAL PAPER 142 PLATE II 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
U. S. GEOLOGICAL SURVEY PHOFESfHON AT, PAPER 142 PLATE III 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
PLATE III 

FIGURES 1-4. Leda proteracuta subsp. leila Gardner (pp. 14-15). 

1. Exterior of left valve (cotype); altitude 3.0 millimeters; latitude, 5.5 millimeters. 

2. Interior of left valve (cotype); altitude, 3.0 millimeters; latitude, 5.5 millimeters. 

3. Exterior of right valve (cotype); altitude, 3.0 millimeters; latitude, 6.0 millimeters. 

4. Hinge of left valve (cotype; altitude, 3.0 millimeters; latitude, 5.5 millimeters; semidiameter, 1.45 millimeters. 

FIGURE 5. Leda proteracuta subsp. dystakta (p. 14). Exterior of left valve; altitude, 3.5 millimeters; latitude, 6.4 millimeters. 

FIGURE 6. Leda proteracuta subsp. diamesa Gardner (p. 15). Exterior of left valve; altitude, 3.7 millimeters; latitude, 6.5 millimeters. 

FIGURES 7- 8. Leda leptalea Gardner, n. sp. (p. 16). 

7. Exterior of left valve; altitude, 3.5 millimeters; latitude, 5.7 millimeters. 

8. Interior of left valve; altitude, 3.5 millimeters; latitude, 5.7 millimeters. 

FIGURES 9-10. Leda polychoa Gardner, n. sp. (pp. 17- 18). · 

9. Exterior of right valve; altitude, 3.5 millimeters; latitude, 6.1 millimeters. 

10. Dorsal view of double valves; altitude, 3.5 millimeters; latitude, 6.1 millimeters; diameter, 2.5 millimeters. 

FIGURES 11-12. L eda polychoa subsp. defuniak Gardner, n. subsp. (pp. 18-19). 

11. Exterior of left valve (not the type); altitude, 3.4 millimeters; latitude, 5.5 millimeters. 

12. Exterior of right valve; altitude, 4.0 millimeters; latitude, 7.5 millimeters. 

FIGURES 13- 14. Leda leiorhyncha Gardner, n. sp. (p. 19). 

13. Exterior of left valve; altitude, 3.5 millimeters; latitude, 6.0 millimeters. 

14. Interior of left valve; altitude, 3.5 millimeters; latitude, 6.0 millimeters. 

FIGURES 15-17. Leda canonica Dall (pp. 16-17). 

15. Exterior of left valve (not the type); altitude, 2.9 millimeters; latitude, 5.0 millimeters. 

16. Exterior of right valve; altitude, 1.4 millimeters; latitucle, 2.5 millimeters. 

17. Exterior of right valve (not the type); altitude, 3.1 millimeters; latitude, 5.2 millimeters. 

FIGURE 18. Leda canonica subsp. meiopykna Gardner, n . sllbsp. (p. 17). Exterior of right valve; altitude, 3.0 millimeters; latitude, 

5.6 millimeters. 

67 
PLATE IV 

FIGURE 1. Trinacria meekii Dall (p. 22). Interior of right valve; altitude, 3.2 millimeters; latitude, 5.5 millimeters. (After 

Dall.) 

FIGURES 2-5. Trinacria meekii subsp. parameekii Gardner, n. subsp. (p. 22). 

2. Exterior of left valve (eotype); altitude, 2.7 millimeters; latitude, 4.6 millimeters. 

3. Interior of left valve (eotype); altitude, 2.7 millimeters; latitude, 4.6 millimeters. 

4. Interior of right valve (eotype); altitude, 2.6 millimeters; latitude, 4.5 millimeters. 

5. Exterior of right valve (eotype); altitude, 2.6 millimeters; latitude, 4.5 millimeters. 

FIGurm 6. Leda dodona Dall (p. 20). Exterior of left valve; altitude, 5.0 millimeters; latitude, 9.0 millimeters. (After Dall.) 

FIGURE 7. Yoldia frater Dall (pp. 20-21). Exterior of left valve; altitude, 8.0 millimeters; latitude, 19.0 millimeters. (After 

Dall.) 

FIGURES 8- 12. Yoldia soror Gardner, n. sp. (p. 21). 

8. Exterior of left valve; altitude, 5.6 millimeters; latitude, 11.5 millimeters. 

9. Exterior of right valve; altitude, 5.6 millimeters; latitude, 11.5 millimeters. 

tO. Interior of left valve; altitude, 5.6 millimeters; latitude, 11.5 millimeters. 

11. Interior of right valve; altitude, 5.6 millimeters; latitude, 11.5 millimeters. 

12. Hinge of left valve; altitude, 5.6 millimeters; latitude, 11.5 millimeters; diameter, 4.0 millimeters. 

FIGURES 13-15. Leda diphya Gardner, n. sp. (pp. 19-20). 

13. Exterior of left valve; altitude, 4.7 millimeters; latitude, 8.1 millimeters. 

14. Interior of left valve; altitucle, 4.7 millimeters; latitude, 8.1 millimeters. 

15. Exterior of juvenile left valve (not the type). 

68 
U. S. GEOI, OGICAT. SURVEY PROFESSIONAl, PAPER 142 PLATE IV 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 PLATE V 

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PRIOI'\ODES:v!ACEA OF THE ALU:\I BLUFF GROUP 
PLATE V 

FIGURES 1-4. Barbatia adamsi (Shuttleworth) DaiJ (p. 28) . 

1. Exterior of left valve (nut the type); altitude, 6.5 millimeters; latitude, 11.5 millimeters. 

2. Interior of left valve (not the type); altitude, 6.5 millimeters; latitude, 11.5 millimeters. 

3. Exterior of right valve (not the type); altitude, 6.5 millimeters; latitude, 11.5 millimeters. 

4. Interior of right valve (not the type); altitude, 6.5 millimeters; latitude, 11.5 millimeters. 

FIGURE 5. A1·ca paratina Dall (p. 25). Exterior of left valve ; altitude, 10.0 millimeters; latitude, 28.0 millimeters. (After DaiJ.) 

FIGURE 6. Barbalia phalacra Dall (pp. 2G- 27). Interior of left valve; altitude, 11.0 millimeters; latitude, 23.5 miiJimeters. (After 

Dall.) 

FI<:t·nE 7. Diluvarca latidentata (DaiJ) (pp. 28-29). Exterior of left valve; altitude, 11.0 millimeters; latitude, 18.0 millimeters. 

(After Dall.) 

FIGURES 8-9. Diluvarca mikkula Gardner, n. sp. (p. 29). 

8. Exterior of left vah·e; altitude, 3.5 millimeters; latitude, 6.0 millimeters. 

9. Dorsal view of double valves; altitude, 3.5 millimeters; latitude, 6.0 millimeters; diameter, 3.2 millimeters. 

FIGURE 10. Diluvarca initiator (Dall) (p. 34). Exterior of left valve; altitude, 4.7 millimeters; latitude, 5.0 millimeters. (After 

Dall.) 

FIGUHE 11. Diluvarca accom]JSa (Dall) (p. 30). Exterior of right valve; altitude, 10.5 millimeters; latitude, 20.0 millimeters. 

(After Dall.) 

FIGURE 12. Diluvarca hypomela (Dall) (pp. 29-30). Exterior of left valve; altitude, 25.0 millimeters; latitude, 50.0 millimeters. 

(After Dall.) 

FIGURE 13. Diluvarca stamina/a (Dall) (pp. 30-31). Exterior of left valve; altitude, 37.0 millimeters; latitude, 47.0 millimeters. 

(After Dall.) 

FIGURES 14-15a. Dil1tvarca dodona (Dall) (p. 30) . 

14. Dorsal view of double valves; altitude, 28.0 miiJimeters; latiturle, 40.0 millimeters; diameter, 30.0 millimeters. (After 

Dall.) 

15. Exterior of left valve; altitude, 28.0 millimeters; latitude, 40.0 millimeters. (After DaiJ.) 

15a. Detail of sculpture. (After Dall.) 

69 
PLATE VI 

FIGURES 1-2. Diluvarca santarosana (DalJ) (p. 31). 

1. Exterior of left valve; altitude, 28.0 millimeters; latitude, 36.5 millimeters. (After Dall.) 

2. Dorsal view of double valves; altitude, 28.0 millimeters; latitude, 36.5 millimeters; diameter, 28.0 millimeters. (After Dall.) 

FIGURES 3-6. Diluvarca waltonia Gardner, n. sp. (pp. 32-33). 

3. Interior of right valve (not the type); altitude, 33.0 millimeters; latitude, 35.0 millimeters. (After Dall.) 

4. Anterior view of double valves; altitude, 32.5 millimeters; latitude, 33.0 millimeters; diameter, 36.0 millimeters. 

5. Exterior of left valve; altitude, 32.5 millimeters; latitude, 33.0 millimeters. 

6. Exterior of right valve; altitude, 32.5 millimeters; latitude, 33.0 millimeters. 

FIGURES 7-10. Diluvarca cardioides Gardner, n. sp. (pp. 34-35). 

7. Exterior of right valve (cotype); altitude, 5.0 millimeters; latitude, 5.8 millimeters. 

8. Interior of right valve (cotype); altitude, 5.0 millimeters; latitude, 5.8 millimeters. 

9. Exterior of left valve (cotype); altitude, 7.7 millimeters; latitude, 9.0 millimeters. 

10. Interior of left valve (cotype); altitude, 7. 7 millimeters; latitude, 9.0 millimeters. · 

70 
U. S. GEOLOGICAL SUHVEY PHOFESSIONAL PAPER H2 PLATE VI 

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l'IUONODESMACEA OF THE ALUU BLUFF GROUP 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 PLATE Vll 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
PLATE VII 

FIGURES 1-2. Dil-uvarca santarosana subsp. geraetera Gardner (pp. 31-32). 

1. Exterior of left valve (cotype); altitude. 36.5 millimeters; latitude, 39.0 millimeters. 

2. Exterior of right valve (cotype); altitude, 35.0 millimeters; latitude, 37.5 millimeters. 

71 
PLATE VIII 

FrGURES 1-2. Dilul!arc"a strebla Gardner, n. sp. (pp. 33--34). 

L Exterior of right valve; altitude, 27.0 millimeters; latitude, 41.0 millimeters. 

2. Dorsal view of double valves; altitude, 27.0 millimeters; latitude, 41.0 millimeters; diameter, 26.0 millimeters. 

FIGURES 3-8. Glycymeris subovata (Say) (pp. 35- 36). 

3. Exterior of right valve (not the type); altitude>, 55.0 millimeters; latitude, 58.0 millimeters. 

4. Interior of left valve (not the type); altitude, 55.0 millimeters; latitude, 59.0 millimeters. 

5- 8. Hinges showing progressive encroachment of the cardinal area upon the dental arch (not the type). 

72 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 !'LATE VIII 

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PniONODESMACEA OF THE ALUM BLUFF GROUP 
U. S. GEOLOGICAL SURVEY 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 

PROFESSIONAL PAPER 142 PLATE IX 

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.~ 

,;;.·\···'"·;1,;·~-- . • ' ' 

., 

,., ' . } 

·~,L~! 

12 

4 
PLATE IX 

I 

FwuaEs 1- 2. Glycymeris drymanos Gardner, n. sp. (p. 36). 

1. Exterior of left valve (cotype); altitude, 38.2 millimeters; latitude, 37.5 millimeters. 

2. Interior of right valve (cotype); altitude, 38.5 millimeters; latitude, 38.5 millimeters. 

·FIGURES 3-4. Glycymeris drymanos subsp. grapta Gardner, n. subsp. (p. 37). 

3. Exterior of right valve (cotype); altitude, 37.0 millimeters; latitude, 37.6 millimeters. 

4. Exterior of left valve (cotype); altitude, 36.5 millimeters; latitude, 36.5 millimeters. 

FIGURES 5-8. Glycymeris waltonensis Gardner, n. sp. (pp. 37-38). 

5. Anterior view of double valves; altitude, 33.9 millimeters; latitude, 35.1 millimeters; diameter, 20.6 millimeters. 

6. Exterior of left valve; altitude, 33.9 millimeters; latitude, 35.1 millimeters. 

7. Exterior of left valve (not the type); altitude, 33.0 millimeters; latitude, 35.5 millimeters. 

8. Interior of right valve (not the type); altitude, 33.0 millimeters; latitude, 35.5 millimeters. 

FIGURES 9-12. Glycymeris pectinata (Gmelin) (p. 38). 

9. Exterior of right valve (not the type); altitude, 12.5 millimeters; latitude, 12.5 millimeters. 

10. Interior of right valve (not the type); altitude, 12.5 millimeters; latitude, 12.5 millimeters. 

11. Exterior of left valve (not the type); altitude, 15.5 millimeters; latitude, 15.5 millimeters. 

12. Interior of left valve (not the type); altitude, 15.5 millimeters; latitude, 15.5 millimeters. 

73 
PLATE X FIGURES 1- 2. Ostrea rugifera Dall (p. 41). 

1. Interior of left valve (cotype); altitude, 58.0 millimeters; latitude, 38.0 millimeters. 

2. Exterior of right valve of another individual (cotype); altitude, 61.5 millimeters; latitude, 37.0 millimeters. 

FIGURES 3-4. Ostrea pauciplicata Dall (p. 41). 

3. Exterior of left valve (cotype); altitude, 55.0 millimeters; latitude, 37.0 millimeters. 

4. Exterior of right valve of another individual (cotype); altitude, 47.0 millimeters; latitude, 28.0 millimeters. 

FIGURES 5-6. Ostrea podagrina Dall (pp. 42--43). 

5. Exterior of left valve; altitude, 100.0 millimeters; latitude, 110.0 millimeters. (After Dall.) 

6. Interior of left valve; altitude, 100.0 millimeters; latitude, 110.0 millimeters. (After Dall.) 

74 
U. S. GEOLOCICAJ, SUUVEY PROFESSIONAL PAPER 142 PLATE X 

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PRIONODESMACEA OF TilE ALUM BLUl?J.<' GROUP 
U. S. GEOLOGICAL SURVEY PROFESSIONAT, PAPER 142 PLATE :KI 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
PLATE XI 

FIGURES 1-2. Chlamys (Lyropecten) acanikos Gardner, n. sp. (p. 46). 

1. Exterior of right valve (not the type); altitude, 26.0 millimeters; latitude, 23.0 millimeters. 

2. Exterior of left valve; altitude, 36.0 millimeters; latitude, 35.0 millimeters. 

FIGURES 3-4. Ostrea normal is Dall (p. 43). 

3. Exterior of right valve (cotype); altitude, 95.0 millimeters; latitude, 55.0 millimeters. 

4. Exterior of left valve (cotype); altitude, 100.0 millimeters; latitude (exclusive of projecting lamellae) 50.0 millimeters. 

75 
PLATE XII 

FIGURE 1. Pecten (Pecten) burnsii Dall (pp. 44--45). Exterior of right valve; altitude, 18.0 millimeters; latitude, 19.0 millimeters; 

diameter, 6.0 millimeters. (After Dall.) 

FIGURE 2. Chlamys (Chlamys) chipolanus Dall (p. 47). Exterior of left valve; altitude, 25.0 millimeters; latitude, 25.0 millimeters. 

(After Dall.) 

FIGURES 3-4. Chlamys (Nodipecten) condylomatus Dall (pp. 46-47). 

3. Exterior of left valve; altitude, 24.0 millimeters; latitude, 23.0 millimeters. (After Dall.) 

4. Profile of same. (After Dall.) 

FIGURES 5--6. Chlamys (Plagioctenium) nicholsi Gardner, n. sp. (p. 48). 

5. Exterior of right valve (cotype); altitude, 20.6 millimeters; latitude, 21.2 millimeters. 

6. Exterior of left valve of another individual (cotype); altitude, 25.0 millimeters; latitude, 25.5 millimeters. 

FIGURE 7. Chlamys (Lyropecten) sayan us Dall (pp. 45-46). Exterior of right valve; altitude, 120.0 millimeters; latitude, 135.0 

millimeters. 

FIGURES 8-9. Chlamys (Chlamys) alumensis Dall (pp. 47-48). 

8. Exterior of left valve (cotype); altitude, 8.5 millimeters; latitude, 7.8 millimeters. (After Dall. 

9. Exterior of right valve of another individual (cotype); altitude, 8.0 millimeters; latitude, 7.5 millimeters. (After Dall.) 

FIGURES 10-12. Pseudamussium defuniak Gardner, n. sp. (p. 49). 

10. Exterior of left valve (cotype); altitude, 4.6 millimeters; latitude, 4.6 ± millimeters. 

11. Exterior of right valve of another individual (cotype); altitude, 3.8 millimeters; latitude, 3.75 millimeters. 

12. Hinge area of left valve, X 10. 

FIGURES 13- 14. Pseudamussium diktuotum Gardner, n. sp. (pp. 49-50). 

13. Exterior of right valve (cotype); altitude, 3.8 millimeters; latitude, 4.0 millimeters. 

14. Exterior of left valve of another individual (cotype); altitude, 4.2 millimeters; latitude, 4.5 millimeters. 

76 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 PLATF. XII 

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PRIONODESMACEA OF THE ALUM BLUFF GHOUP 
U. S. GEOLOGICAl, SURVEY PROFESSI ONAL PAPER 142 PLATE XIII 

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PRIONODESMACEA OF THE ALUM BLUFI' GROUP 
PLATE XIII 

FIGURES 1-3. Plicatula densata Conrad (pp. 51-52). 

1. Exterior of right valve (not the type; altitude, 28.0 millimeters; latitude, 24.0 millimeters. (After Glenn.) 

2. Interior of right valve .(not the type); altitude, 28.0 millimeters; latitude, 24.0 millimeters. (After Glenn.) 

3. Exterior of left valve (not the type); altitude, 30.0 millimeters; latitude, 26.0 millimeters. (After Glenn.) 

FIGURE 4. Lima carolinensis Dall (p. 53). Exterior of right valve; altitude, 16.0 millimeters; latitude, 12.0 millimeters. (After 

Dall.) 

FIGURE 5. Anomia suwanneensis Gardner, n. sp. (pp. 54- 55). Exterior of left valve; altitude, 45.0± millimeters; latitude, 52.0 

millimeters. 

FIGURES 6-7. Anomia glypta Gardner, n. sp. (pp. 53-54). 

6. Interior of left valve (not the type); altitude, 27.0 millimeters; latitude, 29.0 millimeters. 

7. Exterior of left valve; altitude, 41.0 millimeters; latitude, 46.0± millimeters. 

FIGURE 8. Anomia microgram mala Dall (p. 54). Interior of left valve; altitude, 17.0 millimeters; latitude, 25.0 millimeters. (After 

Dall.) 

FIGURE 9. Pododesmus scopelus Dall (p. 55). Interior of right valve; altitude, 44.0 millimeters; latitude, 58.0 millimeters. (After 

Dall.) 

FIGURE 10. Anomia jloridana Dall (p. 54). Interior of left valve; altitude, 29.0 millimeters; latitude, 21.0 millimeters. (After 

Dall.) 

FIGURE 11. Plicatula lepidota Gardner, n. sp. (p. 52). Exterior of left valve; altitude, 29.5 millimeters; latitude, 30.0 millimeters. 

FIGURE 12. Pododesmus rudis Broderip (p. 55). Exterior of left valve (not the type); altitude, 40.0 millimeters; latitude, 36.0 

millimeters. 

77 
PLATE XIV 

FIGURES 1-5. Carolia (Wakullina) jloridana Dall (pp. 56- 57). 

1. Interior of left valve (cotype); altitude, 130.0± millimeters; latitude, 122.0± millimeters. (After Dall.) 

2. Profile of hinge of right valve showing scar of foramen and profile of chondrophore (cotype); natural size. (After Dall.) 

3. View of same specimen from above (cotype); natural size. (After Dall.) 

4. Cardinal area of double valves (cotype). (After Dall. p. 57) 

5. Exterior of left valve of the same individual (cotype); altitude, 110.0 millimeters; latitude, 110.0 millimeters. (After 

Dall.) 

FIGURES 6--7. Mytilus pandionis Dall (p. 57). 

6. Internal cast of right valve; altitude, 122.0 millimeters; latitude, 60.0 millimeters; diameter 36.0 millimeters. (After 

Dall.) 

7. Profile of same cast. (After Dall.) 

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U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 PLATE XI\" 

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PRIONODESMACEA OF THE ALUM BLUFF GROUP 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 142 PT,ATE XV 

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PRIONODESMACEA AND ANOMALODESMACEA OF THE ALUM BLUFF GROUP 
PLATE XV 

FIGURES 1-3. Julia jloridana Dall (p. 61). 

1. Interior of left valve (cotype); altitude, 2.7 millimeters; latitude, 3.5 millimeters. (After Dall.) 

2. Exterior of right valve (cotype); altitude, 2. 7 millimeters; latitude, 3. 7 millimeters. (After Dall.) 

3. Interior of right valve (cotype); altitude, 2. 7 millimeters; latitude, 3.5 millimeters. (After Dall.) 

FIGURE 4. Modiolus (Brachidontes) curtulus Dall (p. 58). Exterior of right valve; altitude, 12.0 millimeters; latitude, 7.0 millimeters. 

FIGURE 5. Modiolus (Brachidontes) grammatus Dall (p. 58). Exterior of left valve; altitude, 20.0 millimeters. (After Dall.) 

FIGURES &-7. Verticordia dalli Gardner, n. sp. (p. 64). 

6. Interior of right valve; altitude, 2.6 millimeters; latitude, 3.3 millimeters. 

7. Exterior of right valve; altitude, 2.6 millimeters; latitude, 3.3 millimeters. 

FIGURE 8. Pandora (Kennerleyia) dodona Dall (p. 63). Exterior of left valve; altitude, 5.2 millimeters; latitude, 12.5 millimeters. 

(After Dall.) 

FIGURE 9. Crenella minuscula Dall (p. 60). Exterior of left valve; altitude, 1.75 millimeters; latitude, 1.25 millimeters. (After 

Dall.) , 

FIGURE 10. Lithophaga oryzoides Gardner, n. sp. (p. 60). Exterior of left valve; altitude, 5.7 millimeters; latitude, 2.6 millimeters. 

FIGURES 11-13. Periploma discus Gardner, n. sp. (pp. 61-62). 

11. Portion of hinge of right valve showing chondrophore (paratype); X2. 

12. Exterior of same specimen (paratype); X 2. 

13. Cast of interior with adhering fragments of nacre; altitude, 67.0 ±millimeters; latitude, 70.0 ±millimeters. 

79 

INDEX 

A P• 

A car Gray __ ---------------------------------------------------------------- 26,27 Adelosiphonia_______________ ___ ___ _ _ _ _ _ _ _ __ _ _ _ _ __ _ __ _ ___ ____ _ _ _ _ _ _ _ _ _ _ __ _ __ _ 62 

Aequipecten. See Pecten. 

Aldrich, T. II., cited._------------------------------------------------------

Alum Bluff group, earlier work on.------------------------------------------ 1-2 

map showing fossiliferous localities of----------------------------------- Pl. I 

nature and fossils oL ---------------------------------------------------- 1 

physical changes in time oL .. ------------------------------------------- 2 

Amusium Bolten ..................... ------ __ . __ .......... __ ... __ --------___ 60 

Amusium s. s. (see Pecten).------------------------------------------------- 50 

papyraceum Gabb ___ . ___ .. _ ... _ .. _ .................•... _ .......•••.. ___ 50 

precursor Dan ......... ____ ...... _ .. __________ ... __________ ... ------------ 44, 50 

Anadam aresta Dan ............ _________________ ---------------------------- 29,33 

Anatinacea ................................. _ ....... _ ................. ------- 61 

Anomalodesmacea Dall. ____ ------------ ___ ------------------.............•. 61 

Anomia (Linnaeus) M tiller •.•.............. __ . __ .. _ .... _ ..... __ . __ ._....... 53 

aculeata (Gmelin) ......•......................... _________ .............. 54, 55 

ephippium Linnaeus. ............. ... ............ .................•.•... 53 

cphiiJPOides Gabb .............................. _ ...... ____ ... __ --------- 54 floridana Dan __________________________________________________ 53, 54, Pl. .A III 

glypta Gardner, n. SP------------------------------------------ 63-64, Pl. XIII 

microgrammata DaJL _________________________________________ 53, 54, Pl. XIII 

ruffini Conrad .......... __________________________ .. __________ ---------.. 54 

simplex D'Orbigny .................................................... _. 54 

suwanneensis Gardner, n. sp ................................ 53,54-55, Pl. XIH 

Anomiidae .............. __ ...................... _ ............ __ ............. 53-57 

Area (Linnaeus) Lamarck ................................. __ ................ 22 

acompsa Dan ............... _____________________________ ------- __ 23, 30, Pl. V 

actinophora DalL ________________________________________ --------------- 33 

adamsi Dall _________________________________________________ 22, 23, 27, 28, Pl. V 

conradiana Dall. ------- _________ ... ______ ...... -------------------- 28 

alternata Reeve_--------- ______ ._ ..... _ ..... ______ ._ .. ___ --------------- 26 

barbadensis D'Orbigny __ .. ______________________ ... -------------------- 24 

barbata Linnaeus. _ ------- _______________ ------------------------------- 25 

candida Gmelin ..•.... _ -- ____ ... _. __ . __ .. _. _ .. ___ ..... ------------------ 26 

cartlioides Gardner, n. sp _____________ -------------------------- 23,34-35, Pl. VI 

chiriquiensis Gabb __________________________________ -------------------- 31 

eli sea Dan _____________________________________________ ------------------ 32,33 

coelata Conrad.---------- _____________________________________ .. ________ 28 

cor-cupidonis Maury____________________________________________________ 34 

diluvii Lamarck.------------------------ _______________________ -------- 28 

dodona Dan .. _------------- ______________________________________ 23, 30, PI. V 

domingensis Lamarck _____________ . ____________________________ --------- 27 

donacitormis Reeve .. --------------....... _. __ . ___ . ________ . __ ._ .... ____ 27 

gradata Broderip and SowerbY------------------------------------------ 27 

benikeni Maury----------------...... --_--_ .. _ .. __ ...... _ .. _____________ 30 

hypomela Da!L ............ ___________________________________ 23,29-30, Pl. V 

imbrieata Bruguiere ............. _______ .. _____________________________ .. 24 

incongrua Say------------------......... __ ..... _........................ 34 

inequivalvis Bruguiere ..... ___ ...... _ ...... _ ..... __ ...............• _____ 28 

initiator Dall ____________________________________________________ 23, 34, 35, Pl.V 

lactea C. B. Adams..................................................... 28 

latidentata Dan ________________________________________________ 23,28-29, Pl. V 

lienosa Say .. _ ...•........... _ ............ ---.........•.•• -------------- 29 

listeri? Philippi__ _____________________________________ ------------------- 24 

marylandica Conrad _________________ ~ ________________ ---------------- 23, 26,27 

mikkula Gardner, n SP------------------------------------------ 23,29,30, PI. V 

noae Linnaeus ____ ---------.. __ ................... ----------------------- 22, 23 

nucleus Linnaeus ........ ___ . _ .... _ ............. ---------------------- ___ 8 

occidentalis Philippi..------------------.------------------------- 22,23-24, 25 paratina Dan ________________________________________________ 23, 24, 25, PI. V 

phalacra DalL .............. ______________________ -------------- 23,26-27, Pl. V 

quadrilatera Lamarck .••....................... _ .... -------------------- 27 

reticulata Gmelin.-. -------------------............. _ ---------------- 22, 23, 27 

rostrata Gmelin .. ------------ _ --.... --...... _ ........ ------------------- 10 

santarosana Dall ... -------------------- ___ -__________ ---------- 23, 31, 33, Pl. VI 

geraetera Gardner, n. subsp. ____________________________ 23,31-32,33,34, Pl.VII 

staminata DaiL _____________________________________________ 23, ~31, 33, Pl.V 

staminea Say __ --------------------------------.. ______ --------------- 31, 32, 33 

strebla Gardner, n. sp _______________________________________ 23,33-34, Pl. VIII 

subprotracta Ileilprin .. ---------------- _______ ... ___ -------------------- 25 

umbonata Lamarck.---------------------------------------------- 22, 23,24-25 

waltonia Gardner, n. sp .. ----------------------------------- 23,31,32-33, Pl.VI 

yaquensis Maury __ ----------------------------------------------------- 25 

/ 

Page Arcidae ____ ------ ________ -~ ____________ • ______ • ___________ • ___ ---. ___ ------- 22-38 

Atrina Gray------------------ ________ ------------_--- ______ ----------------- 39 

argentea (Conrad)_ ...... _____ ...... ______ ....... ___________ ------------- 39 

chipolana DalL ______ -------- ___ . ____ .. ______ --------------------------- 39 

B 

Barbatia Gray (see Area) _______ .. ---- ___ ------------ ____ ------------------- 23, 25 

adamsi Dan ____________________________________________________ 23, 27, 28, Pl. V 

bonaczyi Gabb _ ....... _____ .. ____ . ___ .. __ ... _. _ .. _. ___ . _____ .... ______ . 24 

carolinensis Conrad. __ . ____ ... _ •.. _ .. ____ ... _----- _______________ ------- 26 

mississippiensis Conrad _____________ ....... ____ .. __ ..•..... --•.. ___ .____ 26 

phalacra DalL ...... -------------------------------------- 23, 26-27, Pl. V 

(A car) reticulata Gmelin. ----------------------------------------------- 23,27 

(Fossularca) adamsi (Shuttleworth MS.) DulL. _______________ 23, 27, 28, Pl. V 

(Plagiarca) marylandica. Conrad .... ---------------------------------- 23, 26,27 Botula l\forch .. _____ . __ . __ .... _________________ . _. ____ ... ___ . ________ . __ . __ _ 58 

Brachidontes Swainson. __ ---------------- ___ ------------------------------- 58 

Brown, Thomas, cited .. _____ ------------- __ -------------------------------- 59 

Byssoarca lithodomus Sower by ____ . __ ._._. _____ ..... _ ...... __ .... _ ... __ .____ 26 

c 

Calloarca Gray------------------....... ___ ... _ ... _. ____ ----------.. ___ .----- 26 

Carolia Cantraine. ____ .... __ ... _ .. _. _________ . __ . __ .. ____ .......... ___ . __ . __ 56, .57 

placunoides Cantraine ..... ________ .... _ ... _. ____ .. _ ... _ .. ___ . ___ . _ ... _ .. 56 

('Vakullina) fl.oridana Dull ____________________________________ 56-57, Pl. XIV 

Chipola marl member, fauna of.._------- _______ -------- ____ ---------------- 1 

Chlamys Bolten, s.l. (see Pecten)---------------------------------------- 44,45-48 

Chlamys s. s ___ ... ____ ... __ ..... _ ------ ____ .. __ .. _____ .. _ ... --------------. _. 47, 48 

inaequalis acutipictus Woodring __ ----------- ___ ------------------------ 47 

jeffersonius edgecombensis Conrad-------------------------------------- 45 

madisonius Say _____ . _. __ .... _- ... ___ .... _. __ . __ .. ---------.------------ 45, 46 

(Chlamys) alumensis DulL _________________________________ 44,47-48, Pl. XII 

chipolanus Dan _______________________________________ 44, 46, 47, 48, Pl. XII 

sp ___ .... ________ . __ . __ . ___________ .. __ . __ ..... _________ ------------- 44, 47 

(Lyropecten) acanikos Gardner, n. SP------------------------- 44,46,47, Pl. XI 

sayanus Dall ______________________________________ -i3,44,45-46,48, Pl. XII 

(Nodipecten) condylomatus DalL --------------------------- 44,46-47, Pl. XII 

(Plagioctenium) nicholsi Gardner, n. sp .. _ --------------------- 44, 48, Pl. XII 

Conrad, T. A., cited. _________ --------- ________________ 12, 26, 28, 38, 42, 45, 51-52,57 

Cossman, A. E. M., cited·-------------------------------------------------- '1.7 

Couthouy, J.P., cited .... --------------------------------------------------- 62 

Crenena Brown _______ ----------------------- ________ ----------------------- 59--60 

divaricata D'Orbigny _ -------------- _____ ------ ___ ------------- ___ ------ 60 

minuscula DalL ....... --------------------------------------- ____ 60, Pl. XV 

sericea Brown .... ------------------------------------------------------ 59 

Cunearca DalL _ ---------------- _ ------------------------------------------- 34 

Cuspidaria Nardo ..... __ . ____ ...... --_--... ---.-.-... --_ ... -.-....... _...... 64 

lucifuga Fischer. ____________ ------ _______ ------------------------------- 64 

(Plectodon) cf. C. granulata DaiL______________________________________ 64 

Cuspidariidae DalL. _ ...... ---------.. --.-.-.... --.-.. ---.-.-.. ----.•... ---- 64 

D 

Dall, W. II., cited-----------------------------------------------------·-- 8, 9, 14, 

16, 20, 22, 25, 26, 28, 29, 30, 31, 34, 39, 40, 41, 42, 43,44, 45, 

46, 47, 48, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61,62-63, 64 

Dall, W. H., and Simpson, G. B., cited .. ----------------------------------- 59 

Diluvarca (see Area and Scapharca). _ --------------------------------------- 28 

E 

Ephippium papyraceum (Lamarck) _______ ---------------------------------_ 56 

Eusiphonia .... ---------.-------.•. ----------------------------.•. --------.. 61 

F 

Florida, northern and western, map oL------------------------------------- 2 

Fossularca Cossman·----------------------------..... _ ... _ .. __ ._-----.______ 27 

G 

Glycymeris Da Costa_------------------------------------------------------ 35 

americana De France·------------------------------------------------ 35, 37,38 

drymanos Gardner, n. sp. ---------------------------------- 2, 35, 36, 37, Pl. IX 

grapta Gardner, n. subsp ______________________________ 35, 36, 87, 38, Pl. IX 

orbicularis Da Costa __________________ .. _ .. __ .-... _. __ .. _---------------- 35 
II INDEX 

Page 

Glycymeris pectinata (Gmelin) __ -· ---------------------------------- 35, 38, Pl. IX 

plagia Dall ______________________________________________ ------------- _ __ 37 

subovata Say ________________________________________ ~- _____ 35-36, 37, Pl. VIII 

waltonensis Gardner, n. sp_ ----------------------------- 2, 35, 36,37-38, Pl. IX 

sp. cf. d:. americana De France.----------------------------------------- 38 

Gmelin, J. F., cited __ ----------------- ____________________________ ---------- 27,38 

Gray, J. E., cited------------------------------------------------------------ 25 

J Julia Gould __ ------------------------- _____________ ------------------------- 60 

exquisita Gould ___ -------------------------- ___ ------------------------- 60 

floridana Dan ___________________________________________________ 60, 61, Pl. XV 

Juliidae Dan _________________________________________________ --------------- 60-61 

K Kennerleyia Carpenter _______ ------_________________________________________ 63 

filosa Carpenter_________________________________________________________ 63 

L 

Leda Schumacher_--------------- _______ ------ ___ ------ _________ -------_____ 10 

acuta (Conrad) ___ --------------------------------------- 11, 12-13, 16, 19, Pl. II 

basilissa Gardner, n. sp _______________________________________ : 10, 11-12,-Pl. II 

calatabianensis Seguenza _______________________________ ---------------- _ 16 

canonica Dan ___________________________________________ 10, 11, 14, 16, 17, Pl. III 

meiopykna Gardner, n. subsp __________________________ 11, 13, 16, 17, Pl. III 

diphya Gardner, n. SP-------------------------------- 10, 11, 13, 14,19-20, Pl. IV 

dodona Dall __ -------------- __________________________________ 11, 13, 20, Pl. IV 

lciorhyncba Gardner, n. sp ____________________________________ 11, 14, 19, Pl. III 

leptalea Gardner, n. sp __________________________________ 11, 13, 15, 16, 17, Pl. III 

linifera var. chipolana Dall_____ ___ __ _ ___ __ _ _ __ ________ ____ __ _________ ___ 14 

min uta Fabricius ___________________________________________ -----------__ 64 

pernula (Muller)----------------- _____________________ ------------------ 10 

pharcida Dall _______________ ------------------- _____ --------------------- 10, 12 

polycboa Gardner, n. SP-------------------------------- 11, 14, 17-18,19, Pl. III 

defuniak Gardner, n. subsp ---------------------- 11, 14,18-19,19, Pl. III 

proteracuta Gardner, n.sp ________________ 11, 12, 13-14, 14, 15, 16, 17, 18, 19, Pl.II 

diamesa Gardner, n. subsp --------------------- 11, 13, 14, 15, 16, 20, Pl. III 

dystakta Gardner, n. subsp ________________________ 11, 13, 14, 15, 20, Pl. III 

lcita Gardner, n. subsp _____________ ----------- _____ 11, 13, 14-15, 19, Pl. III 

unca ________ ----------------- ___ ------------ _ ----------------------- 12 Ledidae _____________________________________________________________________ 1Q-21 

Lima (Bruguiere) Cuvicr ____________________________________________________ 52-53 

Lima, s. s __ ---------------- _________________ . ______________ ------ ______ _____ 52 

hians (Gmelin) __________ ------------- ____ . _______ ------------- _ --------- 53 

papyria Conrad ___________________________________________________ ------ 53 

(Mantellum) carolinensis Dan ____________________________________ 53, Pl. XIII 

papyria _____________________ -------- ________ --------------------------- 53 

Limidae D'Orbigny ------ ____________ --------------------------------------- 52-53 

Limopsidae ____________________________ -- ___________________________________ 21-22 

Litharca Gray----------------------- _____________________ -------------______ 26 

Lithophaga Bolten__________________________________________________________ 60 

niger D'Orbigny __ ------------------------------------------------------ 60 

oryzoides Gardner, n. sp ________________ -------- ___________________ 60, Pl. XV 

Localities, list of_ _______ ------ ____________ ------_____________________________ 3-4 

Lyropecten Conrad (see Pecten) ________ ----_________________________________ 45 

estrellanus Conrad ___ -------------------------__________________________ 45 

M 

Mantellum Bolten ___ ----------------------------- ______ -------------------- 53 

Maury, C. J., cited__________________________________________________________ 39 

Melina (see Pedalion) ________________ ---------- ___ __ _ __ _ _ _____ ___ __ _ __ _ ___ __ 39 

Modiola cinnamomea Lamarck__ ___ __ _ __ _ _ __ _ __ _ __ _ _ _ __ _ _ _ _ ___ _ __ ___ __ _ __ __ 58 

cretacea Conrad_________________________________________________________ 58 

sulcata Lamarck _________________ --_____________________________________ 58 

Modiolaria Beck--- __________________ --- _____________________________ =______ 59 

lateralis __________________________ --- ____________ -------- __ -------------- 59 

sp __ ------------------ __ ----- ______ --------------- _ _ _ _ _ _ __ _ __ _ __ _ __ __ _ _ _ _ 59 

Modiolus Lamarck ___________________ -- _____________________________________ 57-58 

Modiolus s. s __ ------------------------------ ______ ----- _________ ------------ 58 

fuscus Gmelin ____________________ -_ -- ____________________________ ------- 59 

(Brachidontes) curtulus Dan _______________________________________ 58, Pl. XV 

(Brachidontes) grammatus Dall ___________________________________ 58, Pl. XV 

? Modiolus (Botula) cinnamomeus Lamarck _________________________________ 58-59 

MoniB---------------------------------. ________ ---- ____ -------- ____ -------- 56 

Myoconcha (see Mytiloconcha)__ ________ __ _ _ _ __ ___ _ _ _ _ _ _ ___ _ _ __ _ _ _ __ _ _ ___ ___ 5': 

Mytilidae _ -- ____ ----- __________ -------- _____________________________________ 57-60 

·Mytiloconcha Conrad (see Mytilus)_________________________________________ 57 

incurva Conrad _ _ __ _ __ _ _ _ _ _ ___ _ __ _ __ _ __ _ _ __ _ _ _ __ _ _ _ _ __ _ ___ __ _ __ _ __ _ _ _ _ _ _ 57 

My til us Linnaeus --- _ _ _ __ _ __ _ _ _ _ _ _ __ _ __ _ __ _ __ _ __ _ _ _ _ _ _ __ ___ _ __ ___ _ _ _ _ _ ___ _ __ 57 

Mytilus s. s __ ------- ______ -------------------- ____ ---- _____ --------------- __ 57 

decussatus Montagu. _____________________ --------- ________ ------------- 59 

discors Linnaeus ________ -------- ______ ------------ _____ ------------ _____ 59 

edulis Linnacus __________________ ------------- _____ --------------------- 57 

bcsperianus Lamarck___________________________________________________ 57 

hirundo Linnaeus ________________ ------- ___ -------- _ _ _ _ _ __ __ ___ ___ _____ _ 39 

incrassata Conrad_______________________________________________________ 57 

Page 

Mytilus lithophagus Linnaeus ___________ ----------------------------------- 60 

modiolus Linnacus __________________________ --------- _____ -------------- 57, 58 

pandionis DalL ______ --------------------------------------------- 57, Pl. XIV 

(:\Iytiloconcha) incurvus Conrad __ -------------------------------------- 57 

N 

Neaera glacialis Sars ___________________ -------------------------------------- 64 

Nodi pecten DalL ____ -----------------------------------------------··------- 48 

Nucula ______________________________________________ --- _ ----- ___ ------------ 8 

arctica Gray ______________________ --------------------------------------- 20 

chipolana Dall __________________________________________________ 8, 9, 10, Pl. II 

waltonia Garuner, n. subsp ___________________________________ 8-9, Pl. II 

dasa Gardner, n. SP---------------------------------------------- 8, 9-10, Pl. II 

defuniak Gardner, n. SP------------------------------------------- 8, 10, Pl. II sinaria DalL ___________________________________________________ 8, 9, 10, Pl. II 

tenuisculpta Gabb __________ ------ ____ ------ _- -------------------------- 8 

Nuculidae ________________________ ----------- _ -- _____ ------------------------ 8-10 

0 

Oak Grove sand, age and rank oL-------------------------------------------

Ostrea (Linnaeus) Lamarck ________________________ ---_---_- __ -------------- 40-43 

compressirostra Say ____________________ -- ______ ------------------------- 43 

edulis Linnaeus ___________________ --------- ____ ------------------------- 40 

georgiana DulL _____________ -------- ___________ ------------------------- 43 

baitensis Sower by __________ ----------- ____________________ -------- 40, 41, 42,43 

imbricata Lamarck ______________________________ - _________ -------------- 42 

inflata Gmelin ______ --------- _____ ------ _______ ------------------------- 53 

isognomum Linnaeus ___________________ -------------------------------- 39 

lima Linnaeus __________________________________ --- ________ --- _ ---------- 52 

mauricensis Gabb ______________________________ --- _ --- _- __ -------------- 41, 43 

maxima Linnaeus ___________________ ------------------------------------ 43,44 

nodosa Linnaeus __________ ---------------------------------------------- 46 

normalis DalL _______________________ --------- ___ ---------------- 41, 43, Pl. XI 

pauciplicata Dan ________ -------------------------------------- 40,41,42, Pl. X 

percrassa Conrad _______________________________ -_----- ___ --- __ ---------- 43 

pleuronectcs Linnacus ________________ - _- ___ -___ ------- _ ----------------- 50 

podagrina Dall. ___________________________________________ -- _ -- 41, 42-43, Pl. X 

rugifera DulL _____________________________________________ -- ___ 40, 41, 42, Pl. X 

sellaeformis Conrad _ ------- ___________ ---- _____ --------- _-- ------------- 41 

trigonalis Conrad ________________________________ --- ________ ------------- 41-42 

virginiana Conrad-- ____________________________ -_________ --------------- 52 

virginica Guppy ___________________________________________ -------------- 112,43 

Ostreidae ________________________ ----- _ ---- _- _- --- ___ ----- _ ------------------ 4o-43 

p 

Pandora (Bruguiere) Lamarck ______________________ --_--_-- __ --------------- 82-63 

carolinensis Bush _____________________ ----------------------------------- 63 

(Kennerleyia) dodona Dan _________________________________________ 63, Pl. XV 

Pandoridae Gray--------------_--------------------------------------------- 62-63 

Pecten M tiller------ __ ---_-_------------------------------------------------- 43 

Pectens. s ______________ ----------------------------------------------------- 44 

acanikos Gardner, n. SP-------------------------------------- 44, 46, 47, Pl. XI 

alumensis Gardner, n. SP------·---------------------------- 44,47-48, Pl. XII 

burnsii Dan _________________________________________________ 44-45, 47, Pl. XII 

chipolanus _____________________________ ---- ______ -- _ ----- 44, 46, 47, 48, Pl. XII 

choctavensis Aldrich _____________________________ -- _______ --_--__________ 47 

circularis Sower by ___________ ------ ___ --- __________ - __ ------------------- 48 

comparilis Tuomey and Holmes_________________________________________ 48 

condylomatus Dall __________________________________________ 44,48-47, Pl. XII 

dislocatus Say------ ______ ----- ________ ---------------------------------- 48 

eboreus Conrad ________ -------------------------------------------------- 48 

exoticus Chemnitz ____ -- _ --. --------------------------------------------- iS 

gibbus Linnaeus ----------- __ --- ___ -------------------------------------- 44, 48 

hemicyclicus RaveneL ______ -_- ___ -------- __ ---------------------------- 44 

irradians Lamarck _____ ------------·------------------------------------- 48 

islandicus Milller -------------------------------------------------------- 45, 47 

jeffersonius edgecombensis Conrad_------------------------------------- 45 

kneiskerni Conrad _____ -------------------------------------------------- 47 

madisonius Say ______________________ ------------------------------------ 45,46 

maximus _________ ------------------------------------------------------- 44 

mortonL _ --------------------------------------------------------------- 44, 50 

nicholsi Gardner, n. SP------------------------ ----------------- 44,48, Pl. XII 

nucleus Linnaeus ___ ----------------------------------------------------- 48 

pleuronominis 'Yoodring ______________ ----------------------------------- 46 

poulsoni Morton ___ ----------------------------------------------------- 44 

pseudamussium Sower by------------------------------------------------ 48 

purpuratus Lamarck_--_------------------------------------------------ 48 

sayan us DulL _______ --------------------- _____ -------- 4.3, 44,45-46,48, Pl. XII 

thetidis Dall _________ --------------- _-- ---------------------------------- 46 

ventricosus Sower by __ -------------------------------------------------- 48 

(Amusium) precursor Dan _____________________________ ----------------- 50 

(Chlamys) madisonius Conrad_----·------------------------------------ 2 

(Pecten) burnsii DulL _______________________________________ 44-45,47, Pl. XII 

sp. indet _____________________________ -------------------------------- 45 
INDEX III 

Page 

Pecten (Pseudamussium) defuniak Gardner, n. SP------------------ 44,49, Pl. Xll 

diktuotum Gardner, n. sp -----------------------------------.44,49-50, Pl. XII 

guppyi Dall •.. --------------------------- ___ ------------------------- ___ 49, 50 

sp _. _____ -------- __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ __ __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ 50 

Pectinidae ____ ------------- __________________________________________________ 43-50 

Pectunculus aratus Conrad ... ___________ __ _ __ _ _ _ _ _ _ _ __ _ __ _ __ _ _ _ __ _ _ _ _ ___ _ __ _ 38 

charlestonensis Holmes .. ________________________________________________ 38 

pectiniformis Lamarck._------ ________________ --------__________________ 38 

Pedalion (Solander MSS.) Huddesford. _ _ _ __ __ _ _ _ __ _ _ _ _ _ _ _ _ _ __ _ __ __ _ __ _ _____ S9 

solereperta (Maury)----------___________________________________________ S9 

Pedalionidae _ _ _ _____ _ _____ __ _ __ __ _ _ __ __ _ __ __ _ __ _ __ ___ _ __ __ _ __ ___ _ _ _ __ _ ___ _ __ 39 

Periploma Schumacher------- _______________________________________________ 61-62 

discus Gardner, n. SP-------------------------------------------- 81-82, Pl. XV 

inaequivalvis Schumacher _______________________________________ -------- 61 

peralta Conrad ______ ----- __________ ------------------- __ ------ __ -------- 62 

Periplomatidae ___ ------- ___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ __ _ _ _ __ ___ 61 

Perna (see Pedalion) _______________________________ ----------------- _________ 39 

ephippium Linnaeus. _____________________________ ------- _ _ _ _ _ _ __ _ _ ____ _ 39 

Philippi, R. A., cited ______________________________ ------------- _____ -------- 24 

Pinna nigra Chemnitz ____________________ ----- _ -------- _____ ----- ___ -------- 39 

Pinnidae _______ ------------- ______________________________ ----- _________ ---- 39 

Plagiarca Conrad ______________________ ----- _____ ------ _____________ --------- 26 

Plagioctenium Dan ______________________________ . ___________________ .------- 48 

Plectodon Carpenter._. ____ --------... __________ . _________ .----------------- 64 

scaber Carpenter-_-------- ___ . __ . ______ . _____ ------ ________________ ----- 64 

Plicatula Lamarck._. __ ------ ___ -------- ________ . _________ .. __ .------------- 51 

densata Conrad------------------------------------------------ 51-52, Pl. XIII 

gibbosa Lamarck ___ ------ ________ ----------- __ . __________ . ___ ----------- 51 

lepidota Gardner, n. SP----------------------------------------- 51, 52, Pl. XIII 

marginata Say----------.-----. __ -----... __ . ___________ . _______ ._________ 52 

ramosa Lamarck .. -------- ____________________ ------------______________ 51 

Pododesmus Philippi__ _______ ------- __ -------------------------------------- 55 

abnormalis Gray.-------------------------------- ______ .________________ 5.'\ 

decipiens Philippi_ ______________________ -------------------------------- 55 

echinata Broderip_____ _ _ _ __ _ ____ __ _ __ ___ __ _ __ _ __ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _____ ___ 55 

harfordi Reeve._-------------------- _________ -----------_.-------------- 55 

rudis (Broderip) GraY--------------------------------------------- 55, Pl. XIII 

scopelus Dall.----------------------------------------------------- 55, Pl. XIII 

Poromyacea DalL. ------ ___ ----------------------------------------------- __ 8S 

Prasina borbonica Deshayes--------------------------------------- _ ___ ____ __ 61 

Prionodesmacea and Anomalodesmacea, distributio..J. of species oL __ __ __ __ __ 5-7 

Pseudamussium, H. and A. Adams__________________________________________ 48 

defurltak Gardner, n. SP----------------------------------------- 44, 49, Pl. XII 

diktuotum Gardner, n. SP------------------------------------ 44,49-50, Pl. XII 

Pteria ScopolL _________ ----- __ --- _ ------. _____ . __ -- _ --- __ -------- ____ __ _ __ __ 39 

argentea _________ ----------------- ____________ .. ____ ------------------ __ 40 

chipolana Dall. ____ ------------- __ -------- _______________ --------------- 40 

multangula H. C. Lea--------------------------------------------------- 40 

radiata Leach-------------------------- ______ .-- ____ --- __________ ------- 40 

Pteriidae ---------------------------------•. --.-----.. ----.--.-------- _______ 39-40 

s 

Say, Thomas, cited·--------------------------------------------------------_ 35 

0 

Page 

Scapharca Gray (see Area and Diluvarca>----------------------------------- 28 

clisea. ______ ------ _______________________________ -- _--------------- _- _ _ _ _ 32 

Scapharca dodona DalL ____________ ----------------------------------------- 30 

(Anadara) aresta Dan ____________________________ ---- __ ---_.--------. __ • 29, 33 

(Cunearca) initiator Dall ____ --------------------------------- 23, 34, 35, Pl. V 

(Scapharca) acompsa Dan ________________________________________ 23, SO, Pl. V 

dodona Dall __________________________________________________ 23, SO, Pl. V 

hypomela Dall ____________________ ---------------------- 23,29-30,30, Pl. V 

latidentata Dan ____________________________________________ 23,28-29, Pl. V 

santarosana Dall ____ -------------------------------------- 23, 31, 33, Pl. VI 

staminata DalL. ____________________________ --.--- __ 23, 3G-31, 32, 33, Pl. V 

strebla Gardner, n. sp. ______ --------------------------- 23,33-34, Pl. VIII 

Seguenza ___________ --------------------------------------------------- ---- 16 Shoal River marl member, fauna of.. _______________________________________ _ 

Simpson, G. B., and Dall, W. H., cited_------------------------------------ 59 

Sower by, G. B., cited.------------------------------------------------------ 42 Spondylidae __________________________________________ -. __ . ___ --------.-----. 5G-52 

Spondylus Linnaeus _________ ----- _ -- _ ----- _ --- _. ---------------------------- 50 

bostrychites Guppy_---------------------------------------------------- 2, 51 

chipolanus DalL -------------------------------------------------------- 51 

gaederopus Linnaeus. --------------------------------------------------- 50 

inornatus Whitfield. ___ ---------------------- ___ ---------.. --_---------- 51 

sp. cr. S. bostrychites Guppy------------------------------------------- 51 

T 

Tellina cuspidata OlivL. --------------------------------------------------- 64 

inaequivalvis Linnaeus _____ ---------------.----------------------------- 62 

Thracia (Leach MS.) De Blainville ••. --------------------------------------- 82 

corbuloidea De Blain ville._. ____ ---- _____________ --------------------.-- 62 

sp. indet. __ --------------------------- _ --------------------------------- 82 

transversa Lea.-----------.... ----- _______ -----------------.-.. ---------- 62 

Thraciidae _______ --------- _ ---------- _ -------------------------------------- 62 

Trigonocoelia crassa Deshayes ______________________ ------------------------- 21 

Trigonulina D'Orbigny __ --------------------------------------------------- 83-84 

ornata D'Orbigny ------------------------------------------------------- 63 

Trinacria C. Mayer_.------------------------------------------------------- 21 

meekii Dall _____________ -------------------- ___ . ---------------- 21, 22, Pl. IV 

parameekii Gardner, n. subsp -------------------------------- 21, 22, Pl. IV 

v Verticordia (Searles Wood MS.) SowerbY----------------------------------- 83 

cardiiformis Sower by---------------------------------------------------- 63 

cossmanni Dan _______________________ --------------.-------.. ----------- 64 

(Trigonulina) dalli Gardner, n. SP---------------------------------- 64, Pl. XV 

Verticordiidae _______________ ------------------------------------------------ 63-64 

w 

Wakullina Dall __________________ .------------------------------------------- 58 

y 

Yoldia Miiller --- ·----------------------------------------------------------- 20 

frater Dall-------------------------------------------------------- 20-21, Pl. IV 

laevis Say_-------------------------------------------------------------- 20 

limatula Say ___ --------------------------------------------------------- 20 

soror Gardner, n. SP---------------------------------------------- 20, 21, Pl. IV