Owl Creek 

(Upper Cretaceous) 

Fossils from Crowleys Ridge 

Southeastern Missouri

GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-E
Owl Creek 

(Upper Cretaceous) 

Fossils from Crowleys Ridge 

Southeastern Missouri

By LLOYD WILLIAM STEPHENSON

A SHORTER CONTRIBUTION TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-E

Supplemented with descriptions and illustrations 

of better preserved shells from the type section of 

the Owl Creek formation 2.$ miles northeast of 

Ripley^ Tippah County^ Miss.

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price $1 (paper cover)
CONTENTS

Abstract.----_-________--_--_____-_.._______ ________

Introduction..--___________________________________

Physiographic setting.______________________________

Stratigraphy and lithologic character of the formations __ 

Structure-_________________________________________

Fossil localities.____________________________________

Correlation. _______________________________________

Systematic descriptions._____________________________

Porifera.______________________________________

Spongiae________________________________

Annelida. ____________________________________

Chaetopoda.__ _____________________________

Mollusca. _____________________________________

Page Page

97 Systematic descriptions—Continued

98 Mollusca—Continued

99 Pelecypoda__-_-_---__________ ——— _____ 106

100 Prionodesmacea___-_---_---_---_------_ 106

102 Anomalodesmacea_ _____________________ .115

102 Teleodesmacea__---_-_----_-_---_-----_ 117

105 Gastropoda____________________ 124

106 Ctenobranchiata--___------_-----------_ 124

106 Opisthobranchia_-_--_--------_-_------_ 132

106 Cephalopoda.._________________________ 134

106 Ammonoidea_-____------__-_-_-_-----__ 134

106 Literature cited._______________________________ 136

106 Index- 139

ILLUSTRATIONS

[Plates follow page 140]

Page

PLATE 14. Views of Clayton (Paleocene), Owl Creek and McNairy (Upper Cretaceous) formations, in Stoddard and Scott 

Counties, Mo.

15. Cliona, Hamulus, Nucula, Nemodon, Glycymeris, Nuculana, and Idonearca.

16. Trigonia, Tenuipteria, Pinna, Ostrea, and Exogyra.

17. Pecten, Crenella, Cuneolus, Anatimya, and Lima.

18. Veniella, Scambula, Brevicardium, and Pholadomya.

19. Cardium, Crassatella, and Liopistha.

20. Cardium, Aphrodina, Legumen, Tenea, Tellina, Leptosolen, Linearia, and Cyprimeria.

21. Goniochasma, Napulus, Helicaulax, Polinices, Gyrodes, Pseudomalaxis, Gastrochaena, and Panope.

22. Liopeplum, Morea, Anchura, Fusinus, Drilluta, Turritella, and Trobus.

23. Volutomorpha, Eoharpa, Caveola, Eoacteon, Bullopsis, and Discoscaphites.

24. Sphenodiscus and Baculites.

FIGURE 21. Sketch map showing Owl Creek fossil localities in Crowleys Ridge____--_-__-_______-_-___-__-_-__________- 103

in

A SHORTER CONTRIBUTION TO GENERAL GEOLOGY

OWL CREEK (UPPER CRETACEOUS) FOSSILS FROM CROWLEYS RIDGE,

SOUTHEASTERN MISSOURI

By LLOYD WILLIAM STEPHENSON

ABSTRACT

The Owl Creek formation, which is typically developed in 

Tippah County, Miss., is now known to extend northward to 

the head of the Mississippi Embayment in southeastern Missouri. The formation is represented in Crowleys Ridge in 

Stoddard and Scott Counties, Mo., by 11 feet or less of weathered, 

mottled, yellowish-brown and greenish-gray, glauconitic, finely 

micaceous sand or sandy clay, indurated in part to ferruginous, 

argillaceous sandstone. In Missouri the formation is unconformably underlain by the McNairy sand (Upper Cretaceous), 

and is unconformably overlain by the Clayton formation 

(Paleocene). Fossils, mainly mollusks, are contained in the 

Owl Creek formation of Missouri in greater or less abundance; 

they are in the form of internal and external molds only; no 

shell material has escaped solution and removal by circulating 

ground waters, but many of the molds are identifiable.

Fifty-six species are identified and described in this paper. 

All of them occur also in the typical Owl Creek formation of 

Mississippi, where their shells have been more or less completely preserved, some in almost as perfect condition as the 

shells on a modern ocean beach. In describing the Missouri 

specimens it has seemed desirable in order to present their 

characteristic features more clearly, to include supplementary 

illustrations of the more perfect shells of the same species from 

Mississippi. Four new genera and nine new species are described. Although these new forms are present as molds in 

Missouri the holotypes and some of the paratypes are selected 

from among the more perfect Mississippi shells.

For the 4 new genera, including 1 pelecypod and 3 gastropods, 

the names Tenuipteria, Trobus, Eoharpa and Eoacteon are proposed ; the new species are the pelecypods Crenella microstriata, 

Cardium (Oranooardium) lowei and Tellina buboana, and the 

gastropods Pseudomalaxis pateriformis, Trobus buboanus, Helicaulax formosa, Morea transenna, Liopeplum rugosum, and 

Eoharpa sinuosa.

The Owl Creek formation is the youngest and stratigraphically the highest Upper Cretaceous formation present in outcrop in the eastern Gulf region. In terms of the European classification the formation falls within the Maestrichtian stage 

(upper part of Upper Cretaceous).

INTRODUCTION

The Owl Creek formation, the uppermost Cretaceous 

formation at the surface in northern Mississippi, which

is typically developed in Union and Tippah Counties, 

crops out in a narrow, irregular strip extending from 

the vicinity of New Albany, Union County, northward 

through Tippah County to and beyond the Tennessee 

State line (Stephenson and Monroe, 1940, p. 226-248, 

pi. 1A; Conant and McCutcheon, 1941, p. 25-27, pi. 1). 

North of the State line the belt of outcrop has been 

mapped about half way across Hardeman County, beyond which in Tennessee and Kentucky the formation 

is concealed by overlapping Paleocene and Eocene strata 

(Wade, 1926, p. 7,8, fig. 1).

In Mississippi the formation typically consists of 20 

to 40 feet of dark compact, fine-grained, micaceous, glauconitic sand and sandy clay, in part calcareous; it contains an abundance of marine fossil organisms, chiefly 

mollusks, many of which are in an unusually fine and 

complete state of preservation. About the middle of 

the 19th century Dr. W. Spillman of Columbus, Miss., 

collected fossils at the locality that was later designated 

the type locality of the formation; it is on Owl Creek 

3 miles [21/2 miles] northeast of Eipley, Tippah County (Ei/2 sec. 7, T. 4 S., E. 4 E.). The section exposed 

on Owl Creek was described by Hilgard (1860, p. 88). 

The fossils were submitted to the pioneer American 

paleontologist, T. A. Conrad (1858), who described 56 

new species of mollusks. A few additional species 

have been described by Conrad (1860), and by other 

authors in more recent years, but the Owl Creek fauna 

has never been as thoroughly studied as its importance 

justifies. The formation is separated from the underlying Eipley formation and from the overlying Clayton formation by erosional unconformities.

Authors who have contributed substantially to our 

knowledge of the unit now called Owl Creek formation 

in Mississippi and Tennessee include in chronologic 

order: Conrad (1858, 1860); Hilgard (1860); Crider 

(1906); Wade (1926); Stephenson and Monroe (1937, 

1938, 1940); and Conant and McCutcheon (1941).

(97)
98 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Strata presumed to be of Ripley (Late Cretaceous) 

age were known and mapped to the extreme head of the 

Gulf Embayment in southern Illinois as early as 1906, 

but no fossils were discovered in them and they were 

considered to be of nonmarine origin (Glenn, 1906, 

p. 27-29, pi. 1). More recent investigations have failed 

to disclose fossils in these beds in Illinois on which to 

base a correlation, but the geographic and stratigraphic 

relationship of the beds with reference to other known 

formations indicate that they are the northern extension 

of the McNairy sand member of the Eipley formation of 

Tennessee and Kentucky.

Lamar and Sutton (1930, p. 853-854, fig. 1) state 

that the Ripley of southern Illinois is unconformably 

overlain by the Porters Creek clay. He did not 

recognize the Clay ton formation (Paleocene) between 

the Ripley and the Porters Creek. At the old Olmstead ferry landing the Porters Creek clay is 60 or TO 

feet thick; the upper 30 feet is mined as fuller's earth. 

Lamar reports indistinct imprints of marine fossils that 

are too poorly preserved for identification in the fuller's 

earth in Illinois. I visited the Olmstead locality in 

1936 and found paleontologic evidence in a small, poor 

exposure along an old abandoned road about 100 yards 

upstream from the old Olmstead ferry landing that the 

Clayton formation is present beneath the Porters Creek 

clay. The section here is as follows:

Section along an old abandoned road 100 yards 

from the old Olmstead ferry landing, PulasJci 

County, III.

Paleocene series:

Clayton formation: Feet 

Sand, greenish-gray argillaceous, richly glataconitic__________________________ 2 

Sand, weathered brown, ferruginous, argillaceous,, glauconitic, with many chert pebbles 

in lower 18 inches; contains poorly preserved 

prints of fossils in lower 2 feet; recognized 

Venericardia sp. (of the V. planicosta group), 

Idonearca saffordi (Gabb), Turritella sp___ 4l/2 

Unconformity. 

Upper Cretaceous series: 

McNairy sand:

Sand, fine white micaceous____________ 2 

Concealed to water level___________________40±

The position of the preceding section is stratigraphically below the Porters Creek clay, and the recognized 

fauna in the glauconitic sand is sufficient to identify the 

Clayton formation. In a later visit to the Olmstead 

locality when the Ohio River was at flood stage several 

poor exposures of the richly glauconitic sand of the 

Clayton formation were seen in the immediate vicinity 

of the old ferry landing, but no additional fossils were 

found.

Prior to 1932 neither the Clayton formation nor the 

Porters Creek clay were known west of southern Illinois in southeastern Missouri; however, prophetic of 

their discovery Lamar and Sutton (1930, p. 853) said:

West from Pulaski County, Illinois, the formation dips below 

younger sediments and is not known to occur elsewhere at the 

surface, unless the gray clay reported at Idalia and Bloomfield, 

Missouri, is Porters Creek—a conclusion which a study of well 

records of the region seems to justify.

Lamar and Sutton also stated (p. 855-856) :

Clays ascribed to the Lagrange, probably either the lower 

part or the dark gray upper phase described later, are also 

exposed near Idalia and Bloomfield, Missouri, in Crowleys 

Ridge. These clays have been called the Idalia shale by Marbut [1902, p. 21-23], who describes the clays as "uniformly 

dark in color and, where freshly exposed, it is black, very 

much resembling the dark shales of the Coal Measures". About 

60 feet of this clay is exposed near IdWia, * * *. As previously stated, it is thought that the gray clay exposed at Idalia 

and Bloomfield may be the upper part of the Porters Creek 

formation instead of one of the Lagrange clays.

The clays at Idalia and Bloomfield were later mapped 

by Farrar (1935, pi. 6) as Midway group (Clayton 

formation and Porters Creek clay).

Before 1932 the Owl Creek formation, as such, was 

not known in outcrop in the Gulf Embayment area 

north of Hardiman County, Tenn. In 1932 the late 

F. E. Matthes, who was then engaged in physiographic 

studies in southeastern Missouri, discovered fossil imprints in a thin layer of greenish-gray oolitic, glauconitic, somewhat sandy clay, which crops out in a road 

bank in the southeast-facing slope of Crowleys Ridge, 

0.35 mile northwest of Ardeola station, Stoddard County, Mo. (pi. 14, A, B). He collected a chunk of this 

material and submitted it to me for the determination 

of the fossils. I recognized several well-known Upper 

Cretaceous species. (Matthes, 1933, p. 1007-1009.}

A collection made from the oolitic clay in January 1933 by Willard Farrar of the Missouri Geological 

Survey and Water Resources showed that, in addition 

to the. Cretaceous fossils, the clay contained several 

characteristic Clayton (Paleocene) fossils. Field investigations in 1933 by the Missouri Survey and by the 

present author proved that the bed of oolitic clay is 

in fact the basal bed of the Clayton formation which, 

together with an overlying section of Porters Creek 

clay, represents the Paleocene series (Midway group) 

in the Gulf Embayment area. It was found that the 

Cretaceous fossils in the oolitic clay were derived by 

mechanical reworking from a bed of ferruginous, 

micaceous, fossiliferous clayey sand and sandy clay 

(Cretaceous) in place immediately beneath the oolitic 

clay. This reworking must have taken place before 

the calcareous material composing the shells of the organisms was leached away, for the clay contains only
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 99

the imprints of the fossils. The fossils in the Cretaceous bed are also present as imprints only, but they 

represent an abundant fauna that includes many characteristic species of the Owl Creek formation of Mississippi. The sand is lithologically like that of the 

typical Owl Creek except that the calcareous content 

has been removed in solution by circulating ground 

waters, and the iron in the glauconite has been oxidized 

to reddish, brownish, and yellowish hematitic and 

limonitic compounds.

Before the discovery of Cretaceous fossils in Crowleys Ridge the beds now known to be of that age were 

believed to be of Tertiary age and were so classified 

and mapped by Marbut (1902). One of the reasons 

for this erroneous correlation was the mistaken assumption that masses of quartzitic sandstone in the McNairy sand at Bell City in northeastern Stoddard 

County, and elsewhere in adjacent parts of Crowleys 

Ridge, were of the same age as similar quartizitic masses 

in the Wilcox formation farther south in Crowleys 

Ridge in Clay, Greene, and Craighead Counties, Ark. 

The discovery of the Cretaceous and Paleocene fossils throws new light on the geologic history of the 

Gulf Embayment, for it shows that the seas in which 

the Owl Creek and Clayton formations were deposited extended northward to the extreme head of 

the embayment area.

Following the discovery of Cretaceous and Paleocene strata in Crowleys Ridge in southeastern Missouri, representatives of the Missouri Geological Survey and Water Resources were assigned to study the 

general geology, stratigraphy, and economic resources 

of the area, and reports, including areal geologic maps, 

were issued on these subjects. The report of most interest in connection with the present paper was prepared under the authorship of Willard Farrar (1935) 

and is entitled "The Cretaceous and Tertiary geology." 

The Cretaceous fossils listed in this report were identified by me, and the Paleocene fossils by Julia Gardner. This report was followed by one entitled "The 

geology of Stoddard County, Missouri," under the authorship of Farrar and McManamy (1937). In March 

1933, it was my privilege to spend a short field season in the area with Farrar and with H. S. McQueen, 

of the Missouri Survey. Again in April 1938,1 spent 

2 days in the area with H. S. McQueen, D. R. Stewart 

and Lyle McManamy of the Missouri Survey, and 

with W. H. Monroe of the United States Geological 

Survey.

PHYSIOGRAPHIC SETTING

Crowleys Ridge is an attenuated remnant of a hilly 

part of the Coastal Plain that has withstood the erosional attack of two large rivers, the Ohio and the 

Mississippi. The ridge is about 200 miles long, extending from Mississippi River below Cape Girardeau, Mo., 

to Helena, Ark.; the ridge is extremely irregular in outline and height, ranging in width from less than 1 mile 

to 18 miles, and rising to a maximum of about 580 feet 

above sea level and 260 feet above the surrounding lowlands. The continuity of the ridge is broken by four 

erosional gaps now traversed by streams. Little River 

traverses a gap about 9 miles wide in Scott and Stoddard Counties, and Castor River flows through a narrow 

gap in Stoddard County; St. Francis River passes 

through a narrow gap on the Missouri State line; and 

L'Anguille River traverses a gap 8 miles wide in Lee 

County, Ark. The part of the ridge between the Little 

and Mississippi Rivers, Missouri, is locally known as 

the Benton Hills and the part in Stoddard and Dunklin 

Counties as Bloomfield Ridge.

In his treatise on the geology of Crowleys Ridge, Call 

(1891, p. 128,129) recognized that the lowland between 

the ridge and the Ozark province on the west was cut 

and partly refilled with sediments by the Mississippi 

River at a time when the course of the river was west of 

the ridge as far south as Helena, Ark., where it joined 

the Ohio River. Call says:

The Mississippi entered the great embayment just below Cape 

Girardeau and spreading into several considerable streams 

rapidly engaged in the work of denudation and removal. Two 

main channels were formed, one east, and the other west of 

Crowley's Ridge. That is to say, such was their relation to 

what is now that ridge. The great valley through which flows 

the White, lower Black, Cache, and other smaller streams was 

then dug out. On the west the great trough of the Mississippi 

was then deeper and wider than that of the Ohio to the east. 

At length the waters of the Mississippi cut through and passed 

to the east of the ridge and its work west of the ridge ended.

Although Call recognized some of the major facts in 

the geographic relationship of the Mississippi to the 

Ohio River his description of that relationship is somewhat confused and he did not offer a detailed explanation of how the Mississippi was diverted from its eourse 

west of Crowleys Ridge to join the Ohio in the vicinity 

of Cairo.

The physiography of Crowleys Ridge, as interpreted 

by Marbut (1902), and later with certain modifications 

by Matthes (1933), tells the astonishing story of the 

capture twice of one great river by another—the Ohio 

the "captor" and the Mississippi the "captured." The 

story is briefly summarized in the following paragraphs.

In early Quaternary time the Ohio River flowed to 

the southeast of a coastal-plain upland of which Crowleys Ridge is now an attenuated erosional remnant. At 

the same time the Mississippi River turned to the west 

and southwest at Cape Girardeau, Mo., and flowed to
100 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

taceous, Paleocene, Eocene, Pliocene(?), Pleistocene, 

and Recent ages. The following generalized section 

based, with modifications, on the published results of 

the researches of Willard Farrar and his associates on 

the staff of the Missouri Geological Survey and Water 

Resources, pertains to Scott and Stoddard Counties 

(Farrar, 1935, p. 10-28; Farrar and McManamy, 1937, 

p. 14-44).

Generalised section of rocks in Crowleys Ridge, 

Missouri

[Maximum known thicknesses are given] 

system:

the south on the west side of the upland. The two rivers 

came together in the vicinity of Helena, Ark., and continued as a single stream to the Gulf of Mexico. In the 

Cairo region near the head of the Gulf Embayment the 

gradient of the Ohio Kiver was supposedly about 20 

feet lower than that of the Mississippi.

The drainage on the upland in the region of Scott and 

Stoddard Counties was to the northwest to the Mississippi, the small tributary valleys of course becoming 

deeper in that direction. The Ohio meandering in its 

flood plain east of the upland scoured away the southeast side of the upland, which became continuously narrower. The valleys of the northwestward-flowing tributaries thus were beheaded forming notches in the profile 

of the upland along its south edge and, as cutting con- tds, and gravels of flood piains_________ 20

tinued, the notches grew progressively deeper. Eventu- Pleistocene series:

ally one of the notches corresponding to the geographic Terrace deposits________________ 80

position of the present Little River became so low that Loess______________________ 70

the flood waters of the Mississippi spilled through it Unconformity.

and flowed southward to the lower flood plain of the Tertiary system:

Ohio. Repeated floods continued to cut the notch deeper Pliocene series:

and wider until eventually the great Mississippi aban- vncon^mXTM*' "* ***' unnamed"—"——— *

doned its channel in the Advance Lowland and, follow- ,, c°n °r *

. . ' Eocene series:

mg the course 01 the present Little River, joined the wilcox formation__ __ __ _ __ __ 250

Ohio in that part of its flood plain which Marbut called Unconformity.

the Morehouse Lowland. The Mississippi River must Paleocene series:

have followed this course for a relatively long time for Porters Creek clay——————————————— 100

the gap that it produced in Crowleys Ridge is nearly 9 Clayton formation——————————————— 10

miles wide. Unconformity.

While this great shift in the course of the Mississippi C****0118 gystem:

, , . , ,1 , , . ,, , , ,, ,, Upper Cretaceous series:

was taking place another notch in the upland, south of „ , ~ , . ^

_, _.. fe *r , . i , Owl Creek formation————————————————— 11 Cape Girardeau, was being lowered in the same manner Unconformity.

as that in the Little River area. Eventually a second NcNairy sand_________________ 181

capture of the river was accomplished through this Unconformity,

notch, which diverted its course to the channel it now Devonian system )

occupies from Cape Girardeau via Commerce to Cairo. Silurian system ^differentiated sandstones, "*+

_,, , , .,, T .,^. x-x,..,.! stones, dolomites_————————— 120+ The channel now occupied by Little River was, in its Ordovician system I ___

turn, abandoned by the Mississippi River. 902+

Marbut (1902, p. 3-7) named the great lowland west The Owl Creek formation as it is exposed in the

of Crowleys Ridge the Advance Lowland, from the vil- section at the discovery locality near Ardeola is typical

lage of Advance 24 miles southwest of Cape Girardeau. and its stratigraphic relationship to underlying and

He applied the name to the lowland to and "beyond" the overlying formations is shown most completely and

Arkansas State line. Stephenson and Crider (1916, most clearly there. The description of the Ardeola

p. 25) expanded the application of the name Advance section given by Farrar (1935, p. 16) is, with certain

to include the whole of the lowland in Arkansas be- modifications, repeated here. One important modificatween Crowleys Ridge on the east and the Ozark tion is the transfer of the lower 11 feet of his Owl Creek

province on the west. unit to the McNairy sand, and the recognition of an

unconf ormable relationship between the McNairy sand 

STRATIGRAPHY AND LITHOLOGIC CHARACTER OF ^ ^ Qwl Creek as here int ted. Qther ^^

THE FORMATIONS . ' f . n ~

in fetoddard and bcott Counties, in which the Owl Creek

The sedimentary rocks composing the northern part formation is present, are less completely exposed that 

of Crowleys Ridge include beds of Paleozoic, Late Cre- the one near Ardeola. (See pi. 14, following p. 140.)
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 101

Section along road in southeast-facing slope of Croivleys Ridge, 

0.85 miles northwest of Ardeola in NWy^NW^ sec. 10, T. 27 N., 

R. 11 E., Stoddard County, Mo.

[Altitude at top of section 493 ± feet]

Quaternary system: Feet

Pleistocene series:

Loess, yellowish-brown_______________ 5 

Unconformity. 

Tertiary system: 

Pliocene series:

Gravel, brown, well-rounded pebbles, and some 

red sand—————————______________ 6

Unconformity. 

Paleocene series: 

Midway group:

Porters Creek clay:

Clay, dark-green on fresh surface, weathering to light gray, locally including 

interstratified beds of ferruginous 

clay ____________________ 47 

Clayton formation:

Clay, pale-green, sandy, very glauconitic, 

oolitic in lower part, containing white 

angular sand grains near base; abundantly fossiliferous, including indigenous species and reworked Owl Creek 

species__________________ 5 

Unconformity. 

Cretaceous system:

Upper Cretaceous series: 

Owl Creek formation:

Sand, yellowish-brown, argillaceous, glauconitic, finely micaceous; contains many 

prints of fossils________________ 5 

Clay, greenish-gray mottled with yellow and 

brown, sandy, sparingly glauconitic, finely 

and strongly micaceous; contains a few 

prints of fossils________________ 6 

Unconformity, contact sharp. 

McNairy sand:

Clay and sand, brown, laminated, crossbedded, with parting planes of muscovite 

mica; contains abundant comminuted 

plant remains; borings in upper 8 or 10 

inches are filled with sandy matrix from 

overlying Owl Creek formation______ 11 

Sand, grains angular, white to bright orange, 

crossbedded, lignitic, locally cemented with 

limonite__—_——________—____— 11 

Clay, brown, light- and dark-gray to black, 

with interbedded sand; limonite and muscovite mica along bedding planes_—_ 27 

Lignite, very sandy_______________ 1 

Sand, grains angular, white, with iron oxide

stains, somewhat lignitic__________ 11 

Concealed to lowland level__________ 38

173

A sample of the pale-green oolitic clay at the base of 

the Clayton formation was studied critically by E,. C. 

Erd (written communication), whose report is quoted 

as follows:

347625—55———2

The sample is composed of clay oolites or pellets, ranging in 

size from 0.1 to 0.5 mm, and other mineral grains in a matrix 

of olive-green montmorillonite clay. The pellets comprise about 

80% of the sample. In most instances detrital mineral grains 

or glauconite serve as nuclei for the oolites. The nuclei are 

surrounded by massive light-green montmorillonite (mean index of refraction=1.555), which in turn is encased by concentric shells of montmorillonite. The individual montmorillonite 

crystals apparently lie with their plates tangential to the 

sphere. This oriented aggregate shows maximum birefringence 

(a'=1.53, r'=1.56) and pleochroism (-3T=pale brown, YZ=dark 

reddish brown). In many cases the oolite is merely a hollow 

shell of the oriented montmorillonite about a detrital grain, 

possibly as the result of shrinkage of the montmorillonite. The 

oolite itself has in almost all instances shrunk (?) away from 

the surrounding clay matrix leaving a smooth and lustrous 

surface.

The clay matrix is a light to olive-green montmorillonite 

with a mean index of refraction of 1.555 and appears to be 

similar to the massive montmorillonite in the pellets.

A few detrital grains and glauconite occur directly in the 

matrix in addition to those found in the oolites. The light fraction consists of subangular water-clear quartz with a few inclusions of biotite (?), apatite, and epidote; subangular to subround translucent quartz; angular fresh orthoclase; and 

microcline, some of which is being replaced by montmorillonite 

along cleavage cracks. The heavy fraction constitutes only a 

little of the sample. The minerals in approximate order of 

abundance in the heavy fraction are:

Opaques (% to % of the heavy fraction, mostly iron 

minerals), kyanite, zircon, staurolite, garnet, epidote, rutile, 

tourmaline, hornblende, muscovite, biotite, and chlorite. Almost all of the detrital grains are coated with montmorillonite, glauconite, or limonite.

Little or no phosphatic material is present and the amount 

of carbonate is negligible. The latter evidently has been 

leached from the rock for molds of shells, with delicate features well-preserved, are common. The shells are filled with 

both matrix clay and oolites although finer structures are preserved by the montmorillonite matrix alone.

Typical, nodular, dark-green glauconite with aggregate 

polarization is commonly found in the sample both as nuclei 

of the pellets and in the matrix. The chief occurrence of 

glauconite, however, is as slightly curved and twisted tubes 

which are polygonal in cross-section and closely resemble the 

faecal pellets figured by Moore (1939, p. 520, fig. 1-a, c, m). 

In longitudinal section the glauconite is seen to have a micaceous structure and to have expanded perpendicular to the 

basal cleavage in a manner similar to vermiculite. Optically 

the glauconite is biaxial negative, a'=1.593, T'=1.610, mean index of refraction «=< 1.61, 2V is approximately 20°. These 

glauconitized faecal pellets are most commonly found as nuclei 

of the montmorillonite oolites.

A primary origin for the clay oolites, possibly coincident 

with the reworking of the underlying Cretaceous bed, seems 

likely. It is possible, however, that calcareous oolites have been 

partially or wholly replaced by clay and the remaining carbonate 

leached out.

In addition to the faecal pellets mentioned by Erd 

there are scattered through the oolitic clay a few clusters 

of larger pellets that resemble in form another kind of
102 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

faecal pellets illustrated by Moore (1939, p. 520, fig. If). 

In a subsequent study Erd reports on these as follows:

Large faecal pellets are abundantly present in these samples 

but were not found in the material submitted earlier. The 

pellets are grouped together usually with their long axes in 

sub-parallel arrangement. The pellets are normally round in 

cross-section but some have been squeezed together to produce 

a polygonal cross-section. Impressions of the oolites and 

detrital grains may be seen on the surface of the pellets, but 

they do not contain these objects. They are unique in this 

respect for even the matrix montmorillonite found in the molds 

of shells contains oolites and detrital grains. The large pellets 

do, however, contain about 10-20% of angular grains of quartz.

The pellets are composed of gray-green montmorillonite which 

is similar to that in the matrix and has the same mean index of 

refraction.

These pellets differ from the glauconitic (faecal?) pellets in 

composition, size (the small pellets are about 0.5 mm long by 

0.15 wide), abundance (the small pellets are much more common 

and may make up 20% of the sample), and in grouping (they are 

scattered throughout the sample).

It is interesting to note that the oolitic clay in the 

Ardeola section is at the same stratigraphic position as 

the fossil mollusks replaced by clay of the montmorillonite group in a railroad cut half a mile south by west 

of Pontotoc, Pontotoc County, Miss. The latter occurrence was recorded by Stephenson (1939, p. 96-99, pi. 

16) and later by Ross and Stephenson (1939, p. 393-397, 

fig. 1). At the Pontotoc locality the replaced fossil 

shells are in the basal bed of the Clayton formation of 

the Midway group (Paleocene), immediately and unconformably above glauconitic sand representing the 

southward extension of the Owl Creek formation. 

This identity of stratigraphic position is probably not 

accidental; it would seem to indicate a similarity in 

marine physical conditions in the Gulf Embayment area 

in early Midway time, extending from northern Mississippi to southeastern Missouri.

STRUCTURE

In structural attitude the Upper Cretaceous and 

Paleocene (Midway) beds, which form an important 

part of the body of Crowleys Ridge in southeastern 

Missouri, are monoclinal, dipping gently to the southeast into the synclinal basin formed by the downwarping of the Gulf Embayment region. Data furnished 

by Farrar and McManamy (1937 geol. map, pi. 9) indicate that the southeast dip of the Cretaceous-Paleocene 

contact in the Bloomfield area in Stoddard County is 

between 40 and 45 feet to the mile. The map cited shows 

a broad upwarp accompanied by minor faulting in the 

Bloomfield area, but the data presented seem to justify 

an estimated regional dip of the Cretaceous-Paleocene

contact to the southeast of 35 or 40 feet to the mile. As 

the beds below and above the contact are nearly parallel 

to each other the regional dip of the Cretaceous, Paleocene, and Eocene beds to the southeast may be assumed 

to be about the same as that of the contact.

Originally, and as late as late Tertiary (Pliocene) 

time, the Cretaceous and Paleocene strata of Crowleys 

Ridge in southeastern Missouri were physically continuous southward through the Gulf Embayment with 

the beds of the same age in Mississippi. Their physical 

continuity was broken in Pleistocene time by erosion, 

first by the Ohio River before the capture of the Mississippi, and later by the combined waters of the Ohio 

and the Mississippi, leaving the Cretaceous and Paleocene formations at elevated positions in the Crowleys 

Ridge upland.

FOSSIL LOCALITIES

With the exception of one collection (TJSGS 16221), 

all the Cretaceous fossils from Missouri described or 

mentioned in this paper were obtained from the Owl 

Creek formation at the localities in Stoddard and Scott 

Counties listed below; the Cretaceous fossils in this 

collection (USGS 16221) were found in the basal bed 

of the Clayton formation, into which they had been 

incorporated by mechanical reworking from the underlying Owl Creek formation. The collection bearing the 

number USGS 19088 consisted of one incomplete internal mold of the ammonite, Sphenodiscus pl&urisepta 

(Conrad), which was collected by Edison Shrum of 

Advance, Mo., and donated to the United States Geological Survey, through Willard Farrar of the Missouri 

Survey. (See fig. 21.)

The one collection (USGS 16221) from the basal bed 

of the Clayton formation, previously mentioned, was 

made by F. E. Matthes in June 1932, at the locality near 

Ardeola station, the description of which is given below ; the bed is reported to be at an altitude of 430 feet, 

and about 110 feet above the base of the slope. This is 

the collection that led to the discovery of the McNairy 

sand, and the Owl Creek formation of the Cretaceous, 

and the Clayton and Porters Creek formations of the 

Paleocene, in southeastern Missouri. All the fossils specifically identified in this collection are Owl Creek 

(Upper Cretaceous) species derived by mechanical reworking from the underlying Owl Creek formation. 

Some of the genera that are not identified as to species 

may be indigenous to the Clayton formation. Typical 

Clayton (Midway) fossils were later found in the 

oolitic clay, associated with the reworked Cretaceous 

fossils.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 103

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104 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Cretaceous fossil localities in Stoddard and Scott Counties; 

numbers are the collection numbers of the U. 8. Geological 

Survey

TJSGS 16429, 16452, 16454, 19088. Road cut and ditch on the 

southeast-facing slope of Crowleys Ridge, 0.35 mile northwest of Ardeola station in SWiNWi sec. 10, T. 27 N'., R. 11E., 

Stoddard County, Mo.; from the Owl Creek formation. 

Collectors Willard Farrai*, H. S. McQueen, and L. W. Stephenson, March 1933; Farrar and Mr. Field, July 1933; 

Edison Shrum, 1940.

TJSGS 16430. Road ditch about 150 feet south of road junction 

near the southeast corner of SEi sec. 4, T. 27 N., R. 11 E., 

about 1 mile northwest of Ardeola station, Stoddard County, 

Mo.

Collectors Willard Farrar, H. S. McQueen, L. W. Stephenson, March 19, 1933.

TJSGS 19090. Ditch on east side of north-south road one-eighth 

mile south of road junction, 1.4 miles west by slightly 

south of Ardeola station, in center of east line of NEiSE'i 

see. 8, T. 27 N., R. 11 E., Stoddard County, Mo.; ferruginous, 

finely micaceous sandstone.

Collectors H. S. McQueen, D. R. Stewart, Lyle McManamy, 

L. W. Stephenson, W. H. Monroe, April 4, 1938.

TJSGS 16451. Left bank of a dry branch 300 feet downstream 

from a road crossing, 2.1 miles southwest of Ardeola station, in center SiNWiSEj sec. 17, T. 27 N., R. 11 E., Stoddard County, Mo.; from just below Owl Creek-Clayton 

contact 

Collectors Willard Farrar, Mr. Field, July 4, 1933.

TJSGS 16597. TJ. S. Highway 61, one-fourth mile northeast of 

junction with secondary road near benchmark 374,1.6 miles 

southwest of Benton, 16 feet below highway on east side, in 

NEiSWiNEi sec. 23, T. 28 N., R. 13 E., Scott County, Mo.; 

Owl Creek formation just below contact with Clayton formation. Altitude, 360± feet. 

Collector Willard Farrar, 1934.

TJSGS 16598. Gully northeast of house on Fullenwider farm 

1 mile southeast of Oran, in NWiSWiNEi sec. 20, T. 28 N.f 

R. 13 E., Scott County, Mo.; from uppermost bed of Owl 

Greet formation. Altitude 410± feet. 

Collector Willard Farrar, 1934.

TJSGS 16453. Loose on slope on Fullenwider farm 1 mile southeast of Oran, in NWiSWiNEi sec. 20, T. 28 N., R. 13 E., 

Scott County, Mo.; this specimen must have been derived 

by weathering or erosion from the Owl Creek formation. 

Collector Willard Farrar, July 1933.

The distribution of the fossils collected and identified 

from the Owl Creek formation in Stoddard and Scott 

Counties is shown in the accompanying table.

Distribution of Owl Creek fossils in Stoddard and Scott Counties, Mo.

Numbers at heads of columns are collection numbers of the United States Geological Survey. Descriptions of localities are given above. Each column at right Indicates

the fossils from one locality. The asterisk Indicates species restricted to the Owl Creek formation]

Porifera (Spongiae): 

Cliona microtuberum Stephenson- _______ _____ _ _ ___ ___ ________ -___

Annelida (Chaetopoda) : 

Serpula sp___ __ __ ___ _ ______ _ __ __ ___ ________ _ __

Mollusca: 

Pelecypoda:

sp___ — _ _ ______ _________ ____ _ ___ __ _ ___ _-_ _

Nuculana longifrons (Conrad) _________ ____ __ _ _ _________ _ ___

sp. (smooth) _____ _____ _ ______ _________-_--_---

*Pinna laqueata Conrad. _____ _______ _ _ _ ________ _ _ _ ___ _

Exogyra costata Say (juvenile) ___ _________ __ ____ ____

eufaulensis Gabb__ _______ _ __ _____ ___

*Pecten (Camptonectes) bubonis Stephenson. ___ _____ _______

Lima acutilineata (Conrad). _ ______ _____ ____ __ _____ _____ __

* microstriata Stephenson, n. sp ___ __ _ __ __ _ _______-----

?sp__ ___ _ _ _ _ _ _ _ __ _ _ .._ _ __ _ _ _ _

Liovistha vrotexta (Conrad) _______________ __ ___.

Stoddard County

16429, 

16452 

16454, 

19088,

X 

X

X 

X 

X 

X 

X 

X

X 

X 

X 

X

X 

X 

X 

X

X 

X

16430

X 

X 

X

X 

X

X 

X

X

19090

X 

X

X 

X

X 

X 

X

X

X 

X

X 

X 

X

X 

X

X 

X 

X

16451

X 

X

X 

X 

X

X 

X

X 

X

X 

X

Scott County

16453

X

16597

X 

X

16598

X 

X
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 

Distribution of Owl Creek fossils in Stoddard and Scott Counties, Mo.—Continued

105

Mollusca — Continued 

Pelecypods — Continued

*Crassatella vadosa ripleyana (Conrad). __ _ __ ______ ___ _____ _ _ __

*Scambula perplana Conrad _ _ _____ _ ____ _ ___ __ ___ _ ___

(Pachycardium) spillmani Conrad___ _____________________ _ _ ___

*Cyprimeria alta Conrad _ _ ____ ___ _____ _______ ________ __ ___

Tellina buboana Stephenson, n. sp_________ ____ _ _____ _______ _ ___

Corbula (several species) __ _ ___ _________ _____ ______ _ __ _ _ _

*Panope monmouthensis Gardner _ ___ _ __________ _____ ___ _ ___

*Gastrochaena ripleyana Stephenson_____ __ _______ ___ _ ____ _ _

Goniochasmal sp _ __ _ ____ _____ _ _ _ _ __________ _ _ __ _____

Gastropoda: 

*Pseudomalaxis pateriformis Stephenson, n. sp_____ ___ ____ ___ _______

Polinices rectilabrum (Conrad) ___ _ ______ _____ _ ____ ___

Turritella tippana Conrad _ _____ ____ _ ___ ______ ____

*Helicaulax formosa Stephenson, n. sp__ ______ ____ ____ ______ ____

_Y*k

*Morea transenna Stephenson, n. sp____ ___ _____ _ ____ _____

Fusinusl sp. A_ ____ _ _ ______ ______ _____ ___ __ _ __ ________

?sp. B _ _ __ _ ___ _ _ ____ ______ _ _______________ -_._

*Liopeplum rugosum Stephenson, n. sp. ___________ _______ _____ ______

Drillutasp _ _ ____ ______ _ __ ____ ___ ___ ___________________

Volutomorpha? spp _ _ _____ _____ _ _____________ _ _ __ ______

Caveola sp ___ __ _ __________ ______ ____ ________ _________ ___

*Eoacteon lintea (Conrad), n. gen ____ ______________________ _ _______

*Bullopsis cretacea (Conrad) _ _ ______ ____ _________ ___ _ _ _______

Cylichnasp.- ___ __ _ _ __ ________________________ ___ ________

Cephalopoda: 

*Baculites carinatus Morton. ____ ___________ ___ ___________________

*Discoscaphites iris (Conrad)__ _ ____ ___________________ ___________

Stoddard County

16429, 

16452 

16454, 

19088,

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X

X 

X

X 

X

?

X 

X

X 

X

16430

X

X 

X

X 

X

? 

X 

X

f

X 

X

19090

X 

X 

X 

X 

X

X 

X

X 

X 

X 

X 

X

X 

X

X 

X 

X

X 

X 

X

X 

X 

X

X 

X 

X 

X 

X 

X

X

16451

X 

X

X 

X 

X 

X

X

X 

X

X 

X

X 

X

X 

X

X 

X

X

Scott County

16453 16597

X

?

X

X 

X

16598

X 

X

X

X 

X

X

CORRELATION

The table of distribution lists 56 identified species 

of marine organisms, mostly mollusks, from the Owl 

Creek formation of southeastern Missouri. With a few 

exceptions the species listed have been previously recorded from the Owl Creek formation of Mississippi or 

from beds of Owl Creek age in the Gulf region. As 

known at present 28 of the named species are restricted 

to the Owl Creek formation or to beds of that age in 

the Gulf region. The other 28 have longer ranges, 

occurring in deposits older than the Owl Creek formation; many of them are in the Kipley formation, which 

underlies the typical Owl Creek in Mississippi. The 

Owl Creek age of the marine fossiliferous beds forming 

the uppermost part of the Cretaceous sections above the 

McNairy sand in southeast Missouri is thus firmly 

established.

The McNairy sand, as it is developed in the head 

region of the Mississippi Embayment, is a shallow 

water, possibly in part nonmarine, f acies of the marine 

Kipley formation in Mississippi. A few fossil leaves 

have been found in the McNairy sand in Tennessee, but 

the formation has yielded no marine organisms.
106 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

SYSTEMATIC DESCRIPTIONS

Phylum PORIFERA

Class SPONGIAE 

Order MONACTINELLIDA

Family CLIONIDAE

Genus CLIONA Grant, 1826

Cliona microtuberum Stephenson

Plate 15, figures 1, 2

1941. Cliona microtuberum Stephenson, Tex. Univ. Pub. 4101, 

p. 54, pi. 3, figs 1-5; pi. 5, figs. 1, 2.

Two specimens from the collection 2.1 miles southwest 

of Ardeola, (USGS 16451), one an undetermined bivalve and the other a gastropod (Turritella sp.) preserve the ferruginous casts of a boring sponge, here 

referred to Cliona microtuberum, Stephenson. In size, 

shape, pattern of distribution, and finely stippled 

surface, these casts appear to be essentially like those 

of the holotype from the Corsicana marl of Texas. 

The original material composing the casts, which presumably was phosphatic, has been replaced by hematitic 

oxide of iron. The casts are so densely crowded as to 

preserve the shape of the shells in which the borings 

were made. There is evidence of casts of slender, 

smooth, intercommunicating cavities, intermingled 

with the Cliona casts. These appear to be like the 

problematical casts (of a sponge?) associated with the 

holotype from the Corsicana marl and with one of the 

paratypes from the Kemp clay of Texas. Casts of 

/Serpula-likQ tubes are attached to the gastropod specimen, apparently to the outside of the original shell.

Types.—Holotype, USNM 76266; paratype, USNM 7626S, 

from the Corsicana marl, Texas. Paratype, USNM 76267, from 

the Kemp clay, Texas. Paratype, USNM 76270, from the 

Prairie Bluff chalk, Alabama. Two plesiotypes, USGS 16451, 

USNM 128081, from the Owl Creek formation, 2.1 miles southr 

west of Ardeola, Stoddard County, Mo.

Range.—Owl Creek formation and Prairie Bluff chalk of 

eastern Gulf region; Corsicana marl and Kemp clay.of Texas. 

Phosphatic casts of boring sponges, some of them perhaps 

belonging to Cliona microtuberum, are common in the upper 

part of the Cretaceous series in the Atlantic and Gulf Coastal 

Plain.

Phylum ANNELIDA

Class CHAETOPODA

Family SERPULIDAE

Genus SERPULA Linne, 1758

Serpula sp.

Ferruginous casts of tubes that appear to pertain 

to the genus Serpula Linne are present in two of the 

collections, USGS 16451 and 19090. The tubes as 

preserved are short, taper a little more rapidly than 

is typical of tubes of this genus, and are irregular in

their longitudinal alinement. USNM 128122 (on Tutritella sp.) and USNM 128082.

Genus HAMULUS Morton, 1934

Hamulus squamosus Gabb

Plate 15, figure 3

1860. Hamulus squam&sus Gabb, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 4, p. 398, pi. 68,, fig. 45. (For synonymy 

through 1941, see Tex. Univ. Pub. 4101, 1941, p. 60.)

Add:

1940. Hamulus squamosus Gabb. Stephenson and Monroe, 

Miss. State Geol. Survey Bull. 40, p. 288, pi. 14, fig. 4. 

(Illustration only.)

This species is represented in the Owl Creek formation of southeastern Missouri by several incompletely 

preserved imprints and internal molds of tubes (USGS 

19090). The tubes are short, evenly curved, rather 

rapidly expanding, and ornamented with 6 longitudinal ribs. Two of the ribs on opposite sides of the tube, 

and lying in the plane of curvature, are expanded to 

form prominent winglike extensions. The other 4 ribs 

are narrow, low, rather sharp, with small irregular 

nodes along the crest; they form 2 narrowly parallel 

pairs, 1 pair on one side, and the other on the opposite 

side of the tube, between the 2 expanded ribs.

Types.—Gabb's original material should be preserved in the 

Academy of Natural Sciences of Philadelphia, but it is not 

included in the Academy's list of Cretaceous types, and presumably is lost. Plesiotype from Missouri, USGS 190QO, 

USNM 128083.

Range.—Geographic, Gulf Coastal Plain; geologic, Upper 

Cretaceous, through the zones of Exogyra ponderosa and E. 

costata.

Phylum MOLLUSCA

Class PELECYPODA

Order PRIONODESMACEA

Superfamily NUCULACEA

Family NUCULIDAE

Genus NUCULA Lamarck, 1799

Nucula percrassa Conrad

Plate 15, figures 4-7

1858. Nucula percrassa Conrad, Acad. Nat. Sci. Phila. Jour., 2d

ser., v. 3, p. 327, pi. 35, fig. 4. 

1876. Nucula percrassa Conrad. Gabb, Acad. Nat. Sci. Phila.

Proc. for 3876, v. 28, p. 318. 

1926. Nucula percrassa Conrad. Wade, U. S. Geol. Survey Prof.

Paper 137, p. 39, pi. 8, figs. 1-4. 

1931. Nucula percrassa Conrad. Roberts, Ky. Geol. Survey, ser.

6, v. 36, p. 404, pi. 68, figs. 1, 2.

One incomplete internal mold from southeastern Missouri (USGS 19090) is here referred to Nucula percrassa Conrad. It represents the anterior part of a 

juvenile right valve. It appears to be identical with 

young shells of the species from Owl Creek, Miss., the 

type locality. Well-preserved shells of the species are
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 107

abundant at the Owl Creek locality, many of them having both valves intact. Shell thick, plump, elongate, 

inequilateral, equivalve, with greatest inflation below 

the beak a little above the midheight. Beaks prominent, 

opisthogyrate, closely approximate, situated slightly 

more than two-thirds the length from the anterior extremity. On most of the adult specimens from the Owl 

Creek formation in Mississippi the lower posterior slope 

of the shell back of the midlength bends in more or less 

steeply to the ventral margin. Although the species is 

common in the Bipley formation, which underlies the 

typical Owl Creek, at some localities the shells, even 

large ones, show little or none of the posterior inbending; however, in the Coon Creek tongue of the Ripley 

formation, a basal Ripley zone (Wade 1926, p. 39), the 

inbending is about as strongly developed in some shells 

as it is in the Owl Creek shells. Apparently this feature 

is a premature senile character caused by some local inhibiting environmental condition. Escutcheon broad, 

relatively short, distinctly outlined, slightly sunken. 

Lunule long, narrower than the escutcheon, faintly outlined, anterior margin sharply rounded, ventral margin broadly rounded, posterior margin subangular at 

the extremity. Surface marked with numerous, closely 

spaced, weak radial ribs, and irregular, concentric 

growth lines and ridges.

Dimensions of the figured shell from Owl Creek, 

Miss.: Length 31.6 mm, height 19 mm, thickness 18.7 

mm.

Hinge taxodont, teeth numerous, sharp, in 2 unequal 

series; in adults about 11 teeth in the posterior series, 

and about 30 in the anterior series; 1 prominent cardinal tooth in the left valve below the beak is oblique 

forward just back of the resilifer; a corresponding 

socket in the right valve is back of the resilifer.

Resilifer deeply submerged, protruding inward, 

spoon-shaped, narrow, oblique forward. Adductor 

scars small, sunken, pallial line entire. Inner margin 

finely crenulated. Inner surface nacreous.

Weller (190T, p. 369) includes in the synonymy of 

Nuoula percrassa Conrad the specimens described and 

figured by Whitfield (1885, p. 102, pi. 11, figs. 4-6) 

under that name, and also includes the two species Leda 

slacMana Gabb (p. 103) and Donax fordii Conrad 

(p. 171). All of these as originally described and illustrated, including those figured by Weller, appear to be 

different in form and seem obviously to belong to species 

other than Nucula percrassa.

Types.—Holotype, Academy of Natural Sciences, Philadelphia. Two topotypes from Owl Creek, Miss., USGS 707, USNM 

128084.; plesiotype from southeastern Missouri, USGS 19090, 

USNM 128085.

Range.,—Ripley and Owl Creek formations and beds of corresponding age (Exogyra costata zone) in the Gulf Coastal 

Plain.

Nucula sp.

Two small, poorly preserved internal molds of Nucula, one a left and the other a right valve, are present 

in the collection from a mile northwest of Ardeola station (USGS 16430, USNM 128086). They appear to 

represent a species other than Nucula percrassa Conrad.

Family NUCULANIDAE

Genus NTJCULANA Link, 1807, sensu lato

Nuculana longifrons (Conrad)

Plate 15, figures 18, 19

1860. Leda longifrons Conrad, Acad. Nat. Sci. Phila. Jour., 2d 

ser., v. 4, p. 281, pi. 46, fig. 18.

(For synonymy through 1941, see Tex. Univ. Pub. 4101, 

1941, p. 78.)

The species Nuculana longifrons (Conrad) is represented in the collections from southeastern Missouri 

by 3 specimens, 1 from the locality 0.35 mile northwest 

of Ardeola (USGS 16429) and 2 from the locality 1.4 

miles west by slightly south of Ardeola (USGS 19090). 

Our collections contain well-preserved shells of the 

species from the Owl Creek formation in Mississippi, 

but apparently the individuals are not numerous.

The species is rather large for the genus. Shell thin, 

elongate, compressed, relatively high, smooth, inequilateral, equivalve; posterior slope somewhat flattened. 

Beak small, nonprominent, incurved, approximate, situated one-third the length of the shell from the anterior extremity. Anterior and posterior margins 

rounded narrower than a semicircle, the posterior one 

slightly truncated; dorsal and ventral margins nearly 

straight, subparallel. Hinge narrow with numerous 

fine teeth in two series, the posterior series longer than 

the anterior. Pallial sinus short, triangular. Inner 

margin smooth.

Dimensions of the figured internal mold of a right 

valve from Missouri (pi. 15, fig. 19): Length 16 mm, 

height 8.3 mm, convexity about 2 mm.

Types.—Holotype, Academy of Natural Sciences, Philadelphia. Plesiotype from the Owl Creek formation of southeastern 

Missouri, USGS 19090, USNM 128087; plesiotype from Owl 

Creek formation, Mississippi, USGS 707, USNM 128088.

Range.—The species has a long geologic range through the 

zones of Exogyra ponderosa and E. eostata, and a geographic 

range throughout the length of the Atlantic and Gulf Coastal 

Plain of the United States.

Nuculana sp.

Poorly preserved internal molds of small shells of 

Nuculana Link were found at the locality 0.35 mile 

northwest of Ardeola (USGS 16429, USNM 128089),
108 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

and at the locality a mile northwest of Ardeola (USGS 

16430, USNM 128090). At the locality 1.4 miles west 

by south of Ardeola (USGS 19090, USNM 128091), a 

small internal mold was found on which are the faint 

impressions of nonconcentric ribs that cross the concentric lines of growth obliquely; this probably pertains 

to an undescribed species.

Superfamily PARAILELODONTACEA

Family PARALLELODONTIDAE

Genus NEMODON Conrad, 1869

Nemodon eufaulensis (Gabb)

Plate 15, figures 8-12

1860. Area (Macrodon) eufalensis Gabb, Acad. Nat. Sci. Phila. 

Jour., 2d ser., v. 4, p. 398, pi. 68, fig. 39.

1916. Nemodon eufalensis (Gabb). Gardner, Md. Geol. Survey, 

Upper Cretaceous [Maryland], in W. B. Clark and others, p. 525, pi. 20, figs. 3, 4.

1926. Nemodon eufaulensis (Gabb). Wade, U. S. Geol. Survey 

Prof. Paper 137, p. 42, pi. 8, figs. 17,18.

This species is represented in the collections from 

southeastern Missouri by several internal molds and by 

one small external mold, from three localities (USGS 

16430, 16452, 19090). The description is based mainly 

on complete shells from Owl Creek, Miss., and Eufaula, 

Ala. Shell small, elongate, moderately inflated, greatest inflation above midheight just below the beak, 

strongly inequilateral, equivalve. Umbonal ridge 

rounded; umbonal region broad; beaks nonprominent, 

incurved, approximate, prosogyrate, somewhat variable 

in position, ranging from 0.26 to 0.33 the length of the 

shell from the anterior extremity; a broad shallow depression extends radially from the beak to the ventral 

margin, centering slightly forward of midlength. Dorsal margin long, straight; anterior margin evenly 

rounded, meeting the hinge line at an approximate right 

angle; ventral margin long, nearly straight to broadly 

concave, subparallel to hinge line; posterior margin 

sharply rounded below, straight and inclined strongly 

forward above. Surface ornamented with numerous, 

closely spaced, flattened, nonprominent, radial ribs, 

those on the umbonal ridge and on the posterior and 

anterior slopes coarsest and showing a tendency to form 

pairs; concentric growth lines fine, sharply impressed.

Dimensions of a typical left valve from Eufaula, 

Ala.: Length 17 mm, height 7.8 mm, convexity about 

2.5 mm. The shells may attain a length of 25 mm or 

more.

Hinge long, narrow, straight. Teeth long, narrow, 

nearly parallel to hinge line, all finely striated on both 

sides at right angles to hinge plate; three anterior teeth, 

the lowest one shortest; posterior teeth much longer, the 

middle one longest. Area amphidetic, long, narrow, 

smooth in front of beak and scored with 2 or 3 long,

narrow, oblique ligamental grooves back of beak. Adductor scars rather large, nearly flush with inner surface, pallial line entire; inner margin smooth; inner 

surface has weak radial lines.

Types.—Holotype, from Eufaula, Ala., Academy of Natural 

Sciences, Philadelphia. Two plesiotypes (=topotypes) from 

Eufaula, Ala., USNM 18830; 1 plesiotype from southeastern 

Missouri, USGS 19090, USNM 128092.

Range.—In the Gulf region the range of the species is through 

the Ripley and Owl Creek formations and beds of corresponding 

age (Maestrichtian). An apparently authentic specimen of the 

species is recorded by Gardner (1916, p. 525, pi. 20, figs. 3, 4) 

from the Monmouth formation of Maryland. Whitfield's (1885. 

p. 83, pi. 12, figs. 3-5), and Weller's (1907, p. 385, pi. 30, figs. 

8-11) figured specimens from New Jersey, referred to this 

species, are internal molds that do not satisfactorily show specific characters; the one shown in Weller's figure 11 is from 

the Vincentown sand, which is now known to be of Eocene age; 

this specimen is probably not a Nemodon.

Superfamily GLYCYMERACEA

Family GLYCYHERIDAE

Genus GIYCYMERIS Da Costa, 1778

Glycymeris rotundata (Gabb)

Plate 15, figures 13-17

1860. Aceinaea rotundata Gabb, Acad. Nat. Sci. Phila. Jour., 2<I 

ser., v. 4, p. 396, pi. 68, fig. 33. (See Stephenson, 1941, 

p. 84.)

The species Glycymeris rotundata (Gabb) is represented in southeastern Missouri at three localities by 

internal molds (USGS 16429, 16451, 19090), only one 

of which is fairly well preserved (pi. 15, fig. 17). Two 

of the molds (USGS 19090) pertain to adult individuals. Beautifully preserved shells are present in the 

Eipley formation at the type locality at Eufaula, Ala., 

in the Owl Creek formation at Owl Creek, Miss., and 

at other localities in these formations in the Gulf region. The description is based on well-preserved shells 

from Eufaula, Ala., the type locality, and from Owl 

Creek, Miss. Several species of Glycymeris closely related to 6r. rotundata (Gabb) have been recorded from 

the Atlantic and Gulf Coastal Plain; some of them may 

prove to be identical with Gabb's species.

Shell of medium size, thick, moderately inflated, subcircular in outline, nearly equilateral, equivalve. Some 

shells are faintly oblique in the posteroventral direction. Beaks nonprominent, direct, incurved, approximately central. Surface weakly ornamented with 

numerous flattish radiating ribs of different widths, 

narrowest on the anterior slope, widest on the posterior 

slope.

Dimensions of the adult right valve shown in plate 15, 

figures 13,14: Length 44 mm, height 43.5 mm, convexity 

18 mm. The small internal mold from Missouri (pi. 15, 

fig. 17) measures: Length 21.5 mm, height 20 mm, 

convexity, about 5 mm.
OWL CREEK FOSSILS FEOM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 109

Cardinal area amphidetic, elongate triangular, with 

longest edge at top of hinge, bearing in adults 5 or 6 

chevron-shaped, symmetrically divided ligamental 

grooves. Hinge plate strongly arched, transected above 

by the lower straight edge of the cardinal area. In 

adults 8 or 10 small, short, transverse teeth border 

the central part of the cardinal area; on either side of 

this central series are strong transverse, slightly angulated teeth, the anterior ones numbering 8 or 10 and the 

posterior' ones 10 or 12. Adductor scars subtriangular, 

the anterior scar slightly the larger, both bordered on 

the inner side by a weak radiating carina. A small, 

elongate muscle scar, one under each end of the hinge 

plate, is a feature that appears to be common to all the 

species of Glycymeris. Pallial line simple. Inner margin strongly crenulated.

Types.—Holotype, from Eufaula, Ala., Academy of Natural 

Sciences, Philadelphia. Plesiotypes from Owl Creek, Miss. 

USGS 707, USNM 128093, and USGS 594, USNM 21681. Plesiotypes from Missouri, USGS 16429, USNM 128094; and USGS 

19090, USNM 128095.

Range.—The species ranges at least through the Ripley and 

Owl Creek formations (Maestrichtian) and beds of corresponding age in the Gulf Coastal Plain.

Family NOETIDAE

Genus BREVIARCA Conrad, 1872

Breviarca? sp.

One small internal mold (USGS 16452) appears to 

have the form of Br&marca Conrad, but the hinge is 

not preserved and the identification is questioned. 

Shell strongly convex, beak prominent, dorsal slopes 

steep. Dimensions: Length 9 mm, height 6.8 mm, convexity about 3.5 mm. USNM 128096.

Family CTJCULLAEIDAE

Genus IDONEARCA Conrad, 1862

Idonearca capax (Conrad)

Plate 15, figures 20-26

1858. Cucullaea capax Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 328, pi. 35, fig. 2.

1858. Cucullaea tippana Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 328, pi. 35, fig. 1. [Younger stage of 

G. capax Conrad.]

1862. Idonearca capax (Conrad). Conrad, Acad. Nat. Sci. 

Phila. Proc., v. 14, p. 289.

1872. Idonearca capax (Conrad). Conrad, Acad. Nat. Sci.

Phila. Proc., v. 24, p. 54, pi. 2, fig. 2.

?1876. Idonearca alabamensis Gabb, Acad. Nat. Sci. Phila. 

Proc., v. 28, p. 315.

1898. Idonearca, tippana Conrad. Ball, Wagner Free Inst. 

Sci. Phila. Trans., v. 3, pt. 3, p. 603. (Designated genotype of Idonearcfj, Conrad.)

1916. Cucullaea vulgaris Morton. Gardner, Md. Geol. Survey, 

Upper Cretaceous [Maryland], in W. B. Clark and 

others, p. 529, pi. 20, figs. 8, 9; pi. 21, figs. 1, 2.

1930. Cucullaea (Idonearca) tippana (Conrad). Stewart, 

Acad. Nat. Sci. Phila. Spec. Pub. no. 3, p. 74.

1940. Idonearca capax (Conrad). Stephenson and Monroe, 

Miss. State Geol. Survey Bull. 40, p. 280, pi. 10, figs. 

6, 7. (Illustrations only.)

1941. Idonearca capax (Conrad). Stephenson, Tex. Univ. Pub.

4101, p. 92, pi. 11, figs. 1-4; pi. 12, fig. 3. 

1950. Cucullaea (Idonearca) capax Conrad. Nicol, Jour.

Paleontology, v. 24, no. 1, p. 93, pi. 21, fig. 9. 

1954. Idonearca Conrad. Nicol, Jour. Paleontology, v. 28, no.

1, p. 97. Mentions Cucullaea tippana Conrad (emended

by Stephenson, C. capax Conrad) as genotype of

Idonearca, designated by Dall, 1898.

The synonymy given by Stephenson (1941, p. 92) is 

not as complete as it should have been, for which reason a more complete synonymy is given here.

Emphasis is given to the fact that Cucullaea tippana 

Conrad is a young stage of G. capax Conrad, and not 

an independent species. The two names were introduced by Conrad (1858, p. 328) on the same page. His 

description of G. capax pertains to an adult form of the 

species, and appears ahead of that of C. tippana on the 

page. Cucullaea capa% is therefore the name that 

should have been used by Dall (1898, p. 603) when he 

designated the genotype of Idonearca.

Internal and external molds show the unmistakable 

presence of Idonearca capax (Conrad) at three localities in the Owl Creek formation of southeastern Missouri (USGS 16451,16452,19090). The available material includes early, medial, and adult stages of 

growth.

The species has been described in considerable detail 

in a former treatise (Stephenson, 1941, p. 92, pi. 11, figs. 

1-4; pi. 12, fig. 3) and need not be redescribed here. 

One feature not mentioned in that description is a narrow, low sharp ridge midway of the posterodorsal slope 

of the right valve, extending from the beak to the 

middle of the posterodorsal margin; this ridge is not 

matched by a corresponding ridge in the left valve 

(pi. 15, fig. 21).

Gardner (1916, p. 529, pi. 20, figs. 8, 9; pi. 21, figs. 

1, 2) used specimens from Owl Creek, Miss, to illustrate 

her species Cucullaea vulgaris Morton. Shells from the 

Monmouth formation in the National Museum collections are very closely related to Idonearca capax Conrad, and may be identical but they are badly crushed 

and cannot be satisfactorily identified.

Types.—Holotype, Academy of Natural Sciences, Philadelphia. 

One plesiotype (= topotype) from Owl Creek, Miss. (Stephenson, 1941, pi. 11, figs. 3, 4, USGS 707, USNM 76356). Two 

plesiotypes (= topotypes) from the same source, USGS 707, 

USNM 128097; 1 is the rubber internal mold of an adult topotype. Two plesiotypes from southeastern Missouri, USGS 19090, 

USNM 128098.
110 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Range.—Idonearca capax is common in the Owl Creek formation of southeastern Missouri and northern Mississippi, and in 

the Prairie Bluff chalk of Mississippi and Alabama. The occurrence of the species in formations older than the Owl Creek has 

not been satisfactorily confirmed.

Superfamily PTEBJACEA

Family PINNIDAE

Genus PINNA Linne, 1758

Pinna laqueata Conrad

Plate 16, figures 10-12

1858. Pinna laqueata Conrad, Acad. Nat. Sci. Phila. Jour., 2d 

ser., v. 3, p. 328.

Conrad based this species on a fragment from Owl 

Creek, Tippah County, Miss. His description is very 

brief and without an illustration. The specimen is 

probably lost as it is not listed by Johnson (1905) as 

preserved in the collection of the Academy of Natural 

Sciences of Philadelphia. Although there can be no 

proof that the large shells from Owl Creek here figured 

(pi. 16, figs. 10, 11) are specifically identical with the 

fragment recorded by Conrad there would seem to be a 

reasonable assumption that they belong to the same 

species. Conrad described the species as follows: "A 

fragment—ventricose, with eleven prominent, slender 

ribs; interstices concave."

One fragment from the Owl Creek formation of 

Missouri is referred to {Pinna laqueata Conrad '(USGS 

16452). It represents a part of the small end of the 

shell and includes an internal and an external mold. 

The latter bears nine nearly straight, narrow longitudinal ribs, separated by wider interspaces, on the 

upper part, with several ribs of irregular trend on the 

lower slope. The internal mold appears to expand 

rather rapidly. The ribbing on this specimen (pi. 16, 

fig. 12) may be compared with that on the specimen 

from Owl Creek, Miss., shown in plate 16, figure 11, 

which is believed to be a topotype.

The large shell from Owl Creek (USGS 707) is thin, 

elongate, pointed anteriorly, expanding posteriorly, 

moderately inflated, subcircular in cross section at the 

small end, becoming quadrate to diamond shaped in the 

medial part, and becoming compressed with long axis 

vertical, toward the posterior end. The upper surface 

from a little below the middle to the dorsal margin 

bears nine nearly straight, narrow, round-crested ribs 

with shallow, broad, concave interspaces; these ribs diverge slightly and increase gradually in strength front 

to rear; the lower slope of the shell bears a series of 

ribs of somewhat irregular trend and cross section, but 

all bend upward slightly as they pass from front to 

rear. The beak is terminal at the front. Faint curved 

lines on the upper slope back of the midlength mark

the position of the abductor muscle attachment. 

Other topotypes in the National Museum collection 

show that the number of straight ribs on the upper surface may range from 9 to 11. The ligamental groove is 

not observable but it must be paper thin and probably 

is about one-third the length of the shell.

Dimensions of the figured topotype: Length 225 + 

inm, height about 82 mm, maximum thickness 27 mm; 

the actual length is somewhat greater than indicated, 

as neither the anterior nor the posterior end is complete.

The shells from the Merchantville clay and from the 

Woodbury clay, New Jersey, referred by Whitfield 

(1885, p. 81) and by Weller (1907, p. 419) to Pinna 

laqueata Conrad, although closely related, lack irregular, coarse ribbing on the lower slope of the shell as 

shown on the illustrations, and should probably be regarded as specifically distinct. The same may be said 

of the fragment described by Gardner (1916-, p. 545) 

from the Matawan formation, Delaware; some of the 

straight ribs on this specimen bear fine tubercles, in contrast to the corresponding smooth ribs on P. laqueata.

Types.—Holotype, whereabouts unknown. Topotype from 

Owl Creek, Miss., USGS 707, USNM 128100; topotype from Owl 

Creek (USGS 707, USNM 128090) ; plesiotype from the Owl 

Creek formation of Missouri, USGS 16452, USNM 128101.

Range.—So far as is known from satisfactorily identified 

specimens the species is restricted to the Owl Creek formation 

of the Gulf Embayment area.

Superfamily FTEBIACEA

Family PTERIIDAE 

Genus TENTTIPTERIA Stephenson, n. gen.

Type species: Inoceramus argenteus Conrad.

Etymology.—Latin tenuis, thin; genus Pteria.

The species here made the type of the new genus 

Tenuipteria has been referred heretofore to the genus 

Inoceramus Sowerby. However, the series of pits on 

the ligamental area lacks the uniformity in size and 

spacing that characterizes Sowerby's genus. Instead 

the narrow ligamental area of Tenuipteria bears three 

or more pits of unequal size and spacing, some of them 

more or less elongated. The beaks are nearly terminal. 

The right valve possesses a small Pteria-like ear, and 

the left valve has a still smaller anterior earlike extension. The shell is nacreous, thin, of medium size, 

strongly inequilateral, strongly inequivalve, the left 

valve much more convex than the right. Both valves 

are ornamented with numerous radiating ribs, those 

on the left valve being weak and tending to fade out 

on the anterodorsal, posterodorsal and ventral slopes; 

the ribs on the right valve are moderately strong on 

the main part of the shell, but fade out and disappear 

on the posterodorsal slope and become very weak on 

the anterodorsal slope.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 111

Tenuipteria argentea (Conrad) 

Plate 16, figures 4-9

1858. Inoceramus argenteus Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 329, pi. 34, fig. 16. 

1858. Inoceramus costellatus Conrad, Acad. Nat. Sci. Phila.

Jour., 2d ser., v. 3, p. 329, pi. 34, fig. 12. 

1940. Inoceramus argenteus Conrad.- Stephenson and Monroe,

Miss. State Geol. Survey Bull. 40, p. 280, pi. 10, figs. 8r

9. (Illustrations only.) '

The species Tenuipteria argentea (Conrad) is represented by meager poorly preserved material from three 

localities in southeastern Missouri (USGS 16451,16452, 

and 19090). However, the specimens, such as they are, 

possess sufficient characteristic features to permit positive identification. The description is based mainly on 

well-preserved topotypes from Owl Creek, Miss.

Shell of medium size, thin, nacreous, strongly inequilateral, strongly inequivalve, the left valve being much 

more convex and higher than the right. The beaks are 

nearly terminal and are slightly prosogyrate. The left 

valve is plumply convex anteriorly and rounds broadly 

to tl\e ventral and posterior margins; the right is only 

moderately inflated in the umbonal region. The right 

valve has a small anterior Pferm-like ear and well-preserved shells show a small anterior ear on the left valve. 

The main flank of the right valve is ornamented with 

relatively coarse, subdued, round-crested, radiating ribs, 

coarsest centrally, becoming weaker in both directions, 

passing into a noncostate area on the posterodorsal slope 

and into a weakly costate anterodorsal slope; the right 

valve has fairly regular, subdued concentric ribbing 

that produces a cancellated appearance. The left valve 

bears very weak, much subdued radiating ribs on its 

main flank, and these ribs become weaker and fade out 

on the dorsal slopes; narrow subdued concentric lining 

marks this valve.

Approximate dimensions of the right valve shown in 

plate 16, figure 4: Length 40 mm, height 37 mm, convexity 4 mm. The convexity of a left valve of comparable length may be as much as 14 mm.

The ligamental area is long and narrow and bears 

from 3 to 6 shallow ligamental pits of irregular length 

and spacing and differing markedly in both length and 

spacing on different individuals.

Types.—The holotype should be in the collection of the Academy of Natural Sciences, Philadelphia, but it is not listed 

among the Cretaceous types now preserved in that institution; 

presumably it is lost. Two topotypes from Owl Creek, Miss., 

USGS 707, USNM 128104; 1 topotype from the same source, 

USGS 6464, USNM 128102. Three plesiotypes from southeastern 

Missouri, USGS 16451, USNM 128105; USGS 16452, USNM 

128106; USGS 19090, USNM 128103.

Range.—So far as at present known this species is restricted 

in its stratigraphic range to the Owl Creek and Prairie Bluff 

formations of northern Mississippi and to the Owl Creek formation of southeastern Missouri. Geographically the species must 

have ranged at least from Mississippi to the head of the Gulf 

Embayment in Missouri.

Superfamily OSTRACEA

Family OSTREIDAE

Genus OSTREA Linne, 1758

Ostrea tecticosta Gabb

Plate 16, figures 13, 14

1860. Ostrea tecticosta, Gabb, Acad. Nat. Sci. Phila. Jour., 2d 

ser., v. 4, p. 403, pi. 68, figs. 47, 48. (For synonymy 

through 1941, see Tex. Univ. Pub. 4104, 1941, p. 107.)

The species Ostrea tecticosta Gabb is represented in 

the Owl Creek formation of southeastern Missouri 

(USGS 19090) by several rather poorly preserved internal molds on which the surface sculpture is weakly 

impressed. It is a small, simple oyster, the left valve 

of which is costate and the right valve noncostate. The 

species has been well described in several treatises (see 

synonymy) and its description will not be repeated in 

detail here.

Types.—Holotype, Academy of Natural Sciences of Philadelphia. Plesiotypes from southeastern Missouri, USGS 19090, 

USNM 128107.

Range.—The species ranges throughout the Atlantic and Gulf 

Coastal Plain, stratigraphically from the Exogyra ponderosa 

zone, where it is rather rare, upward through the E. costata 

zone, where it is common. This species is common in the Owl 

Creek and Prairie Bluff formations of Mississippi.

Genus EXOGYRA Say, 1820

Exogyra costata Say

Plate 16, figure 18

1820. Exogyra costata Say, Am. Jour. Sci., 1st ser., v. 2, p. 43.

(For synonymy through 1941, see Tex. Univ. Pub. 4101,

1941, p. 122.) 

Add: 

1940. Exogyra costata Say. Stephenson and Monroe, Miss. State

Geol. Survey Bull. 40, p. 274, pi. 7; p. 282, pi. 11, fig. 1.

(Illustrations only.)

Exogyra costata Say in the Owl Creek formation of 

southeastern Missouri is indicated by the imprints of 

two juvenile individuals, one represented by an internal 

and an external mold and the other by an internal 

mold (USGS 16452). Both reveal the characteristic 

costae of the species. Well-preserved shells are common in the Owl Creek formation of Mississippi 

(Stephenson and Monroe, 1940, p. 282, pi. 11, fig. 1). 

The species has been adequately described in the papers 

listed in the synonymy cited above.

Types.—The whereabouts of Say's original type material is 

unknown. The first illustrations of the species were those of 

Morton (1829, p. 85, pi. 6, figs. 1-4). Morton's material is not 

listed as preserved in the Academy of Natural Sciences, Philadelphia, and is presumably lost. Shells that have been generally accepted as belonging to this species have been described
112 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

and illustrated in many papers. One plesiotype from southeastern Missouri, USGS 16452, USNM 128108.

Range.—Exogyra oostata Say is a major zone marker in the 

Atlantic and Gulf Coastal Plain, ranging through beds considered to be approximately synchronous with the Maestrichtian of Europe, but possibly including the upper part of the 

Campanian.

Superfamily TBJGONIACEA

Family TBIGONIIDAE

Genus TRIGONIA Bruguiere, 1789

Trigonia angulicostata Gabb

Plate 16, figures 1-3

1876. Trigonia, angulicostata Gabb, Acad. Nat. Sci. Phila. Proc. 

for 1876, p. 312.

1926. Trigonia- angulicostata- Gabb. Stephenson, Ala. Geol. 

Survey Spec. Rep. no. 14, p. 248, pi. 91, fig. 2. (Illustration only.)

1940. Trigonia- anguliscostata Gabb. Stephenson and Monroe, 

Miss. State Geol. Survey Bull. 40, p. 280, pi. 10, fig. 10. 

(Illustration only.)

Imprints of Trigonia angulicostata Gabb, both external and internal molds, are common in the Owl Creek 

formation of southeastern Missouri. Most of them are 

incompletely preserved, but the characteristic angulation of the radiating ribs appear on some imprints 

(USGS 16429, 16430, 16451). Well-preserved shells 

showing the angulation of the ribs are present in the 

Owl Creek formation of Mississippi.

Shell small, moderately compressed, most inflated 

anteriorly, thinning wedgelike posteriorly, markedly 

inequilateral, equivalve; posterodorsal area flattish and 

separated into two narrow, parallel bands; the inner 

band is slightly excavated and borders the margin; the 

outer band forms a narrow, flattened, curved strip 

that slopes obliquely outward; a low obtusely angular 

ridge separates the two flattened bands, and a similar 

ridge separates the outer flattened band from the main 

lateral surface. Beaks nonprominent, incurved, opisthogyrate, situated about 0.2 the length from the anterior end. The main surface is ornamented with narrow, nodose ribs, separated by much wider, concave interspaces. These ribs, though roughly concentric with 

respect to the beak, are developed independently of the 

true concentric growth lines, which cross them obliquely. 

In the umbonal region the ribs extend from the outer 

angulation of the posterodorsal area in a broad curve 

down to the anterior margin; typically obliquely downward and rearward away from the beak a subobtuse 

angulation in the trend of the ribs appears and farther 

from the beak the successive ribs become more sharply 

angulated, attaining first a right angle, and eventually 

an acute angle toward the margin of the shell (pi. 16, 

fig. 1) ; beyond the last angulation the posterior ribs 

are shorter, weaker, and have only a slight curvature as 

they pass from the outer angulation above to the margin

below. The degree of angulation in the trend of the 

lateral ribs differs markedly on different individuals, 

and on an occasional shell the ribs pass in a regular 

curve to the lower margin without the angulation.

At the outer edge of the outer posterodorsal band each 

of the lateral ribs turns and extends as a weakly noded 

ridge obliquely forward across the band to the central 

ridge of the posterodorsal slope, thence turns and 

crosses the inner band transversely to the dorsal shell 

margin. The hinge and inner features of the shell are 

typical of the Trigonia scabra group of France (Upper 

Cretaceous), and need not be described here. (See 

Stephenson, 1941, p. 126.)

Dimensions of the shell shown in plate 16, figure 1: 

Length 25 mm, height 19 mm, convexity 6 mm.

Types.—Holotype (never figured), from Eufaula, Ala., Academy of Natural Sciences, Philadelphia. Two plesiotypes from 

Owl Creek formation, southeastern Missouri, USGS 16429, 

USNM 128109; plesiotype from Owl Creek, Miss., USGS 707, 

USNM 128110.

Range.—The species is known only from the Owl Creek formation and beds of Owl Creek age in the eastern Gulf region 

as far east as the Chattahoochee River, Georgia-Alabama.

Trigonia eufaulensis Gabb

Plate 16, figures 15-17 

1860. Trigonia eufalensis Gabb, Acad. Nat. Sci. Phila. Jour., 2d

ser., v. 4, p. 396, pi. 68, fig. 32.

1885. Trigonia eufaulensis Gabb. Whitfield, U. S. Geol. Survey

Mon. 9, p. 113, pi. 14, figs. 1, 2, 4 (not fig. 3). (Also

issued as N. J. Geol. Survey, Paleontology ser., v. 1.)

1907. Trigonia eufaulensis Gabb. Weller, N. J. Geol. Survey,

Paleontology ser., v. 4, p. 462, pi. 48, figs. 5-10. 

71916. Trigonia eufalensis Gabb. Gardner, Md. Geol. Survey, 

Upper Cretaceous [Maryland], in W. B. Clark and 

others, p. 582, pi. 34, figs. 1, 2. 

1923. Trigonia eufaulensis Gabb. Stephenson, N. C. Geol. and

Econ. Survey, v. 5, p. 189, pi. 54, figs. 1-4, (?5, 6). 

71926. Trigonia eufalensis Gabb. Wade, U. S. Geol. Survey Prof. 

Paper 137, p. 61, pi. 20, figs. 3, 4.

Among the imprints of Trigonia from the Owl Creek 

localities in southeastern Missouri (USGS 16430?, 

16452, 19090) are several incomplete internal and external molds that differ in detail of sculpture from 

Trigonia angulicostata Gabb, and appear to be referable to T. eufaulensis Gabb. The ribs are fewer and 

more widely spaced than in T. angulicostata, and they 

lack the characteristic angulation in the trend of the 

larger ribs of that species. T. eufaulensis appears to 

be less common in the Owl Creek formation than T. 

angulicostata.

Types.—Holotype, Academy of Natural Sciences, Philadelphia, from Eufaula, Ala. One topotype from Eufaula, Ala., 

USGS 854, USNM 128112; 2 plesiotypes from the Owl Creek 

formation of southeastern Missouri, USGS 19090, USNM 

128111.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 113

Range.—As identified and recorded this species ranges 

through the zones of Exogyra ponderosa and E. costata (Campanian through Maestrichtian) in the Atlantic and Gulf 

Coastal Plain.

Superfamily PECTINACEA

Family PECTINIDAE 

Genus PECTEN Mueller, 1776

Subgenus CAMPTONECTES (Agassiz US) Meek, 1864

Pecten (Camptonectes) bubonis Stephenson

Plate 17, figures 1-4

71916. Pecten argittensis Conrad. Gardner, Md. Geol. Survey, 

Upper Cretaceous [Maryland], in W. B. Clark and 

others, p. 588, pi. 34, figs. 3-5.

1941. Pecten (Camptonectes) bubonis Stephenson, Tex. Univ. 

Pub. 4101, p. 131, pi. 21, figs. 3-6.

Fragmentary imprints from the Owl Creek formation at three localities in southeastern Missouri (USGS 

16429, 16451, 19090) are referred to Pecten (Camptonectes) TyuJbonis Stephenson. The characteristic flat, 

curved, radiating costae of the species are clearly portrayed on the external molds and are less clearly impressed on the internal molds. A detailed description 

of the species is given in Texas University Publication 

4101 cited above.

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USGS 707, USNM 76432; one paratype from the same locality, 

USNM 76433. Two plesiotypes from southeastern Missouri, 

USGS 19090, USNM 128114. Two Plesiotypes from the Owl 

Creek formation, Mississippi, USGS 707, USNM 128113.

Range.—In the eastern* Gulf region the species is recorded 

from the Owl Creek formation of southeastern Missouri and 

northern Mississippi, and from the marine facies of the Providence sand (Owl Creek age) of Alabama and Georgia. In 

Texas the species in recorded from the upper part of the 

Navarro group in the Corsicana marl, the Kemp clay, and questionably in the Escondido formation. The species described by 

Gardner (1916, p. 588) as Pecten argillensis Conrad is questionably referable to this species.

As at present known the species is restricted to beds of 

late Maestrichtian age. However, closely related species occur 

in earlier Upper Cretaceous formations in the Coastal Plain.

Pecten (Camptonectes) hilgardi Stephenson? 

Plate 17, figure 5

1923. Pecten hilgardi Stephenson, N. C. Geol. and Econ. Survey, 

v. 5, p. 206, pi. 57, figs. 6, 7.

This species is questionably present in the collection 

from one locality in the Owl Creek formation of southeastern Missouri (USGS 16430). The material includes the external and internal molds of one individual 

and fragments of two external molds, all representing 

young stages of growth.

In form and radial ornamentation the species resembles that of Pecten (Camptonectes) bubonis Stephenson. The concentric scultpure is, however, much 

coarser; it consists of relatively prominent lamellae

spaced in this young stage 1 millimeter or less apart; 

these lamellae curl downward touching the surface below, thus forming hollow round-crested ridges. In the 

holotype from Mississippi, a much larger shell, the 

spacing of the concentric lamellae reaches a maximum 

of 3 millimeters near the outer margin. A detailed description of the species is given by Stephenson (1923, 

p. 206).

Types.—Holotype, from the lower part of the Ripley formation, Pontotoc County, Miss., USGS 6471, USNM 31669. Figured 

specimen from the Owl Creek formation, southeastern Missouri, 

USGS 16430, USNM 128115.

Range.—The species range appears to be through the Exogyra 

costata zone in the Atlantic and Gulf Coastal Plain. It has 

been recorded from the Ripley formation of Mississippi and the 

Peedee formation of North Carolina, and is here recorded from 

the Owl Creek1 formation of southeastern Missouri.

Subgenus SYN CYCLONE MA Meek, 1864

Pecten (Syncyclonema?) .simplicius Conrad

Plate 17, figure 6

1860. Pecten simplicius Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 4, p. 283, pi. 46, fig. 44. (For synonymy 

through 1941 see Tex. Univ. Pub. 4101, 1941, p. 133.)

Pecten simplicius Conrad, a small, simple smooth 

species, has been adequately described in several papers. 

Its presence in the Owl Creek formation in Missouri 

(USGS 16430, 18452, 19090) is indicated by several 

internal molds and one external mold. Beautifully 

preserved shells of the species are numerous in the Owl 

Creek formation at Owl Creek, Tippah County, Miss.

Types.—The type material is not listed as preserved in 

the collection of the Academy of Natural Sciences of Philadelphia and is probably lost. Euf aula, Ala., and Tippah County, 

Miss., are given as the known localities at the time of the 

original description. Plesiotype from southeastern Missouri 

USGS 16452, USNM 128116.

Range.—As recorded the species ranges through the zones 

of Exogyra ponderosa and E. costata in the Atlantic and Gulf 

Coastal Plain (Campanian through the Maestrichtian), and 

is abundant in some beds.

Family LIMIDAE

Genus LIMA Bruguiere, 1797

Lima acutilineata (Conrad)

Plate 17, figures 19-21

1858. Ctenoides acutilineata Conrad, Acad. Nat. Sci. Phila.

Jour., 2d ser., v. 3, p. 329, pi. 34, fig. 2. 

1923. Lima acutilineata (Conrad). Stephenson, N. C. Geol. and

Econ. Survey, v. 5, p. 215, pi. 58, figs. 4-9. 

1928. Lima acutilineata (Conrad). Adkins, Tex. Univ. Bull.

2838, p. 133.

Imprints of the shells of Lima acutilineata (Conrad) 

are fairly common in the Owl Creek formation in southeastern Missouri (USGS 16429 +16452,19090). Wellpreserved shells are present in the Owl Creek formation 

at the type locality in Tippah County. A description
114 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

and good illustrations of shells from Owl Creek are 

given by Stephenson (1923, p. 215, pi. 58, figs. 4-7). 

The shell is elongated obliquely rearward and downward and is only moderately inflated. The ventral and 

posterodorsal margins are approximately parallel. 

Sharp, narrow finely tuberculated costae are present 

over all the surface except the posterodorsal slope. The 

wider flattish interspaces bear numerous fine radiating 

lines. For further details see the reference cited above.

Dimensions of right valve shown in plate 17, figure 

19: Length 21 mm, height 18 mm, convexity about 

5 mm.

A varietal form of the species, Lima acutilineata 

teosana Stephenson (1941, p. 145, pi. 23, figs. 1, 2) is 

recorded from the Corsicana marl (Maestrichtian) of 

Texas.

Types.—The holotype, which came from the Owl Creek formation on Owl Creek, Tippah, County, Miss., is apparently lost. 

Four plesiotypes (=topotypes) from Owl Creek were figured 

by Stephenson (1923, pi. 58, figs. 4-7) and one of them (fig. 5) 

is refigured here on plate 17, figure 19, USGS 707, USNM 128117. 

Three plesiotypes from southeastern Missouri, USGS 16451, 

USNM 128118; USGS 16452, USNM 128119.

Range.—Upper part of Exogyra costata zone (Maestrichtian) 

in the Atlantic and Gulf Coastal Plain.

Superfamily MYTILACEA

Family MYTILIDAE

Genus CRENELLA Brown, 1827

Crenella serica Conrad

Plate 17, figures 11, 32

1860. Crenella (Stalagmium) serica Conrad, Acad. Nat. Sci. 

Phila. Jour., 2d ser., v. 4, p. 281, pi. 46, fig. 23. (For 

synonymy through 1941 see Tex. Univ. Pub. 4101, 1941, 

p. 153.)

This small bivalve mollusk is represented in the Owl 

Creek formation of southeastern Missouri at one locality (USGS 16429) by one internal and one external 

mold, both incomplete and too poorly preserved for 

illustration. Descriptions and illustrations are given 

by Stephenson (1923, p. 241, pi. 62, figs. 1, 2; 1941, 

p. 153, pi. 25, figs. 13-15). The adult shell is less than 

5 mm long and under 6 mm high. It is equivalve, 

plumply inflated and is delicately reticulated with fine 

radiating ribs crossed by evenly spaced fine concentric 

ridges. The hinge is edentulous. Although the type is 

not available the species is distinctive in form and ornamentation and no one has questioned the correctness of 

its identification as heretofore recorded.

-The present whereabouts of the holotype, which was 

recorded by Conrad as in the "Tuomey collection," is not known 

and is assumed to be lost. It came from the Cretaceous at 

Eufaula, Ala. A topotype from Eufaula is figured, USGS 854, 

USNM 128120. Two examples from southeastern Missouri, 

USGS 16429, USNM 128121.

Range.—With one possible exception the species as recorded 

is restricted in stratigraphic range to the Exogyra, costata zone 

in the Atlantic and Gulf Coastal Plain. Weller (1907, p. 510, 

pi. 56, figs. 7, 8) records it in the Marshalltown formation 

(upper part of E. ponderosa zone) in New Jersey, but his 

illustrations do not show the surface ornamentation in sufficient detail to permit critical comparison with authentic examples of the species.

Crenella microstriata Stephenson, n. sp. 

Plate 17, figures 7-10

?1916. Crenella elegantula Meek and Hayden. Gardner, Md. 

Geol. Survey, Upper Cretaceous [Maryland], in W. B. 

Clark and others, p. 625, pi. 38, fig. 19.

Internal molds of Crenella microstriata, n. sp., with 

radiating sculpture obscurely impressed upon them are 

present in the Owl Creek formation at two localities in 

Stoddard County (USGS 16451, 16452) and at one locality in Scott County (USGS 16597). Well-preserved 

shells occur in the Owl Creek formation at Owl Creek, 

Tippah County, Miss., one of which is selected as holotype of the species.

Shell large for the genus, thin, inflated, subovate in 

outline, higher than longj slightly inequilateral, equivalve, with steep dorsal slopes. Lunule and escutcheon 

wanting. Beaks prominent, incurved, prosogyrate, approximate, nearly central. Dorsal margin arched, anterior margin broadly rounded, ventral margin sharply 

rounded, posterior margin broadly rounded, becoming 

subtruncated in adults. Surface ornamented evenly 

all over with very fine radiating ribs numbering 6 to 8 

to the millimeter near the ventral margin of adults; 

these are crossed by very fine concentric lines, thus producing a delicately reticulated surface. Hinge very 

thin, edentulous. A narrow slit extends from the tip 

of the beak rearward and obliquely inward to the inner 

dorsal margin. Inner margin finely crenulated, the 

crenulations corresponding to the ends of the ribs and 

interspaces.

Dimensions of the holotype: Length 10 mm, height 

12.7 mm, convexity about 4 mm. A large paratype from 

Owl Creek, Miss., measures: Length 13 mm, height 16.3 

mm, convexity 7 mm.

In size and form Crenella microstriata is very similar to C. elegantula Meek and Hayden from the Fox 

Hills sandstone, Wyoming, but the ribbing of the latter 

is consistently coarser, having only 5 or 6 ribs to the millimeter near the ventral margin. The specimen from 

the Monmouth formation (Upper Cretaceous) of Maryland, referred by Gardner (1916, p. 625, pi. 36, fig. 19) 

to C. eleffantula, possesses finely radiating striae similar 

to, but apparently a little coarser than, those on the shell 

of C. microstriata. Specimens from the Tinton sand 

member of the Eed Bank sand (Upper Cretaceous) of 

New Jersey, referred by Weller (1907, p. 511, pi. 56,
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 115

fig. 6) to G. elegantula, are similar in size and form to 

C. microstriata, but the illustration accompanying his 

description fails to show the pattern of the striae.

Type,—Holotype, from the Owl Creek formation, Owl Creek, 

Tippah County, Miss., USGS 707, USNM 128123; 2 unflgured 

paratypes from the same source, USGS 75, USNM 20617; 1 figured paratype from southeastern Missouri, USGS 16451, USNM 

128126; 6 unfigured paratypes from Missouri, USGS 16452, 

USNM 128124; 1 unfigured paratype from Missouri, USGS 

16597, USNM 128125.

Range.—Owl Creek formation (Maestrichtian) in Mississippi 

and Missouri.

Cuneolus tippanus (Conrad) 

Plate 17, figures 13, 14

1858. Dreissena tippana Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 328, pi. 34, fig. 14.

(For synonymy and description see Tex. Univ. Pub. 

4101, 1941, p. 157, pi. 25, figs. 20-26.)

The incomplete internal and external molds of one 

individual are present in one collection from the Owl 

Creek formation of southeastern Missouri (USGS 

19090). The description cited is based on well-preserved shells from the type locality on Owl Creek, 

Tippah County, Miss. The original type material is 

not listed as present in the collection of the Academy 

of Natural Sciences, Philadelphia, and is believed to 

be lost. The shell is of moderate size, inflated, falcate, 

mytiliform, smooth. It is a simple, easily recognized 

shell and the material available for comparison does 

not seem to afford a basis for the recognition of more 

than one species of the genus.

Types.—Whereabouts of holotype unknown, probably lost. 

Neotype (designated by Stephenson, 1941, p. 158) from Owl 

Creek, Tippah County, Miss., USGS 6464, USNM 76499. Mentioned example from Owl Creek formation of southeastern 

Missouri, USGS 19090, USNM 128127.

Range.—The recorded range of the species is through the 

zone of Exogyra, costata (Maestrichtian) in the Atlantic and 

Gulf Coastal Plain.

Order ANOMALODESMACEA 

Superfamily PANDORACEA

The superfamily name Pandoracea was proposed by 

Stewart (1930, p. 26, footnote), who finds that the 

name Anatina Schumacher as a generic name for the 

group, typified by Solen anatinus Linne, is invalid. 

He considers Pandora Bruguiere an appropriate genus 

to typify the superfamily.

Family PHOLADOMYACIDAE

Genus PHOIADOMYA Sowerby, 1823

Pholadomya tippana Conrad

Plate 18, figures 8-13

1858. Pholadomya tippana Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 324, pi. 34, fig. 9. 

1860. Pholadomya occidentalis Morton. Conrad, Acad. Nat. Sci.

Phila. Jour., 2d ser., v. 4, p. 276.

1860. Pholadomya Occidentalis Morton. Owen, Geol. Recon.

Ark. 2d Kept, pi. 8, fig. 9. (No text.) 

1916. Pholadomya conradi Gardner, Md. Geol. Survey, Upper

Cretaceous [Maryland], in W. B. Clark and others,

p. 632, pi. 38, fig. 1. 

1940. Pholadomya tippana Conrad. Stephenson and Monroe,

Miss. State Geol. Survey Bull. 40, p. 282, pi. 11, figs.

2, 3. (Illustrations only.)

The specimen of Pholadomya tippana from the Owl 

Creek formation at Owl Creek, Tippah County, Miss., 

originally figured by Conrad (1858, p. 324, pi. 34, fig. 9) 

was small and incomplete. It is not listed in the collection of the Academy of Natural Sciences and is presumed to be lost. A dozen or more specimens, most of 

them larger and more completely preserved, are in a 

collection from the Owl Creek locality, made by T. W. 

Stanton in 1889. Conrad's original figure, though 

poor, is adequate for the satisfactory identification of 

the specimens subsequently obtained from the type 

locality. Gardner in her description of Pholadomya 

conradi cited Tippah County, Miss., as the type locality, but her one illustrated specimen was obtained from 

a locality in the marine f acies of the Providence sand 

(upper Maestrichtian), 1.5 miles north of Fort Deposit, 

Lowndes County, Ala.; this figured specimen appears 

to be identical with Conrad's species.

One fragmentary young shell referred by Wade 

(1926, p. 73, pi. 24, fig. 1) to Pholadomya conradi Gardner appears to have nonprominent beaks, and is probably not that species.

The available topotypes consist of internal molds 

with the radial sculpture sharply impressed upon them, 

and irregular patches of the thin shell adhere over 

parts of their surfaces. Shell large, very thin, elongate, inflated anteriorly, thinning wedgelike posteriorly, gaping widely at the rear, markedly inequilateral, 

equivalve. Beaks very prominent, incurved, nearly 

direct, approximate, situated about 0.18 the length 

of the shell from the anterior extremity. Anterior margin rounding regularly from the beaks to the very 

broadly rounded ventral margin, posterior margin 

rounded narrower than a semicircle, dorsal margin 

back of the beaks straight. Lunule and escutcheon 

wanting. Surface ornamental with numerous (25 to 

28) narrow more or less irregularly spaced radiating 

costae, the widest spacing being on the posterodorsal 

and anterior slopes; regular weak noding is present on 

the ribs in the umbonal region; toward the margins 

the nodes become irregular in strength, producing a 

roughened crest on each rib. Hinge and internal features not uncovered.

Dimensions of the medium-sized topotype shown in 

plate 18, figure 8: Length 79 mm, height 64 mm, thick-, 

ness about 43 mm. Dimensions of the internal mold
116 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

from southeastern Missouri shown in plate 18, figure 

13: Length about 91 mm, height about 72 mm, thickness 51 mm.

Types.—Whereabouts of holotype unknown. Two topotypes 

figured, USGS 707, USNM 128128; 11 unfigured topotypes, USGS 

707, USNM 20716. One plesiotype from Stoddard County, 

Mo., USGS 16454, USNM 128129 ; 1 plesiotype from Scott County, 

Mo., USGS 16453, USNM 128130.

Range.—Available data indicate that the range of this species 

is restricted to the Owl Creek formation, the Providence sand, 

and to corresponding beds desposited late in Cretaceous time. 

However, closely related species occur in the Blpley formation 

beneath the Owl Creek formation, and in corresponding beds of 

Blpley age.

Family IATERNUIIDAE

Genns AMATIMYA Conrad, 1860

Anatimya anteradiata (Conrad)

Plate 17, figures 15-17

1860. Pholadomya (Anatimya) anteradiata Conrad, Acad. Nat. 

Sci. Phila. Jour., 2d ser., v. 4, p. 276, pi. 46, fig. 3.

The presence of Anatimya anteradiata (Conrad) in 

the Owl Creek formation of southeastern Missouri is 

indicated by one fragmentary imprint from Stoddard 

County (USGS 19090). The description is based 

mainly on six topotypes from Owl Creek, Miss.

Shell thin, of medium size, compressed, subelliptical 

in outline, subequilateral, equivalve. Umbonal ridge 

low, weak, posterodorsal slope broadly excavated. 

Beaks small, nonprominent, fissured, nearly direct, approximate, situated about at the midlength. Anterodorsal margin nearly straight, nearly horizontal, anterior margin evenly rounded, ventral margin nearly 

straight to very broadly rounded, posterior margin subtruncated, posterodorsal margin nearly straight and 

nearly horizontal.

The surface presents fine growth lines and coarser 

growth undulations. A group of 8 to 10 sharp, irregularly spaced radiating ribs diverge fanlike 

obliquely downward and rearward, spreading a few 

millimeters on either side of the umbonal ridge. The 

posterodorsal slope is nearly smooth, but some individuals exhibit 1 or 2 faint radiating ribs. Hinge edentulous, external ligamental groove opisthodetic, short, 

shallow. One of the topotypes shows a pair of opposing 

short, stout, spoon-shaped chondrophores, protruding 

inward and directly downward from under the beaks. 

The adductor scars, pallial line, and pallial sinus cannot 

be seen on the available material, but as seen on a related species, Anatimya languid Stephenson, in the 

Woodbine formation of Texas (Stephenson, 1953, p. 90, 

pi. 21, fig. 2), the pallial sinus is wide, deep, and rounded 

on the front, but falls short of reaching the midlength 

of the shell.

The fragment of the imprint from the Owl Creek 

formation of Missouri (pi. 17, fig. 17) pertains to the 

posterior part of a right valve and includes impressions 

of five of the group of sharp radiating ribs.

Types.—Holotype, collection of the Academy of Natural 

Sciences of Philadelphia; this type came from "Tippah County, 

Miss.," and because it was collected by Dr. W. Spillman it is 

assumed that it was collected at the Owl Creek locality. Two 

topotypes, figured, USGS 707, USNM 128132; 1 plesiotype from 

the Owl Creek formation of southeastern Missouri, USGS 19090, 

USNM 128131.

Range.—As at present known the species is restricted to the 

Owl Creek formation of Mississippi and southeastern Missouri. 

A closely related variety, Anatimya anteradiata texana Stephenson, is recorded from the Nacatoch sand (Navarro group) of 

Texas (Stephenson, 1941, p. 161, pi. 25, fig. 11).

Anatimya? sp. 

Plate 17, figure 18

The external molds of the dorsal parts of both valves 

of one individual, questionably referred to Anatimya 

Conrad, is present in the collection from one locality in 

the Owl Creek formation of southeastern Missouri 

(USGS 16451). These molds appear to pertain to a 

medium-size elongate shell, moderately inflated in the 

umbonal region, with the beaks nonprominent and nearly direct; from the beak forward the surface is ornamented with relatively coarse concentric ridges and toward the rear the surface appears to become smooth. 

In form the shell resembles the genus Anatimya but no 

evidence of a slit in the beak could be detected. USNM 

128133.

Superfamily POROMYACEA

Family POROMYACIDAE

Genus LIOPISTHA Meek, 1864

Liopistha protexta (Conrad)

Plate 19, figures 17-21

1853. Cardium protextum Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 2, p. 275, pi. 24, fig. 12.

(For synonymy through 1941 see Tex. Univ. Pub. 4101, 

1941, p. 162.)

Imprints of the shells of Liopistha protexta (Conrad) are present in the collections from every locality at 

which Owl Creek fossils were obtained in southeastern 

Missouri. Specimens with more or less of the shell preserved are abundant at the Owl Creek locality in Tippah County, Miss.

The species has been fully delineated in several treatises (see synonymy) and need not be described in 

detail here. It may be noted, however, that there is 

some individual variation in the number and coarseness 

of the radial ribs. Although the species has been recorded in beds older than the Owl Creek formation at a 

few scattered localities in the Atlantic and Gulf Coastal 

Plain it is nowhere as abundant as it is in the Owl
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 117

Creek formation. The imprints from Missouri include 

both internal and external molds, none of which show 

impressions of complete individuals. The shells of this 

species are very thin, which accounts for the fact that 

the radiating ribs are impressed on all the internal 

molds. Impressions of the characteristic fine nodes on 

the ribs may be seen on some of the external molds. 

The right valve from Owl Creek, Miss., shown in plate 

19, figure 18, measures: Length 30 mm, height 19 mm, 

convexity about 8 mm.

Types.—Holotype, from Burlington County, N. J., Academy 

of Natural Sciences, Philadelphia. Two plesiotypes from Owl 

Creek, Tippah County, Miss., USGS 707, USNM 128136; 

1 plesiotype from the Owl Creek formation, Stoddard Co., Mo., 

USGS 16451, USNM 128134; USGS 16452, USNM 128135.

Range.—Exogyra costata zone in the Atlantic and Gulf 

Coastal Plain; abundant in the Owl Creek formation in Mississippi and southeastern Missouri and elsewhere in beds of Owl 

Creek age (upper part of zone) ; less abundant in the Ripley 

formation and beds of Ripley age (lower part of zone). Reported in the Wenonah sand (upper part of E. ponderosa zone), 

New Jersey.

Order TELEODESMACEA 

Superfamily CYPRICARDIACEA

Family PLETJROPHORIDAE

Genus VENIELLA Stoliczka, 1870

Veniella conradi (Morton)

Plate 18, figures 1, 2

1833. Venilia conradi Morton, Am. Jour. Sci., 1st ser., v. 23, 

p. 294, pi. 8, figs. 1-2.

(For synonymy through 1941 see Tex. Univ. Pub. 4101, 

1941, p. 168.)

Veniella conradi (Morton) is represented by poorly 

preserved internal and external molds at four localities 

in southeastern Missouri (USGS 16451, 16452, 16597, 

and 19090). Detailed descriptions of the species and 

full accounts of its distribution in the Atlantic and Gulf 

Coastal Plain are given in several treatises (see synonymy).

Types.—Holotype, collection of the Academy of Natural 

Sciences, Philadelphia, from "New Jersey," probably from the 

Navesink marl. The specimen in the Academy marked "type" 

is badly broken. One plesiotype from Owl Creek, Tippah 

County, Miss., USGS 707, USNM 128138. One plesiotype from 

the Owl Creek formation, southeastern Missouri, USGS 19090, 

USNM 128137.

Range.—The species ranges through the zones of Exogyra 

ponderosa and E. costata in the Atlantic and Gulf Coastal Plain.

Superfamily ASTARTACEA

Family CRASSATELLIDAE

Genus CRASSATELLA Lamarck, 1799

Crassatella vadosa ripleyana (Conrad)

Plate 19, figures 11-16

1858. Crassatella ripleyana Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 327, pi. 35, fig. 3.

1905. Crassatellites ripleyanus (Conrad). Johnson, Acad. Nat. 

Sci. Phila. Proc., v. 57, p. 14.

1941. Crassatella vadosa ripleyana (Conrad). Stephenson, Tex. 

Univ. Pub. 4101, p. 177.

1945. Crassatella vadosa Morton. Harbison, Acad. Nat. Sci. 

Phila. Proc., v. 97, p. 80, pi. 1, fig. 2 (from the Owl Creek 

formation, Owl Creek, Tippah County; not from the 

Ripley formation at Pleasant Ridge Lake).

Crassatella vadosa ripleyana (Conrad) belongs to a 

group of closely related Crassatellas, typified by C. 

vadosa Morton (1834, p. 66, pi. 13, fig. 12). This group 

includes Crassatellites vadosus (Morton) Wade, equals 

Crassatella vadosa wadei (Stephenson, 1941, p. 176, 

177), from the Coon Creek tongue of the Bipley formation, McNairy County, Tenn. (Wade, 1926, p. 79, pi. 25, 

figs. 6-8); Crassatella gardnerae Harbison (1945, p. 79, 

pi. 1, figs. 3, 4) from the Ripley formation of Mississippi; Crassatellites vadosus (Morton) Gardner, from 

theMonmouth formation of Maryland (Gardner, 1916, 

p. 649, pi. 39, figs. 1-4); three varietal forms from the 

Navarro group of Texas, Crassatella vadosa chatfieldensis Stephenson from the Nacatoch sand, C. vadosa 

manorensis Stephenson, and C. vadosa bexarensis 

Stephenson (1941, pp. 177-178, pi. 29, figs. 1-11) from 

the Kemp clay.

Imprints of Crassatella vadosa ripleyana (Conrad), 

both internal and external molds of juvenile shells, 

mostly fragmentary, are common in the Owl Creek 

formation of southeastern Missouri (USGS 16429 + 

16452, 16430,16598,19090). The following description 

is based on perfectly preserved topotypes from Owl 

Creek, Miss.

Shell of medium size, subtrigonal in outline, rather 

strongly inflated in the umbonal region, inequilateral, 

subequivalve; anterodorsal slope steep; posterodorsal 

slope elongated, rather broad, sinuous, somewhat flattened, separated from the main flank by a broad subobtusely angular umbonal ridge; this slope is divided 

into 3 bands by 2 weak radial ridges. Lunule relatively 

short, deeply excavated, the left half a little wider than 

the right half; escutcheon long, deeply and sharply 

excavated in the right half, and narrower and weakly 

excavated in the left half. A broad, weak radial depression in front of the umbonal ridge extends from the 

umbonal region to the ventral margin.

Anterior margin evenly rounded; ventral margin 

broadly rounded, nearly straight, or slightly and 

broadly excavated; posterior margin short, subtruncated; posterodorsal margin nearly straight, descending. Beaks prominent, incurved, prosogyrate, 

approximate, situated 0.34 the length from the anterior 

extremity. Surface of shell has rather coarse, irregular 

growth ridges and intervening fine growth lines. Corrosion reveals internal radiating shell structure.
118 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Dimensions of the topotype shown in plate 19, figures 

11, 12: Length 47 mm, height 37.5, thickness 28 mm.

Hinge plate thick, relatively short. Ligament (resilium) short internal, seated in a spoon-shaped depression (resilif er) in the hinge plate btlow and a little back 

of the beak. Left valve has a deep trigonal socket separating two cardinal teeth, the anterior one strong, 

the posterior one prominent, sharp, standing between 

the resilif er and the inner margin of the hinge. A ridge 

on the inner edge of the limule fits into a corresponding 

channel on the margin of the right valve, and a channel 

paralleling the inner margin of the escutcheon receives 

a marginal ridge of the right valve. A prominent 

trigonal cardinal tooth on the right valve fits into the 

deep socket of the left hinge; in front of the cardinal 

tooth is a socket to accommodate the anterior cardinal 

of the left valve, and a posterior socket, separating the 

resilifer from the inner margin of the hinge plate, receives the posterior cardinal of the left valve. The sides 

of the large trigonal cardinal tooth of the right valve 

and of the corresponding socket of the left valve are 

striated in the direction of hinge movement. The posterior adductor scar is subcircular and the anterior 

adductor is elliptical; both are sunken well below the 

inner surface. Pallial line simple. Inner margin 

crenulated.

Compared with the typical Crassatella vadosa Morton 

this variety is shorter, more ventricose, more prominent 

in the umbonal region, and narrows to a more pointed 

posterior extremity.

Types.—Holotype, collection of the Academy of Natural 

Sciences of Philadelphia. Three topotypes from Owl Creek, 

USGS 707, USNM 128139; 1 plesiotype from southeastern Missouri, TJSGS 16429, USNM 128141; 1 plesiotype from southeastern Missouri, USGS 19090, USNM 128140.

Range.—Owl Creek formation of Mississippi and southeastern 

Missouri.

Genus SCAMBULA Conrad, 1869

Scambula perplana Conrad

Plate 18, figures 3-5

1869. Scambula perplana Conrad, Am. Jour. Conchology, v. 5, 

p. 48, pi. 9, figs. 7, 8.

(For synonymy and description see Tex. Univ. Pub. 

4101, 1941, p. 182, 183, pi. 26, figs. 11, 12.)

The small compressed species, Scambula perplana 

Conrad, is represented in the Owl Creek formation of 

southeaster]! Missouri by several fairly well preserved 

internal molds and by one incomplete external mold 

(USGS 16452,19090). One specimen, an internal mold 

of a left valve, is recorded from the Owl Creek formation of Mississippi at a locality about 3 miles south of 

New Albany, Union County (USGS 6872). Fairly well 

preserved shells that appear to be correctly referred to

the species are recorded from the Coon Creek tongue 

of the Bipley formation (early Maestrichtian ?) at the 

classic Coon Creek locality in McNairy County, Tenn. 

(Wade, 1926, p. 82, pi. 25, figs. 11,12,15,16).

Types.—Holotype, collection of the Academy of Natural 

Sciences Philadelphia, from the Woodbury clay (Easogyra ponderosa zone) at Haddonfield, N. J. Three plesiotypes from the 

Owl Creek formation, southeastern Missouri, USGS 19090, 

USNM 128142.

Range.—Zones of Exogyra ponderosa and E. costata (Campanian through Maestrichtian) in the Atlantic and Gulf Coastal 

Plain.

Superfamily CARDIACEA

Family CARDIIDAE

Genus CARDIUM Linne, 1758

Subgenus GRANOCARDIUM Gabb, 1869

Cardium (Granocardium) tippanum Conrad

Plate 19, figures 9,10

1858. Cardium tippanum Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 326, pi. 34, fig. 8b. 

1864. Cardium (Acanthocardia) tippanum Conrad. Meek,

Check list of the invertebrate fossils of North America,

Cretaceous and Jurassic, Smithsonian Misc. Coll. 177,

p. 12. 

187G. Cardium (Granocardium) tippanum Conrad. Gabb, Acad.

Nat. Sci. Phila. Proc., v. 28, p. 310.

1940. Cardium (Granocardium) tippanum Conrad. Stephenson 

and Monroe, Miss. State Geol. Survey Bull. 40, p. 284, 

pi. 12, figs. 1, 2. (Illustrations only.)

1941. Cardium (Granocardium) tippanum Conrad. Stephenson, 

Tex. Univ. Pub. 4101, p. 199, pi. 37, figs. 9-12.

Meek (1864, p. 12) referred Cardium tippanum Conrad to the subgenus Acanthocardia Gray, a Recent 

group inhabiting the marine waters of the northeast 

Atlantic. Acanthocardia differs from Granocardiwn 

in having the spines on the crests of the ribs instead of 

in the interspaces.

Fragmentary imprints of both internal and external 

molds of Cardiu/m (Granocardium) tippanum Conrad 

are present in the collections from four localities in the 

Owl Creek formation in Stoddard County, Mo. (USGS 

16429 +16452,16430,16451,19090). A detailed description of the species is given by Stephenson (1941, p. 199, 

pi. 37, figs. 9-12) ; the well-preserved topotype from the 

Owl Creek formation of Mississippi, there figured, was 

designated neotype; it is refigured in this paper (pi. 19, 

fig. 9).

Types.—The whereabouts of the holotype is unknown. Neotype (designated by Stephenson, 1941, p. 200), from Owl Creek, 

Miss., USGS 707, USNM 76611; 1 plesiotype from southeastern 

Missouri, USGS 16451, USNM 128143.

Range.—As at present known the species is restricted to the 

Owl Creek formation and to beds of Owl Creek age in the eastern Gulf region, and to the Corsicana marl of Texas. It appears 

to be confined in range to the upper part of the Exoffyra costata 

zone (upper Maestrichtian).
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 119

Gardium (Granocardium) lowei Stephenson, n. sp. 

Plate 19, figures 1-8

Imprints of a species of Cardiwn, (Gfranocardium) 

Gabb that appear to be essentially like a heretofore undescribed species from Owl Creek, Tippah County, 

Miss., are present in collections from five localities in 

the Owl Creek formation of southeastern Missouri 

(USGS 16429 + 16452, 16430, 19090, Stoddard County; 

16597, 16598, in Scott County). The description is 

based mainly on nine Mississippi specimens, the original shells of which are more or less completely preserved.

Shell thin, strongly inflated, subquadrate in outline, 

subequilateral, equivalve. Beaks prominent, strongly 

incurved, slightly prosogyrate, approximate, situated 

centrally. Dorsal slopes steep, the posterior one flattened. Radiating ribs numerous, flattened on crests, 

closely spaced, some of them bearing a weak radiating 

groove midway of their 'flattened crests. As a rule 

every fourth interspace on the main flank is occupied 

by relatively large spines that may be regularly spaced, 

or may be widely and irregularly spaced; however, the 

large spines occupy every third interspace on parts of 

some shells. Most of the larger spines are broken away 

on the available material, but their presence is indicated 

by scars; on the dorsal slopes the number of interspaces 

between those bearing the rows of larger spines may 

range from 2 to 7. There is considerable individual 

variation in the number and spacing of the larger 

spines. The larger spines are solid and some of them, 

accidentally broken away during removal of the matrix, 

rose as much as 1 millimeter above the shell surface. 

Some of the interspaces that do not bear large spines 

reveal a very weak development of closely spaced tiny 

spines or tubercles, or the interspaces and parts of 

interspaces may appear smooth; however, on some 

small areas where an outer layer of shell has been removed the inner shell structure shows incipient, tiny, 

closely spaced tubercles that do not come to the outer 

surface. The termini of the radiating ribs and interspaces produce a fine crenulation on the inner margin 

of the shell.

The ligamental groove is opisthodetic, short and very 

narrow; in each valve it is bordered on the outside by a 

paralleling groove that is V-shaped in cross section, and 

on the inside by a narrow, moderately prominent 

nymph. The hinge is narrow, the inner dental elements overhanging the interior slightly. In the left 

valve a short bluntly pointed posterior cardinal tooth 

rises below and slightly back of the tip of the beak; in 

front of this tooth and extending around below it is a

deep, irregular cavity, the front part of which is a tooth 

socket; below the cavity and slightly toward the front 

is a short, prominent, upcurved anterior cardinal tooth. 

Above the socket the thin margin of the shell folds up 

against the front side of the incurved beak. The anterior lateral tooth is distant, short, and relatively thick 

and is separated from the thin margin by a short, deep 

socket; the posterior lateral tooth is also distant, short, 

and thick and is near the margin.

In the right valve a small pointed anterior cardinal 

tooth fits into the socket of the left valve and back of 

this tooth is a socket that receives the small posterior 

cardinal of the left valve; below this socket is a prominent, short, upturned posterior cardinal that fits against 

the posterior side of the anterior cardinal of the left 

valve. The tip of the prominent cardinal in each valvefits into a deeply submerged shallow dent (socket) low 

on the inner side of the opposite valve. The anterior 

lateral dentition of the right valve is a pair of claspers 

the inner element of which is thick and strong and the 

outer element small and weak; the posterior lateral 

dentition includes a strong inner element separated 

from the margin of the shell by a deep socket that accommodates the single lateral tooth of the left valve.

Inner surface smooth, adductor scars not indented; 

posterior adductor scar relatively large and somewhat 

elongated; anterior adductor smaller, subcircular.

Dimensions of the holotype, a specimen of medium 

size: Length 11.5 mm, height 12.6 mm, convexity 5 mm. 

The adult paratype from Owl Creek shown in plate 19, 

figure 1, measures: Length 17 mm, height 20 mm, convexity about 7 mm.

Gardium (Granocardium) lowei is closely related to 

0. (6r.) alabamense Gabb from Eufaula, Ala. (Gabb, 

1876, p. 310), a species in which the larger spines on the 

lateral surface occupy every third interspace, are more 

closely and more regularly spaced, and whose smaller 

spines in the intervening spaces are much more conspicuously developed. Gabb apparently failed to recognize the spine scars on the type specimen. (See 

Stephenson, 1923, p. 295, pi. 72, figs. 9,10, lOa.)

Types.—Holotype, a medium-size shell from Owl Creek, Tippah County, Miss., USGS 707, USNM 128148; 2 figured paratypes from the same source, USNM 128147; 5 unfigured paratypes from the same source, USNM 20854; 1 unfigured paratype 

from the same source, USGS 594, USNM 21675. Two figured 

paratypes from the Owl Creek formation southeastern Mi ssouri, 

USGS 19090, USNM 128144; 4 unfigured paratypes from the 

same source, USNM 128145; 1 figured paratype, USGS 16597, 

USNM 128146. Named in honor of the late Dr. E. N. Lowe, 

past Director of the Mississippi State Geological Survey.

Range.—Owl Creek formation of Mississippi and southeastern Missouri.
120 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Submenus PACHYCARDITTM Conrad, 1869

Cardium (Pachycardium) spillmani Conrad

Plate 20, figure 1

1858. Cardium (Laevicardium) spillmani Conrad, Acad. Nat.

Sci. Phila. Jour., 2d ser., v. 3, p. 326, pi. 34, fig. 3. (See

synonymy in N. C. Geol. and Econ. Survey, v. 5, pt. 1,

1923, p. 298.) 

Add: 

1876. Cardium (Pachycardium) spillmani Conrad. Gabb, Acad.

Nat. Sci. Phil. Proc., v. 28, p. 309.

Two small internal molds of about the same size, 

representing a juvenile stage of Cardium (Pachycardium) spillmani Conrad, were found at one locality in the 

Owl Creek formation of southeastern Missouri (USGS 

16452). The type locality of the species is Owl Creek, 

Tippah County, Miss. Twenty-eight topotypes in the 

collection of the United States National Museum 

(USNM 20615, 20857, and 21665) afford examples of 

growth stages of the species ranging in greatest dimension (in height) from 16 to 142 mm. A description 

of the species, including its distribution, is given by 

Stephenson (1923, p. 298).

The following species are closely related to Cardium 

(Pachycardium) spillmani: C. (P.) stantoni Wade 

(1926, p. 86) and C. (P.) wadei Stephenson (1941, 

p. 194).

Types.—Holotype, from Owl Creek, Tippah County, Miss., collection of the Academy of Natural Sciences of Philadelphia. 

Plesiotype (juvenile) from the Owl Creek formation of southeastern Missouri, USGS 16452, USNM 128149; 1 unfigured example from the same source, USNM 128150.

Range.—The stratigraphic range of this species has been 

given as through the zones of Essogyra ponderosa and E. costata ; 

but it is probable that internal molds of this subgenus belonging to closely related species, such as Cardium (Pachycardium) 

stantoni Wade (1926, p. 86), have been mistakenly referred to 

C. (P.) spillmani, and the true range may not be as great as 

previously recorded.

Genus BREVICARDIUM Stephenson, 1941

Brevicardium fragile Stephenson

Plate 18, figures 6, 7

1941. Brevicardium fragile Stephenson, Tex. Univ. Pub. 4101, 

p. 204, pi. 36, figs. 5-8.

The small species, Brevicardium fragile Stephenson, 

is represented in southeastern Missouri by one internal 

mold of a right valve on which the surface sculpture is 

obscurely impressed (USGS 16452). The mold agrees 

well with the holotype of the species, which came from 

Owl Creek, Tippah County, Miss.; the types are described in my treatise on the Navarre group of Texas 

(Stephenson, 1941, p. 204), where the species has been 

questionably identified in the Corsicana marl. A topotype, a right valve from Owl Creek, shown in plate 18,

figure 6, measures: Length 5.7 mm, height 5.7 mm, convexity about 2 mm. The internal mold from Missouri 

measures: Length 4.8 mm, height 4.7 mm, convexity 

about 1.5 mm.

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USGS 707, USNM 76644; 1 plesiotype (=topotype) from the 

same source, USGS 6164, USNM 128151. One plesiotype from 

southeastern Missouri, USGS 16452, USNM 128152.

Range.—Owl Creek formation of Mississippi and southeastern 

Missouri. Questionably in the Corsicana marl (Navarro group), 

Texas.

Superfamily VENERACEA

Family VENERIDAE

Genus APHRODINA Conrad, 1869

Aphrodina tippana (Conrad)

Plate 20, figures 2-4

1858. Meretrix tippana Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 326, pi. 34, fig. 18. (For synonymy see

Tex. Univ. Pub. 4101, 1941, p. 208.) 

Add: 

1940. Aphrodina tippana (Conrad). Stephenson and Monroe,

Miss. State Geol. Survey Bull. 40, p. 284, pi. 12, figs.

5, 6. (Illustrations only.)

A few small, poorly preserved, incomplete internal 

molds of Aphrodina tippana (Conrad) are present in 

the collections from three localities in Stoddard County, Mo. (USGS 16429 + 16452,16451,19090). The type 

locality of the species in Owl Creek, Tippah County, 

Miss., where well-preserved shell are of common occurrence. The species has been described in detail in 

the papers cited in the synonymy.

Types.—Holotype, Academy of Natural Sciences Philadelphia, from Owl Creek, Tippah County, Miss. On topotype 

USGS 707, USNM 128154; 2 plesiotypes from the Own Creek 

formation , of southeastern Missouri, USGS 19090, USNM 

128153.

Range.—Exogyra costata zone (Maestrichtian) in the Atlantic and Gulf Coastal Plain.

Genus CYPRIMERIA Conrad, 1864

Cyprimeria alta (Conrad)

Plate 20, figures 26-28

1858. Dosinia densata Conrad, Acad. Nat. Sci. Phila, Jour.

2d ser., v. 3, p. 325, pi. 34, fig. 13. 

1875. Cyprimeria alta Conrad, N. C. Geol. Survey, Kept., v. 1

(by W. C. Kerr), app. A, p. 27. 

7187Q. Cyprimeria torta Gabb, Acad. Nat. Sci. Phila. Proc.?

v. 28, p. 308. 

1916. Cyprimeria major Gardner, Md. Geol. Survey, Upper

Cretaceous [Maryland], in W. B. Clark and others,

p. 689, pi. 40, figs. 11, 12; pi. 41, figs. 1-4; pi. 42, fig. 1;

pi. 43, fig. 1.

1940. Cyprimeria alta (Conrad). Stephenson and Monroe, 

Miss. State Geol. Survey Bull. 40, p. 284, pi. 12, figs. 

3, 4. (Illustrations only.)

1941. Cyperimeria alta (Conrad). Stephenson, Tex. Univ. 

Pub. 4101, p. 212, pi. 40, figs. 1, 2; pi. 41, figs. 1-4.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 121

Incomplete, internal molds, small to medium size, 

from three localities in the Owl Creek formation of 

southeastern Missouri are referred to Cyprimeria alto, 

(Conrad), (USGS 16429, 16451, 19090). The species 

is described in Texas University Publication 4101 

(Stephenson, 1941, p. 212).

Types.—The whereabouts of the original type material is 

not known and it is probably lost. One topotype, USGS 707, 

USNM 128155; neotype (designated by Stephenson, 1941, 

p. 214), USNM 76664; 1 plesiotype from southeastern Missouri, 

USGS 16429, USNM 128156.

Range.—Upper part of Exogyra costata, zone (Maestrichtian) 

in the Atlantic and Gulf Coastal Plain.

Genus IEGUMEN Conrad, 1858 

legnmen ellipticum Conrad 

Plate 20, figures 5-7

1858. Legumen ellipticum Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 325, pi. 34, fig. 19.

(For synonymy through 1941 see Tex. Univ. Pub. 4101, 

1941, p. 215.)

Imprints of the shells of this species, though small, 

are nevertheless complete enough for satisfactory identification. They have been collected at three localities 

in Stoddard County, Mo. (USGS 16429+16452, 16430, 

16451). A description of the species is given in the 

Texas University publication cited above.

Types.—Holotype, from Owl Creek, Tippah County, Miss., collection of the Academy of Natural Sciences, Philadelphia. 

Topotype from Owl Creek, Miss., USGS 707, USNM 128158; 2 

plesiotypes from the Owl Creek formation of southeastern Missouri, USGS 16452, USNM 128157.

Range.—This species ranges through the Exogyra costata, 

gone in the Atlantic and Gulf Coastal Plain. Closely related, 

possibly identical, shells are present in the upper part of the 

E. ponderosa zone (Campanian) beneath the E. costata zone.

Genus TENEA Conrad, 1870 

Tenea parilis (Conrad) 

Plate 20, figures 8-11

1860. Mysia parilis Conrad, Acad. Nat. Sci. Phila. Jour., 2d ser., 

v. 4, p. 278, pi. 46, fig. 16.

(For synonymy through 1941 see Tex. Univ. Pub. 4101, 

1941, p. 217.)

Imprints of Tenea parilis (Conrad) are common in 

the Owl Creek formation of southeastern Missouri; 

the collections include specimens from four localities in 

Stoddard County (USGS 16429+16452, 16430, 16451, 

19090). The impressions are especially abundant at 

the road ditch exposure 1.4 miles west by slightly south 

of Ardeola station (USGS 19090). This small, smooth, 

subcircular bivalve is described in detail in Texas University Publication 4101 (Stephenson, 1941, p. 217) 

cited above.

Types.—The type of Mysia parilis Conrad (=Tenea parilis 

(Conrad)) is in the collection of the Academy of Natural Sciences, Philadelphia. It was collected by Dr. W. Spillman from 

Tippah County, presumably at the Owl Creek locality. One 

plesiotype (= topotype?), USGS 707, USNM 128160; 2 plesiotypes from the Owl Creek formation of southeastern Missouri, 

USGS 19090, USNM 128159.

Range.—Through the zones of Exogyra, ponderosa and E. 

costata (Campanian through Maestrichtian) in the Atlantic 

and Gulf Coastal Plain.

Superfamily TEIIINACEA

Family TELLINIDAE

Genus TELLINA Linne, 1758

Tellina buboana Stephenson, n. sp.

Plate 20, figures 12-14

The following description is based on the shells of 

two individuals from the Owl Creek formation on Owl 

Creek, Tippah County, Miss. (USGS 707). The larger 

of the two shells (holotype) includes both valves; the 

right valve is well preserved, but the left is broken and 

distorted in the umbonal region. The other shell 

(paratype) is a well-preserved valve with the hinge, 

uncovered.

Shell small, thin, subelliptical in outline, compressed, 

inequilateral, subequivalve. Lunule and escutcheon 

wanting. Posterodorsal slope narrow, flattened, descending rather steeply; shell flexed slightly to the 

right in the posterior region. Beaks small, nonprominent, slightly opisthogyrate, situated about 0.57 the 

length of the shell from the anterior extremity. Anterodorsal margin long, broadly arched, descending; 

anterior margin sharply rounded; ventral margin long, 

broadly arched; posterior margin subangulated below, 

with a short subtruncation inclined forward above; 

posterodorsal margin broadly arched, descending. 

Surface smooth and polished in the umbonal region, 

becoming sharply and nearly regularly lined concentrically toward the outer margins.

Dimensions measured on the right valve of the holotype : Length 15.5 mm, height about 10 mm, convexity 

about 2 mm.

Ligamental groove external, opisthodetic, narrow, 

about 2 mm long in the types. Hinge as seen in a paratype, a right valve, very narrow. Below the beak is a 

short, trigonal, deeply bifid cardinal tooth, slightly 

oblique to the rear; a short delicate anterior cardinal 

tooth is strongly oblique to the front and is separated 

from the posterior cardinal by a deep trigonal socket. 

About 2.5 mm back of the beak (partly broken away) 

is a short, thin lateral tooth separated from the margin 

by a shallow channel; about 1.2 nyn forward from the 

beak is a short, thin lateral tooth, observed when first 

uncovered, but broken away in preparation; between 

this lateral and the margin is a shallow channel that 

continues on to the front. Other internal features not
122 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

uncovered. The hinge of the left valve was not seen 

completely uncovered, but in a broken left valve of the 

holotype, a short, relatively prominent, deeply bifid 

trigonal cardinal tooth, slightly oblique forward, 

stands opposite the deep trigonal socket of the right 

valve.

The holotype and paratype of Tellina buboana from 

Owl Creek, Miss. (USGS TOT, USNM 20706) have 

been previously labelled Tellinimera eborea Conrad, but 

Conrad's original illustrations indicate a shell differing 

in form and outline from this new species. Besides, 

Conrad's (1860, p. 278, pi. 46, figs. 10, 14; 1870, p. 73) 

original descriptions of the two species he referred to 

Tellinimera are inadequate; he indicated the locality of 

the two species as "Ala.;" but according to Johnson 

(1905, p. 16) the original label accompanying the type 

of Tellinimera eborea indicates "Miss." There is therefore uncertainty as to both the geographic and stratigraphic position of the types of both T. eborea and 

T. limatula.

Tellinimera eborea Conrad was designated as type 

of Tellinimera by Gardner (1916, p. 695).

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USGS 707, USNM 20706; 1 paratype from the same source, 

USNM 128161. One figured paratype from the Owl Creek formation of southeastern Missouri, USGS 19090, USNM 128162; 1 unfigured paratype from the same source, USNM 128163.

Range.—Owl Creek formation of northern Mississippi and 

southeastern Missouri.

Genus IINEARIA Conrad, 1860

The features of the genus Linearia Conrad are described and discussed at some length by Stephenson 

(1941, p. 221). The type species is Linearia metastriata Conrad, from Eufaula, Ala. One of the distinguishing features of the genus is the pair of conspicuously 

elongated cardinal teeth in the right valve, extending 

obliquely forward and downward, in contrast to the 

short, trigonal, bifid cardinal in the right valve of Tellina Linne, which extends downward and is slightly 

oblique to the rear. One long oblique cardinal in the 

left valve of Linearia is received in the socket separating the pair of cardinals in the right valve. Species 

having sculpture ranging from nearly smooth to radial 

ribbing covering the whole surface have been referred 

to this genus. All of them have in common the pair of 

long cardinal teeth oblique forward in the right valve.

Linearia metastriata Conrad 

Plate 20, figures 17-25

1860. Linearia metastriata Conrad, Acad. Nat. Sci. Phila. Jour.

2d ser., v. 4, p. 279, pi. 46, fig. 7. 

1870. Linearia Conrad, Am. Jour. Conchology, v. 6, p. 73, pi. 3,

fig. 11.

1885. Linearia metastriata Conrad. Whitfield, U. S. Geol.

Survey Mon. 9, p. 165, pi. 23, figs. 6, 7?, 8. (Also issued

as N. J. Geol. Survey, Paleontology ser., v. 1.) 

1899. Linearia metastriata Conrad. Harris, La. State Exp. Sta.

Spec. Kept. 6, Geol. and Agr., pt. 5, p. 296, pi. 50, fig. 7. 

1905. Linearia metastriata, Conrad. Johnson, Acad. Nat. Sci.

Phila. Proc., v. 57, p. 16. 

1907. Linearia metastriata Conrad. Weller, N. J. Geol. Survey.

Paleontology ser., v. 4, p. 618, pi. 70, figs. 8, 9. 

1916. Linearia> metastriata Conrad. Gardner, Md. Geol. Survey,

Upper Cretaceous [Maryland], in W. B. Clark and

others, p. 699. 

1923. Linearia metastriata Conrad. Stephenson, N. C. Geol. and

Econ. Survey, v. 5, pt 1, p. 329, pi. 84, figs. 1-5. 

1926. Linearia metastriata Conrad. Wade, U. S. Geol. Survey

Prof. Paper 137, p. 93, pi. 31, figs. 1, 2. 

1926. Linearia ornatissima Weller. Wade, U. S. Geol. Survey

Prof. Paper 137, p. 94, pi. 30, figs. 6, 7. 

1941. Linearia metastriata Conrad. Stephenson, Tex. Univ.

Pub. 4101, p. 221.

The species Linearia metastriata Conrad is represented in the Owl Creek formation of southeastern Missouri by internal and external molds at three localities 

in Stoddard County (USGS 16430,16451,19090). The 

species is present in the Owl Creek formation at Owl 

Creek Tippah County, Miss., where specimens with the 

shell more or less completely preserved have been collected (USGS 707, USNM 20713). Rather full descriptions of the species are given in several of the papers 

cited in the synonymy.

The species is characterized by beautiful surface cancellation produced by regularly spaced, narrow, sharp 

concentric ridges, crossed transversely by radiating costae that differ markedly in strength on different parts of 

the surface. The strongest and most widely spaced 

radials are on the dorsal slopes, and the weakest and 

most closely spaced ones are in broad areas on the flanks. 

The intersections of the concentric and radiating ribs 

are marked by round-crested, beadlike nodes that enhance the attractiveness of the cancellation. The internal mold shown in plate 20, figure 22, a nearly fullgrown individual, measures: Length 14 mm, height 10 

mm, conxexity about 2.5 mm.

Perfectly preserved shells referred to this species are 

recorded from the Coon Creek tongue of the Kipley 

formation at the classic Coon Creek locality in McNairy County, Tenn. (Wade, 1926, p. 93, pi. 31, figs. 

1, 2). These shells show considerable individual variation in the coarseness of their surface ornamentation.

Types.—Holotype, from Eufaula, Ala., collection of the Academy of Natural Sciences, Philadelphia. Three plesiotypes from 

Owl Creek, Miss., USGS 707, USNM 20713; 3 plesiotypes from 

the Owl Creek formation of southeastern Missouri, USGS 19090, 

USNM 128164; 2 plesiotypes from the Coon Creek tongue of the 

Ripley formation at Coon Creek, McNairy County, Tenn. USGS 

10198, USNM 128165.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 123

Range.—Through the zones of Exogyra, ponderosa and E. costata (Campanian and Maestrichtian).

Superfamily SOLENACEA

Family SOLENIDAE

Genus LEFTOSOLEN Conrad, 1865

Leptosolen biplicatus (Conrad)

Plate 20, figures 15, 16

1858. Siliquaria biplicata Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 324, pi. 34, fig. 17. 

1865. Solena (Leptosolen) biplicata (Conrad), Acad. Nat. Sci.

Phila. Proc., v. 17, p. 184. 

1867. Leptosolen Mplicata (Conrad), Am. Jour. Conchology,

v. 3, p. 15,188.

1885. Leptosolen biplicata Conrad. Whitfleld, U. S. Geol. Survey Mon., 9, p. 183, pi. 25, figs. 1, 2. Also issued as

N. J. Geol. Survey, Paleontology ser., v. 1) 

1907. Leptosolen biplicata Conrad. Weller, N. J. Geol. Survey,

Paleontology ser., v. 4, p. 624, pi. 70, figs. 30, 31. 

1916. Leptosolen biplicata Conrad. Gardner, Md. Geol. Survey,

Upper Cretaceous [Maryland], in, W. B. Clark and

others, p. 703, pi. 42, figs. 7, 8. 

1923. Leptosolen biplicatus Conrad. Stephenson, N. C. Geol.

and Econ. Survey, v. 5, pt. 1, p. 332, pi. 85, figs. 10-13. 

1926. Leptosolen biplicata Conrad. Wade, U. S. Geol. Survey

Prof. Paper 137, p. 94, pi. 31, figs. 4, 7. 

1928. Leptosolen Mplicatus Conrad. Adkins, Tex. Univ. Bull.

2838, p. 167. 

71929. Leptosolen aff. L. biplicatus Conrad. Dane, Ark. Geol.

Survey Bull. 1, p. 40, pi. 8, fig. 7. (Illustration only.)

1940. Leptosolen biplicatus Conrad. Stephenson and Monroe, 

Miss. State Geol. Survey Bull. 40, p. 290, pi. 15, fig. 5. 

(Illustration only.)

1941. Leptosolen biplicatus Conrad. Stephenson, Tex. Univ.

Pub. 4101, p. 226, pi. 43, figs. 4, 5.

1944. Leptosolen biplicatus (Conrad). Bergquist, Jour. Paleontology, v. 18, no. 1, p. 23.

The species Leptosolen Mplicatus (Conrad) has been 

adequately described in several of the papers listed in 

the synonymy. The few imprints that represent the 

species in the Owl Creek formation of southeastern 

Missouri are small and incomplete (USGS 16430,16452, 

and 19090, in Stoddard County; USGS 16598 in Scott 

County). Well-preserved shells are common in the 

Owl Creek formation of Mississippi at Owl Creek, 

Tippah County, the type locality of the species. The 

adult shell (topotype) shown in plate 6, figure 15, 

measures: Length 53 mm, height 16mm, convexity 5 

mm.

Types.—Holotype, collection of the Academy of Natural Sciences, Philadelphia. One plesiotype from the Owl Creek formation of southeastern Missouri, USGS 19090, USNM 128166; 

1 plesiotype (=topotype) from the Owl Creek formation, Tippah 

County, Miss., USGS 707, USNM 128167.

Range.—Through the zones of Exoffyra ponderosa and E. 

costata (Campanian and Maestrichtian) in the Atlantic and 

Gulf Coastal Plain.

Superfamily MYACEA

Family CORBULIDAE

Genus CORBTTLA Lamarck, 1799, sensu lato

Corbula spp.

The family Corbulidae is represented in the Owl 

Creek formation of southeastern Missouri by a few 

poor imprints including both internal and external 

molds (USGS 16429 + 16452,16430,16451,19090). The 

Corbulidae from the Upper Cretaceous formations of 

Mississippi have not been critically studied, identified, 

and compared and it does not seem feasible for present 

purposes to attempt to assign specific names to the 

Missouri material.

Family SAXICAVIDAE

Genus FANOFE Menard, 1807

Fanope monmouthensis Gardner

Plate 21, figures 24-26

1916. Panope monmouthensis Gardner, Md. Geol. Survey, Upper 

Cretaceous [Maryland], in W. B. Clark and others, 

p. 722, pi. 45, figs. 4, 5.

One internal mold of a left valve of a juvenile example of Panope monmouthensis Gardner has been identified from the Owl Creek formation of southeastern 

Missouri (USGS 16451). The surface sculpture is impressed upon the mold and, compared with the early 

stage of a well-preserved shell from the Owl Creek 

formation of Mississippi, shows no essential difference. 

The shell is elongate, subelliptical in outline, plump, 

inequilateral, equivalve, widely gaping at the rear, 

slightly gaping at the front. Beaks nonprominent, 

nearly direct, incurved, approximate, situated about 

0.4 the length of the shell from the anterior extremity. 

The anterodorsal slope descends steeply and is slightly 

excavated. Dorsal margin straight; anterior margin 

subtruncated, inclined a little rearward; ventral margin 

broadly convex; posterior margin subtruncated, inclined rearward, rounding sharply into the dorsal margin above. The surface is roughly ornamented with 

concentric lamellae, ridges, and undulations, and fine 

intervening growth lines; over much of the surface 

there is developed a fine, almost microscopic covering 

of stipples and tiny nodes of irregular size. Lunule and 

escutcheon wanting. External ligament opisthodetic 

and relatively short. One shell from Owl Creek reveals 

a stout projection (chondrophore?), only partly uncovered, extending into the interior from beneath the 

beak.

Dimensions of the large shell from Owl Creek, Miss., 

shown in plate 21, figures 24,25: Length 110 mm, height 

62 mm, thickness about 42 mm.

Types.—Holotype, collection of the Maryland Geological Survey on deposit in the U. S. National Museum. One plesiotype
124 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

from Owl Creek, Tippah County, Miss., USGS 707, USNM 

128168; 1 plesiotype from the Owl Creek formation of southeastern Missouri, USGS 16451, USNM 128169.

Range.—Monmouth formation, Maryland; Owl Creek formation of Mississippi and southeastern Missouri.

Family GASTROCHAENIDAE

Genus GASTROCHAENA Spengler, 1783

Gastrochaena ripleyana Stephenson

Plate 21, figures 22, 23

1926. Gastrochaena americana Gabb. Wade, U. S. Geol. Survey

Prof. Paper 137, p. 99, pi. 32, figs. 5-7. 

1941. Gastrochaena ripleyana Stephenson, Tex. Univ. Pub. 4101,

p. 244, pi. 46, figs. 5-14.

One incomplete internal mold of a partly crushed 

tube of Gastrochaena ripleyana Stephenson was collected at one locality in the Owl Creek formation of 

southeastern Missouri (USGS 16452). A description 

of the species, preceded by a critical review of the introduction, subsequent usage, and validity of the generic 

name Gastrochaena Spengler, is given in my Texas 

University Publication 4101, p. 242-246 as cited above. 

The one available mojld from Missouri is the large end 

of a tube having a maximum diameter of 12.3 mm; the 

part of the tube represented is 23.5 mm long, and the 

smaller half is crushed to a minimum diameter of 7.5 

mm. No evidence of the shell that inhabited the tube is 

observable.

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USGS 707, USNM 76752. One plesiotype (=topotype), USGS 

75, USNM 128170; 1 plesiotype from the Owl Creek formation 

of southeastern Missouri, USGS 16452, USNM 128171.

Range.—Coon Creek tongue of Ripley formation of Tennessee. 

Owl Creek formation of Mississippi and southeastern Missouri. 

Nacatoch sand and Corsicana marl of the Navarro group, Texas. 

Age Maestrichtian, possibly in part Campanian.

Superfamily ADESMACEA

Family FHOLADIDAE 

Genus GONIOCHASMA Meek, 1864

In my previous comments on this genus (Stephenson, 

1941, p. 249) I mistakenly referred to the anterior rib of 

a pair of internal ribs that extend from the beak downward to the ventral margin as the internal umbonal 

ridge, whereas the posterior rib is the true internal 

umbonal ridge. The anterior rib of the pair is of variable strength on different individuals but appears to be 

recognizable on all adult specimens of Goniochasma 

scaphoides Stephenson from Texas; it appears to be 

absent on the types of Xylophaga stimpsoni Meek and 

Hayden, the genotype of Goniochasma Meek, which 

fact, together with the presence of a mesoplax on the 

Texas species, may be sufficient reason for considering 

the latter generically distinct from Goniochasma.

The mold from the Owl Creek formation of Missouri 

shows only one internal groove, not a pair of grooves,

and affords no evidence of a mesoplax above the beaks; 

it may therefore be a true Goniochasma.

GONIOCHASMA? sp. 

Plate 21, figure 1

The one internal mold from the Owl Creek formation 

of southeastern Missouri (USGS 19090) shows the impressions of a wide, angular hiatus in front, one internal 

umbonal rib, a strong internal posterodorsal rib, and 

fine concentric ribbing typical of that of Goniochasma 

Meek. The anterior part of the shell is inflated, the 

posterior part cuneate. The beaks are strongly incurved, prosogyrate and far forward. The mold measures : Length 12 mm, height about 6.5, convexity 4 mm. 

USNM 128172.

Class GASTROPODA 

Subclass STREPTONEURA 

Order CTENOBRANCHIATA

Suborder PIATYPODA

Superfamily PTENOG10SSA

Family ARCHITECTONICIDAE

Genus PSEUDOMALAXIS Fischer, 1885

Pseudomalaxis pateriformis Stephenson, n. sp.

Plate 21, figures 19-21

The external and internal molds of the bottom side 

of a nearly planispiral gastropod was collected at one 

locality in the Owl Creek formation of southeastern 

Missouri (USGS 19090), and is referred to the new 

species Pseudomalaxis pateriformis Stephenson, here 

described, which is based on one incomplete shell from 

Owl Creek, Tippah County, Miss. (USNM 20448).

Shell small, closely coiled; upper surface nearly flat, 

under surface very broadly and widely umbilicate 

(bowl-shaped). Protoconch smooth, coiled, slightly 

tilted. Whorls quadrangular in cross section. Outer 

angles of whorls densely beaded, the beads slightly 

elongated transversely. All outer surfaces covered 

with fine, rather obscure spiral lining; however, two 

or three of the lines on the inner side of the bead-rows 

on the upper of the two outer angles are a little larger 

than the others. The fine growth lines cross the bottom, 

outer edge, and top surfaces with a moderate obliquity 

toward the rear. Aperture not preserved but obviously 

quadrate. The greatest diameter of the incomplete 

holotype, as preserved, is about 13 mm.

The molds from Missouri apparently pertain to a 

specimen about as large as the holotype from Mississippi ; the sculpture has become somewhat obscured in 

the process of preservation but it appears to match that 

of the holotype except that it appears to be a little 

coarser.

This species is closely related to Pseudomalaxis pils- 

~bryi Harbison (1945, p. 81, pi. 1, figs. 5-7), but is much
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 125

larger, has a broader and shallower umbilical depression, and has much finer spiral sculpture.

A specimen from the Coon Creek tongue of the Bipley 

formation at the Coon Creek locality in McNairy 

County, Tenn., figured by Wade as belonging to his new 

species, Pseudomalaosis ripleyana, appears to be a 

juvenile example of P. pilsbryi Harbison; it does not 

belong to P. ripleyana.

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USNM 20448. One paratype from the Owl Creek formation, 

USGS 19090, USNM 128173.

Range.—Owl Creek formation of Mississippi and southeastern 

Missouri.

Super-family TAENTOGLOSSA

Family NATICIDAE

Genus POLINICES Montfort, 1810

Polinices reotilabrum (Conrad)

Plate 21, figures 10-12

1858. Natica (Lunatia) rectilabrum Conrad, Acad. Nat. Sci.

Phila. Jour., 2d ser., v. 3, p. 334, pi. 35, fig. 28. 

1926. Polinices (Euspira) halli (Gabb). Wade, U. S. Geol.

Survey Prof. Paper 137, p. 163, pi. 56, figs. 11, 12. 

1941. Polinices rectilabrum (Conrad). Stephenson, Tex. Univ.

Pub. 4101, p. 276, pi. 50, figs. 1-6.

One incomplete internal mold from the Owl Creek 

formation of southeastern Missouri (USGS 16451) is 

referred to Polinices rectilabrum (Gabb). In form it 

appears to be identical with topotypes of the species 

from Owl Creek, Tippah County, Miss. An account 

of the species and its distribution is given in Texas University Publication 4101 (Stephenson, 1941, p. 276, pi. 

50, figs. 1-6).

The species belongs to a group whose separation must 

depend on very slight consistent differences. There 

appears to be no essential difference between Polinices 

rectilabrum (Conrad) and the specimens referred by 

Wade (1926, p. 163) to Polinices (Euspira) tialli 

(Gabb) from Coon Creek, McNairy County, Tenn. 

P. umbilica Wade is also almost too close for separation, though the slight differences mentioned by Wade 

(1926, p. 163) may justify giving it a separate specific 

identity.

Types.—Conrad's original specimen is not listed as present in 

the collection of the Academy of Natural Sciences at Philadelphia and is presumed to be lost. In Texas University Publication 4101 as cited above, I figured a topotype from Owl Creek, 

Tippah County, Miss, and designated it neotype (USGS 707, 

USNM 76839) ; 1 figured topotype from Owl Creek, USGS 707, 

USNM 128210; 20 unfigured topotypes, USGS 707, USNM 20439. 

Plesiotype from the Owl Creelr formation of southeastern 

Missouri, USGS 16451, USNM 128174.

Range.—The range of specimens that appear to be inseparable 

from Polinices rectilabrum (Conrad) is through the zones of 

Ewogyra ponderosa and E. costata (Campanian through 

Maestrichtian).

Genus GYRODES Conrad, 1860

Gyrodes supraplicatus (Conrad)

Plate 21, figures 15, 16

1858. Rapa supraplicata Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 332, pi. 35, fig. 20.

(For synonymy through 1941 and description see Tex. 

Univ. Pub. 4101, 1941, p. 280.)

An incomplete internal mold of Gyrodes supraplicatus (Conrad) is present in one collection from the Owl 

Creek formation of southeastern Missouri (USGS 

16451). The specimen is identified by the form of its 

upper side and by the characteristic crenations that are 

rather weakly impressed upon the shoulder of the mold. 

In a well-preserved shell of the species the umbilicus is 

deep, flares outward at a wide angle, and is bordered by 

a crenulated carina; on the inner wall of the umbilicus 

a few millimeters away from the outer carina is a narrow less prominent, weakly crenulated spiral ridge.

Types.—The type specimen from Owl Creek, Tippah County, 

Miss., is presumed to be lost; topotype, USGS 707, USNM 128176. 

One plesiotype from the Owl Creek formation of southeastern 

Missouri, USGS 16451, USNM 128175.

Range.—Questionably from the upper part of the Eaogyra 

ponderosa zone through the E. costata zone in the Atlantic and 

Gulf Coastal Plain. Specimens from the former zone that have 

been referred to the present species on the basis of poorly preserved material may actually belong to nearly related species 

such as Gyrodes major Wade.

Gyrodes spillmanii Gabb 

Plate 21, figures 13,14

1860. Natica (Gyrodes) alveata Conrad, Acad. Nat. Sci. Phila. 

Jour., 2d ser., v. 4, p. 289, pi. 46, fig. 45. (Specific name 

preoccupied.)

1861. Gyrodes spillmanii Gabb, Acad. Nat. Sci. Phila. Proc.

(1861), v. 13, p. 320. 

1892. Gyrodes petrosus (Morton). Whitfield, U. S. Geol. Survey

Mon. 18, p. 127, pi. 16, figs. 1-4. (Also issued as N. J.

Geol. Survey, Paleontology ser., v. 2.) 

1905. Gyrodes spillmanii Gabb. Johnson, Acad. Nat. Sci. Phila.

Proc., v. 57, p. 21. 

1907. Gyrodes petrosus (Morton). Weller, N. J. Geol. Survey,

Paleontology ser., v. 4, p. 689. (In part; not the figured specimens.) 

1926. Gyrodes alveata Conrad. Wade, U. S. Geol. Survey Prof.

Paper 137, p. 164, pi. 57, figs. 6, 9. 

1941. Gyrodes spillmani Gabb. Stephenson, Tex. Univ. PuJ).

4101, p. 284, pi. 52, figs. 20, 21.

Incomplete internal and external molds of one individual from the Owl Creek formation of southeastern 

Missouri (USGS 19090) clearly show a well-developed 

shoulder carina paralleling the suture; this is the principal feature characterizing the species Gyrodes spillinanii Gabb. A full description of the species is given 

in Texas University Publication 4101, cited above.

Types.—Collection of the Academy of Natural Sciences of 

Philadelphia. One plesiotype from the Owl Creek formation of 

southeastern Missouri, USGS 19090, USNM 128177.
126 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Range.—As at present known the range of this species is 

through the Exogyra costata zone in the Gulf coastal plain.

Gyrodes sp. 

Plate 21, figures 17, 18

One internal mold from the Owl Creek formation of 

southeastern Missouri (USGS 19090) is referred to 

Gyrodes sp. The mold indicates a shell of about two 

and a half turns, a low spire and a rounded shoulder 

lacking a carina. The umbilicus is open though not as 

wide as in most species of Gyrodes. There probably 

was a weak carina on the rim of the umbilicus, but no 

carina on the inner wall. The mold measures: Height 

11+mm, diameter about 12.5 mm. USNM128178.

Family TURRITELLIDAE

Genus TURRITEIIA Lamarck, 1799, sensu lato

Turritella tippana Conrad

Plate 22, figures 20-22

1858. Turritella tippana Conrad, Acad. Nat. Sci. Phila., Jour.,

2d ser., v. 3, p. 333, pi. 35, fig. 19. 

71860. Turritella tippana Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 4, p. 285. 

1907. Turritella tippana Conrad. Weller, N. J. Geol. Survey,

Paleontology ser., v. 4, p. 700, pi. 79, figs. 6, 7. 

?1916. Turritella tippana Conrad. Gardner, Md. Geol. Survey,

Upper Cretaceous [Maryland], in W. B. Clark and

others, p. 491. 

1926. Turritella tippana Conrad. Wade, U. S. Geol. Survey

Prof. Paper 137, p. 162, pi. 56, fig. 9.

Imprints of Turritella tippana Conrad are abundant 

in the Owl Creek formation of southeastern Missouri 

(USGS 16430, 16451, 16597, 16598, 19090). Well-preserved shells of this species are abundant in the Owl 

Creek formation of Mississippi at the type locality on 

Owl Creek, Tippah County. The description is based 

mainly on the Mississippi shells.

Shell high turreted, imperforate; apical angle about 

20°. Protoconch not observed. Suture closely appressed, moderately impressed, situated at the bottom 

of a rather wide revolving sulcus. The whorls number 

13 or 14 on large adults and are ornamented with revolving sculpture that exhibits some individual variation in 

the strength of the ribs and in the presence or absence 

of small secondary ribs in the spaces between the larger 

ribs; there is, however, a general similarity in the form 

and sculpture of 11 shells from the type locality, such 

as to leave no doubt that they all belong to the same 

species. The shell shown in plate 22, figure 20, is one 

that was illustrated by Weller (1907, p. 700, pi. 79, fig. 

6), and the description of the sculpture here given is 

based mainly on that specimen.

The flank of each of the larger whorls bears four 

primary spiral costae; two of these form a pair on the 

lower half of the flank, separated from each other by a

flat relatively wide interval; above the pair at a narrower interval is a third smaller primary costa; and on 

the upper half of the flank above a wider slightly excavated interval is the fourth, which may or may not 

be a little more prominent than either of the other three. 

Closely paralleling the upper side of the lower suture 

is a low, narrow, weak secondary spiral, and between 

the uppermost primary and the suture above is a similar 

secondary spiral. Weak to obscure spiral lining, variable on different individuals, may be present in any of 

the intercostal areas. The growth lines are rather 

strongly convex forward on the base and periphery and 

concave forward above the periphery. The periphery 

bends sharply over to a steep, slightly convex base, 

which bears fine, more or less obscure, spirals that are 

coarsest near the periphery. The aperture is subcircular except that it is angulated at the rear. A thin 

callus is present on the parietal wall.

The sculpture as seen in the imprints from the Owl 

Creek formation of southeastern Missouri agrees essentially with that of the topotypes from Mississippi.

Conrad's original description of this species is brief 

and inadequate, and his illustration is inaccurate. The 

topotype from Owl Creek, which Weller figured, and 

which is refigured here, may be considered a neotype.

The specimen figured by Wade from the Coon Creek 

tongue of the Kipley formation, McFairy County, 

Tenn., exhibits sculpture quite similar to that of typical specimens except that the spiral costae are more 

sharply and more strongly developed; also the growth 

lines stand out more conspicuously giving to the surface a finely roughened appearance.

Types.—The whereabouts of Conrad's figured specimen is not 

known and it is presumed to be lost. Topotype, .USGS 707 

USNM 20419; 10 unfigured topotypes, USGS 707, USNM 

128180. Two plesiotypes from southeastern Missouri, USGS 

16451, USNM 128179.

Range.—The species ranges questionably from the upper 

part of the Exogyra ponderosa zone through the E. costata zone 

in the Atlantic and Gulf Coastal Plain. It is common in the 

Owl Creek formation of Mississippi and southeastern Missouri.

Turritella vertebroides Morton, sensu lato 

Plate 22, figures 16-19

1834. Turritella vertebroides Morton, Synop. Organ. Remains 

Cretaceous group, United States, Philadelphia, p. 47, 

pi. 3, fig. 13.

1892. Turritella vertebroides Morton. Whitfleld, U. S. Geol. 

Survey Mon. 18, p. 146, pi. 18, figs. 13-15, questionably 

ligs. 16-18. (Also issued as N. J. Geol. Survey, Paleontology ser., v. 2.)

3907. Turritella vertebroides Morton. Weller, N. J. Geol. Survey, Paleontology ser., v. 4, p. 693, pi. 78, fig. 15 (not 

fig. 14; questionably figs. 16, 17).

3923. Turritella vertebroides Morton. Stephenson, N. C. Geol. 

and Econ. Survey, v. 5, p. 366, pi. 91, figs. 11-14.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 127

1926. Turritetta vertebroides Morton. Wade, U. S. Geol. Survey 

Prof. Paper 137, p. 161, pi. 56, fig. 1.

Fossil imprints, both external and internal molds, 

identified as belonging to Tumtella vertebroides Morton, were found in the Owl Creek formation of southeastern Missouri at four localities (USGS16429+16452, 

16451, 16598, 19090). Morton's type specimen is a 

crushed shell including parts of two of the larger 

whorls, from "New Jersey." The sculpture is fairly 

well preserved on what appears to be the penultimate 

whorl, but the shell is too incomplete for satisfactory 

comparison with shells from the Gulf region. However, 

there is no question but that the sculpture as shown by 

the Missouri imprints is of the vertebroid sort and appears to be essentially like that of Morton's type specimen. Well-preserved shells of the species are common 

in the Owl Creek formation of Mississippi.

The species is characterized by a high turreted, uniformly tapering spire of 12 or 13 whorls and an apical 

angle of about 20°. The sides of the whorls are gently 

and uniformly convex and the suture is closely appressed in the bottom of a broad shallow depression. 

Some adult shells show a gerontic stage in which the 

body whorl becomes separated from the penultimate 

whorl and crowded coarse growth lamellae form an upraised apertural outer lip. The flanks of the body whorl 

bear four narrow primary spiral ridges, much narrower than the interspaces; these primaries may be uniformly spaced, or, as in most of the Missouri and Mississippi specimens, the space between the two upper 

primaries may be a little wider than the others; a secondary spiral lies a little below the upper suture, and 

a secondary forms a sharp peripheral ridge on the body 

whorl and is exposed immediately above the lower suture on the penultimate and earlier whorls.

The base is flat, very steep and nearly smooth, though 

microscopic spiral lirae may be detected on some specimens. The growth lines cross the base in a broad, curve 

concave toward the front and strongly oblique in that 

direction; at the periphery they swing sharply back and 

cross the flank above in a pronounced curve concave toward the aperture. The aperture is subcircular to 

broadly ovate and flares a little in the gerontic stage.

The dimensions of the specimen from Owl Creek, 

Miss., shown in plate 22, figures 16, 17, are: Height 68 

mm, maximum diameter 21 mm. The largest shell in 

the Owl Creek collection is 76.5 mm high.

Types.—Holotype, collection of the Academy of Natural 

Sciences of Philadelphia; the holotype is figured by Stephenson 

(1923, pi. 91, fig. 11). One plesiotype from Owl Creek, Tippah 

County, Miss., USGS 707, USNM 128181; 1 plesiotype from the 

Owl Creek formation of southeastern Missouri, USGS 16451, 

USNM 128182.

Range.—The known range of the species is through the Exogyra costata zone in the Atlantic and Gulf Coastal Plain.

Genus TROBUS Stephenson, n. gen.

Type species: Trobus buboanus Stephenson

Etymology.—By anagram from robust. Gender, masculine.

Shell large, thick, robust, high turreted, with spiral 

angle of about 13°. Whorls 18 or 20 (estimated), flat 

to slightly concave on the sides. Suture in a deep furrow that is squarish in cross section. The earlier whorls 

are smooth on the flank, the upper edge, however, projecting upward and overhanging the sutural furrow; at 

a diameter of about 20 mm the upper edge of the flank 

begins to swell outward and as growth proceeds this 

swelling gradually increases to a distinct narrow spiral 

ridge that borders and overhangs the sutural furrow; at 

a diameter of about 25 mm the lower border of the flank 

begins to swell outward and it too develops into a narrow prominent spiral; the upper spiral is irregularly 

undulating on the crest, and the lower is nearly smooth. 

The space between these two spirals is wide, flat, or 

slightly and broadly concave.

The base is steep, gently convex, and bears four moderately strong, evenly spaced spiral ridges that decrease 

slightly in strength downward; the upper one of these 

spirals is exposed on the penultimate whorl just above 

the lower suture. The trend of the growth lines on the 

base is slightly sinuous and nearly directly upward; 

they cross the flank above in a broad curve concave toward the aperture. The aperture is subcircular to 

broadly subovate, the outer lip is uniformly arched, and 

the inner lip forms a thick callus on the parietal w?ll.

Trobus buboanus Stephenson, n. sp. 

Plate 22, figures 23-25

The species, Trobus buboanus Stephenson appears to 

be represented in the Owl Creek formation of southeastern Missouri by a fragment of one distorted internal 

mold from Stoddard County (USGS 16452). The fragment pertains to the adult portion of a large turreted 

gastropod and is too imperfect for certain identification. 

However, no other turreted gastropod as large as T. buboanus is known in the Owl Creek formation and the 

reference of the fragment to this species is probably correct. The description of the species is based on the holotype from Owl Creek, Tippah County, the features of 

which are described in detail in connection with the description of the genus. The holotype is well preserved 

and includes the body whorl (outer lip broken) and 

four successively earlier whorls; the apex and younger 

part of the spire to a diameter of 16 mm are missing.

The dimensions of the incomplete holotype are: 

Height 111-f- mm, greatest diameter, measured on the 

most prominent spiral, 40 mm.
128 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

A large internal mold from the Eipley formation at 

Lander's Mill, Tippah County, Miss. (USGS 714) is 

referable to the genus Trobus, but is too incomplete for 

certain specific identification. However, a fragment of 

the external mold of the body whorl reveals surface features indicating very close relationship, if not specific 

identity with T. bitboanus.

Types.—Holotype, from the Owl Creek formation, Owl Creek, 

Tippah County, Miss., USGS 707, USNM 20423; a fragment of 

an internal mold, from the Owl Creek formation of southeastern 

Missouri, is provisionally identified as belonging to Trobus 

luboanus, USGS 16452, USNM 128184.

Range,—Known from the Owl Creek formation of Mississippi 

and Missouri, and questionably from the upper part of the 

Ripley formation in Tippah County, Miss.

Family APORRHAIDAE 

Genus ANCHTTRA Conrad, 1860, sensu lato

Anchura? spp. 

Plate 22, figures 10-12

Imprints of incomplete shells that probably belong to 

the Aporrhaidae and possibly to the genus Anchura 

(sensu lato) are in collections from three localities in 

the Owl Creek formation of southeastern Missouri 

(USGS 16429,16451,19090). The preservation is poor 

but enough of the sculpture is shown to suggest that 

three or more species are represented. Two of the imprints are illustrated in plate 22, figures 10-12. USNM 

128185 and 128186.

Genus HELICAULAX GABB, 1868

Helicaulax formosa Stephenson, n. sp.

Plate 21, figures 7-9

Imprints of several fragments of this species are in 

the collection from one locality in the Owl Creek formation of southeastern Missouri (USGS 19090). 

About a dozen fairly well preserved, though incomplete, shells from the Owl Creek formation on Owl 

Creek, Tippah County, Miss., afford the main basis for 

the description of the species.

The shell is of medium size, medium high turreted, 

with apical angle of about 25°. Whorls 10 to 12 in 

adults, moderately and uniformly convex on the side. 

Protoconch not well preserved. Suture closely appressed, moderately impressed. Body whorl elongate, 

broadly rounded on the periphery and base. Axial ribs 

numerous, narrow, separated by wider interspaces; on 

the larger whorls of the spire there are about 24 axials 

that trend with a slight obliquity rearward across the 

flank but bend forward above as they approach the 

suture. Each of the larger whorls of the spire bears 

four weak primary spiral ribs that produce beadlike 

nodes where they cross the axials; these primaries become weaker rearward and are wanting on the early

apical whorls; the side of each whorl is covered with 

fine, closely spaced spiral lirae that override the axials. 

The body whorl bears 7 or 8 primary spiral ribs that 

produce more prominent nodes where they cross the 

axials than are present on the whorls of the spire above; 

the second primary rib below the suture increases in 

prominence as it approaches the aperture.

The aperture is elongate-lanceolate, acutely angular 

at the rear, and extends far forward as a narrow 

siphonal channel in a nearly straight spinelike beak. 

In mature shells the outer lip expands forward to form 

a broad winglike extension of somewhat variable outline on different individuals; the upper part of this 

wing is produced forward and upward spurlike and 

bears a narrow sharp ridge; this ridge is the forward 

continuation of the prominent primary rib on the body 

whorl, previously mentioned. The inner lip forms a 

rather thick band of callus that, in mature shells, extends spinelike up the side of the spire, toward the 

top of which it is deflected away from close contact 

with the whorls; the anal channel traverses this band 

of callus.

Dimensions of the holotype: Height, tip of apex to 

tip of beak, about 41 mm; diameter, exclusive of expanded wing about 10 mm; including expanded wing, 

24mm.

The Missouri material, though incomplete, reveals 

enough features for satisfactory identification. The 

form of the shell, the ornamentation, and the expanded 

winglike outer lip appear to be identical with the types 

from Owl Creek, Miss.

Types.—Holotype, from Owl Creek, Tippah County, Miss., 

USGS 707, USNM 128189; 7 paratypes from Owl Creek, USNM 

20434; 2 figured paratypes from the Owl Creek formation of 

southeastern Missouri, USGS 19090, USNM 128187; 1 unfigured 

paraptype from the same source, USNM 128188.

Range.—Known only from the Owl Creek formation of 

Mississippi and southeastern Missouri.

Superfamily RACHIGLOSSA

Family PYROPSIDAE

Genus NAPTTLTTS Stephenson, 1941

Napulus octoliratus (Conrad)

Plate 21, figures 2-5

1858. Ficus octoliratus Conrad, Acad. Nat. Sci. Phila. Jour.,

2d ser., v. 3, p. 332, pi. 35, fig. 6.

71941. Napulus octoliratw (Conrad). Stephenson, Tex. Univ. 

Pub. 4101, p. 320, pi. 60, figs. 7, 8.

Internal molds of three examples of Napulus octoliratus (Conrad), all incomplete, are present at one 

locality in the Owl Creek formation of southeastern 

Missouri (USGS 19090). The external spiral ribbing 

of the whorls is rather weakly impressed upon the 

molds. The shell described by Conrad came from the
OWL CREEK FOSSILS FROM CROWLETS RIDGE, SOUTHEASTERN MISSOURI 129

Owl Creek formation at Owl Creek, Tippah County, 

Miss., and two topotypes from that locality are here 

figured (pi. 21, figs. 2,3).

Shell small, thin, pyriform, with a low spire having 

an angle of about 95°. Protoconch smooth, low turbinate, coiled about one and a half turns. The body 

whorl is plumply rounded and bears six nearly evenly 

spaced primary spiral ribs having flattish to broadly 

rounded crests; the interspaces are about three times 

as wide as the ribs are thick and are smooth or bear 

obscure spiral lining; low on the base and on the upper 

part of the siphonal extension (beak) are 3 or 4 revolving ribs of secondary strength. Axial ribbing is wanting. Aperture broadly lanceolate with an acute angle 

at the rear and a narrow siphonal channel traversing a 

long nearly straight beak at the front. Outer lip evenly arched; inner lip forming a thin layer of callus 

extending well forward on the parietal wall.

The internal molds of the three specimens from the 

Owl Creek formation of Missouri appear to be identical in form with the topotypes from Mississippi, and 

have closely similar sculpture impressed upon them.

Types.—The whereabouts of Conrad's type specimen is unknown and is presumed to be lost. Two topotypes from Owl 

Creek, Tippah County, Miss., USGS 707, USNM 128190; 2 

plesiotypes from the Owl Creek formation of southeastern 

Missouri, USGS 19090, USNM 128191.

^Range.—The species has been identified from the Owl Creek 

formation and the Prairie Bluff chalk (Maestrichtian) of 

northern Mississippi and from the Owl Creek formation of 

southeastern Missouri; it has been questionably identified 

from the Kemp clay of the Navarro group (Maestrichtian) of 

Texas.

Wapulus? sp. 

Plate 21, figure 6

One shell referred to Napulusf sp., from the Owl 

Creek formation of southeastern Missouri, is represented by incomplete internal and external molds 

(USGS 16451). It is probably an undescribed species, 

but is too poorly preserved to serve as a type. It is 

about the same size as Napulus octoliratus and possesses about the same number of revolving ribs, but these 

ribs are weakly noded. The incomplete penultimate 

whorl indicates that the spire is higher than the spire of 

Napulus, and the specimen may belong to a different 

genus. USNM 128192.

Family MOREIDAE

Genus MOREA Conrad, 1860

Morea transenna Stephenson, n. sp.

Plate 22, figures 6-9

Shell of medium size and has about four rapidly expanding whorls. Spire low with an apical angle of

about 90°. Protoconch rather high turbinate, coiled 

one and a half or two times. Suture deeply impressed, 

closely appressed in earlier stages, opening out a little 

in adults. Body whorl large, with a pronounced narrow shoulder above, the surface rounding down broadly 

from shoulder to base. The surface of an adult body 

whorl bears from top to bottom 11 pronounced squaretopped spiral ribs, separated by interspaces of equal or 

greater width than the ribs. The axial ribs are numerous, closely spaced and form squarish nodes where they 

intersect the spirals. The spiral rib at the shoulder 

angle is thicker than any of the others and is separated 

from the uppermost spiral by a relatively wide excavated interspace. Three spirals are exposed between sutures on the earlier whorls and a fourth spiral may appear above the lower suture of the penultimate whorl 

as the coiling of the body whorl becomes looser. Aperture elongate-lanceolate with a short anal notch at the 

rear and a rather wide siphonal notch at the front. 

Outer lip broadly arched, notched at the ends of the 

ribs; inner lip forming a callus that spreads forward 

somewhat on the parietal wall above, but opens out to 

form a rather wide umbilical fissure below. A narrow, 

sharp, twisted columellar fold lies just above the siphonal canal.

The holotype, which is shortened a little by a break 

at the forward end, measures: Height 22 + mm, diameter 14 mm. A small, nearly complete paratype (pi. 

22, fig. 8) measures: Height 12.5 mm, diameter 8 mm.

The species is more similar to Morea marylandica 

Gardner (1916, p. 466) than it is to any available species 

of Morea. Compared with the Maryland species M. 

transenna has more numerous and closely spaced axials, 

thus producing a finer sculpture pattern at the same 

growth stages, and its shoulder droops at a much steeper 

angle.

One incomplete external mold from the Owl Creek 

formation of southeastern Missouri (pi. 22, fig. 9) pertains to an immature individual of Morea transenna 

that is about as large as the figured paratype from Owl 

Creek, Miss. (USGS 19090).

Types.—Holotype, from the Owl Creek formation on Owl 

Creek, Tippah County, Miss., USGS 707, USNM 128194; paratype from the same source, USNM 20443; 1 paratype from the 

Owl Creek formation of southeastern Missouri, USGS 19090, 

USNM 128193.

Range.—So far as known this species is restricted in range 

to the Owl Creek formation (Maestrichtian) of Mississippi and 

Missouri. However, closely related species occur in the Ripley formation and beds of Ripley age in the Gulf region and as 

far north in the Atlantic Coastal Plain as the Monmouth formation of Maryland.
130 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Family FASCIOLARIIDAE 

Genus FUSINUS Rafinesque, 1815

Fusinus? sp. A 

Plate 22, figure 13

The internal mold of one small gastropod having 

the external sculpture impressed upon it, from one 

locality in the Owl Creek formation of southeastern 

Missouri (USGS 19090) has form and ornamentation 

that suggests the genus Fusinus Rafinesque. Its distinguishing features are a medium low spire, with 

spiral angle about 40°, short plump whorls, seven short, 

narrow, prominent, widely spaced axial ribs, numerous 

weak spiral ribs that override the axials, and a long 

straight beak. The suture is deeply impressed and 

there is no collar band. The -dimensions are: Height 

13+ mm, diameter 6 mm. No shell matching this one 

is present in our collections from the Owl Creek formation of Mississippi, and the mold appears to represent 

an undescribed species. USNM 128195.

Fusinus? sp. B 

Plate 22, figure 14

The incomplete external mold of a small gastropod 

from the Owl Creek formation of southeastern Missouri (USGS 19090) is referred questionably to Fusinus Rafinesque. The spire is short with an angle of about 

50°. The whorls are plump and bear prominent axial 

ribs and small, weak to obscure spiral ribs. A narrow 

shoulder is produced by a constriction below the suture. 

On the body whorl the axial ribs number 7 or 8, are 

separated by wider interspaces, extend down over the 

rounded periphery, and fade out about halfway down 

the base. A narrow collar band below the suture bears 

small nodes of irregular strength and even spacing. 

Four or five spiral ribs of medium strength and even 

spacing are on the base below the ends of the axial ribs. 

The mold as preserved measures: Height 8+ mm, 

diameter 5 mm. The mold probably pertains to an 

undescribed species. USNM 128196.

Family VOLUTIDAE

Genus LIOPEPLUM Ball, 1890

Liopeplum rugosum Stephenson, n. sp.

Plate 22, figures 1-5

1890. Liopeplum su'bjugosum Ball (not Gabb), Wagner Free 

Inst Sci. Trans., v. 3, pt. 1, p. 83, pi. 6, fig. 12a.

Three incomplete internal molds from the Owl Creek 

formation of southeastern Missouri (USGS 16451) 

are here referred to the new species, Liopeplum rugosum Stephenson. The description of the species is 

based on shells more or less completely preserved from

the Owl Creek formation of Tippah County, Miss. 

The species is characterized by the medium height of 

its spire of 4 or 5 whorls, its elongated body whorl, the 

coarse, thick, short axial ribs on the upper part of the 

body whorl and on the exposed parts of the earlier 

whorls, the thick ridge of bluntly nodose callus on the 

lower part of the penultimate and earlier whorls, the 

anal canal that follows the line of the suture just below 

the ridge of callus, the three or four columellar plaits 

mounted on a thickened part of the callus on the lower 

part of the inner lip, and the bright glaze that covers 

the entire shell. Where not covered with callus a few 

spiral threads may be seen on the outer surface near 

the forward end of the shell.

The three incomplete internal molds from Missouri 

agree in form with Liopeplum rugosum, and the axial 

ribs, which also seem to agree in number and spacing, 

are weakly impressed upon the molds. The largest of 

the molds measures: Height 32+mm, diameter 17.5 

mm.

The shell from Coon Creek, referred by Wade (1926, 

p. 118) to Liopeplum subjugosum (Gabb) differs from 

L. rugosum in several of its features. The axials are 

shorter, and, though present in medium strength on 

the penultimate whorl, they are much more numerous 

and become successively weaker forward on the body 

whorl, and on adults they fade out to a smooth surface 

before reaching the aperture; the ridge of callus above 

the suture is smoother and more uniformly developed, 

and the columellar plaits are fewer, weaker, and are 

not mounted on a thickened part of the inner lip. These 

differences seem to justify treating the Coon Creek 

shells as specifically different from those from Owl 

Creek. There is also the added consideration that the 

Coon Creek shells are from the Coon Creek, or basal, 

tongue of the Ripley formation, whereas the Owl Creek 

shells are from the Owl Creek formation which overlies 

the Ripley formation.

Nomenclatorial considerations require that an explanation be given as to why the name Liopeplum subjugosum Dall cannot be validly used for the species 

here described. In 1855 a species, Valuta, jugosa, was 

described by Tuomey (1855, p. 169). Gabb (1861, 

p. 149) found that the name V. jugosa was preoccupied 

by Sowerby and he renamed Tuomey's species V. subjugosa. There is no indication in Gabb's paper that 

he saw Tuomey's material; he merely substituted in 

a list the new name for the preoccupied specific name 

jugosa.

Tuomey's type material came from "Noxubie" 

County, Miss. His description of both the fossils and
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 131

the localities at which they were collected are inadequate, he published no illustrations, and his types are 

lost. The zonal source of his species, Valuta jugosa, is 

unknown because outcrops in Noxubee County include 

Upper Cretaceous beds ranging in age from Santonian 

to Maestrichtian. Dall (1890, p. 83) described and 

figured a shell from Tippah County, Miss., to which he 

applied the name Liopeplum subjugosum Dall. In attaching Ms own name as author of the species he seems 

to recognize the uncertainty of the identity of the shells 

from Tippah and Noxubee Counties. In reality he 

treats the Tippah County specimens as previously undescribed and assumes responsibility for the name 

which he applies to them. Actually there is no basis, 

other than Tuomey's brief description, for concluding 

that the shells from Tippah and Noxubee Counties are 

specifically identical. In view of these facts it seems 

necessary to conclude that the name L. subjugosum, as 

of Dall, is preoccupied by L. subjugosum (Gabb). This 

is the interpretation here accepted and the new name, 

L. Tugosum Stephenson is proposed for the Tippah 

County shells.

Dall recorded the source of his Liopeplum subjugosum as "the Bipley sands of Tippah Co., Miss., Mr. 

Stanton." The "Bipley sands" as used at that time 

(1890) included the Ripley and Owl Creek formations 

of the current classification. There is nothing in our 

records to show whether Dall's figured specimen came 

from the Ripley or from the Owl Creek. However, 

his type specimen agrees closely in its features with 

the primary types of my new species, Liopeplum rugosum, which are from the Owl Creek formation at Owl 

Creek, Tippah County, and the assumption seems justified that Dall's type came from the Owl Creek formation, probably from the Owl Creek locality; the name 

L. subjugosum Dall seems therefore properly to belong 

in the synonymy of L. rugosum Stephenson.

Types.—Holotype, from Owl Creek formation, Owl Creek, 

Tippah County, Miss., USGS 707, USNM 128200; 1 paratype 

from same source, figured, USNM 128190. Two figured paratypes from the Owl Creek formation of southeastern Missouri, 

USGS 16451, USNM 128198; 1 unfigured paratype from the 

same source USNM 128197.

Range.—As here restricted the species is known only from 

the Owl Creek formation of Mississippi and Missouri.

Genus DBILLUTA Wade, 1916

Drilluta sp. 

Plate 22, figure 15

The internal mold of about half a turn of the body 

whorl of a gastropod from the Owl Creek formation 

of southeastern Missouri (USGS 16429), appears to 

pertain to the genus Drilluta Wade. The sculpture as

it is impressed upon the mold includes eight axial ribs 

that extend well down over the base, and each rib bears 

a weak node at its upper end; 8 or 9 weak to obscure 

spirals are present and override the axials. The sculpture resembles that of Drilluta ripleyana (Conrad) 

except that the axial ribs appear to be more numerous 

and closely spaced. USNM 128201.

A similar specimen from another locality in Missouri 

(USGS 19090) has about the right number of axial ribs 

to match D. ripleyana^ but the specimen is too poorly 

preserved for certain identification. USNM 128202.

Genus VOLUTOMORPHA Gabb, 1877

Volutomorpha? spp.

Plate 23, figures 1, 2

Fossil molds of gastropods from two localities in the 

Owl Creek formation of Stoddard County, Mo., are 

referred questionably to Volutomorpha Gabb. The 

specimens from the two localities may belong to the 

same species, but their specific identity is not established. The specimen from one of the localities (USGS 

14651) is the internal mold of a medium-sized shell 

with a rather high spire and a spiral angle of about 

35° (pi. 23, fig. 2). The suture is deeply impressed. 

Three whorls are preserved and have impressed upon 

them thick strong axial ribs separated by interspaces 

that are about as wide as the ribs are thick; the axials 

number 9 or 10 on each of the whorls; on the body whorl 

the axials die out downward about at the periphery. 

Ten spirals are rather distinctly impressed on the 

lower part of the body whorl, the lower 5 are coarser 

and more widely spaced than the upper 5. This incomplete mold measures: Height 43+ mm, diameter about 

24mm. USNM 128204.

The other locality (USGS 19090) yielded the internal and external molds of part of the body whorl of 

one individual (pi. 23, fig. 1). Three short thick axial 

ribs are present on the upper part of this fragment, and 

the whole surface is ornamented with 15 revolving ribs 

the lower 5 of which are stronger and more widely 

spaced than the other ribs higher on the shell. The 

upper 5 or 6 spirals override the axials, and in the interspaces these spirals are weakly nodose. USNM 128203.

Family HARPIDAE 

Genus EOHARPA Stephenson, n. gen.

Type species: Eoharpa sinuosa Stephenson.

Etymology.—Greek eo, early; Harpa, a gastropod 

genus.

The new genus Eoharpa is a medium-sized gastropod 

with a low spire of 3 or 4 whorls, a moderately plump 

body whorl constricted anteriorly and extending well
132 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

forward as a markedly sinuous beak and siphonal canal. 

The surface ornamentation consists of long, narrow, 

sharp, widely spaced axials that extend to the base of 

the whorl, and numerous weak, evenly spaced sharpcrested spirals that are narrower than the interspaces. 

The aperture is long and narrow and the inner lip forms 

a rather thick band of callus extending well forward on 

the parietal wall and beak; small tubercles of irregular 

size, shape and distribution stipple a band several millimeters wide on the callus near its forward margin.

Eoharpa sinuosa Stephenson, n. sp. 

Plate 23, figures 3-6

Shell of medium size, pyrif orm, with a low spire of 3 

or 4 whorls; spiral angle about TO 0 . Protoconch not 

preserved. Suture moderately impressed. Body whorl 

plump above, rounding broadly down over the periphery to the base; shoulder narrow, poorly defined, with 

a slight narrow crinkled overlap on the side of the 

whorl above. Axial ribs long, narrow, sharp, widely 

spaced, above extending across the shoulder with diminishing strength to the suture; 12 axials are on the 

body whorl and 11 on the penultimate whorl. The 

spiral ribs are very subdued, regularly spaced and narrower than the interspaces.

Aperture elongate-lanceolate, acutely angular at the 

rear and extending forward as a narrow, siphonal canal 

in a long sinuous beak. The outer lip, which is not complete, is thin and broadly arched; the inner lip forms a 

wide band of callus on the parietal wall and beak; it 

is broadly concave in its upper half and sinuous below. 

Tubercules of irregular size, shape, and distribution 

ornament the callus covering in a band just back of its 

forward margin. The columella is strongly twisted 

and apparently without plaits.

Dimensions of the holotype: Height 24+mm, diameter about 11 mm; length of aperture, including siphonal canal, 19 mm.

An external mold that includes part of the body 

whorl and part of the penultimate whorl of a shell of 

Eoharpa sinuosa (pi. 23, fig. 6) is present in the collection from one locality in the Owl Creek formation of 

southeastern Missouri (USGS 19090) ; accompanying 

the outer mold is the internal mold of part of the body 

whorl. These molds pertain to an individual that has 

a diameter of at least 17 mm, and is therefore considerably larger than the holotoype from Mississippi.

Types.—Holotype, from the Owl Creek formation, Owl Creek, 

Tippah County, Miss., USGS 707, USNM 20400; one paratype 

from the Owl Creek formation of southeastern Missouri, USGS 

19090, USNM 128205.

Range.—Known only from the Owl Creek formation of Mississippi and Missouri.

Superfamily TOXOGLOSSA

Family CANCELLARIIDAE

Genus CAVEOLA Stephen son, 1941

Caveola sp. 

Plate 23, figure 7

The external and internal molds of a small gastropod from the Owl Creek formation of southeastern 

Missouri (USGS 19090) appears to be referable to 

Caveola Stephenson. The spire is of medium height 

with a spiral angle of about 30°. The sutures are deeply 

impressed. The whorls are moderately convex on the 

side. The body whorl is broadly convex from the illdefined shoulder above to the base, with no indication 

of an angle at the periphery; a slight steepening of the 

surface above as it rounds down to the suture is suggestive of a narrow shoulder.

The surface of the shell above the periphery is ornamented with a network of revolving riblets crossed by 

similar axial riblets; the axial riblets die out on the base 

below the periphery but the spirals continue well developed to the base. The aperture is elongate-lanceolate, ending anteriorly in a short open siphonal canal. 

The columella bears at least two prominent plaits somewhat below the base of the parietal wall. The dimensions of the shell are: Height apex to end of beak 25 

mm; diameter 5 mm. USNM 128206.

This shell resembles rather closely the species, 

Caveola producta Stephenson, from the Nacatoch sand 

of the Navarro group (Maestrichtian), Texas (Stephenson, 1941, p. 364, pi. 7, figs. 11, 12). The details of 

sculpture and form are, however, not well enough shown 

in the one available specimen to justify referring it to 

the Texas species.

Order OPISTHOBRANCHIA 

Suborder TECTIBRANCHIATA

Family ACTEONIDAE 

Genus EOACTEON Stephenson, n. gen.

Type species: Solidulus linteus Conrad

Etymology.—Greek eo, early; Acteon, a gastropod genus

The new genus Eoacteon is similar to and closely 

related to the Kecent Acteon Montfort, but differs 

mainly in the features of the columella. In Acteon 

there is a conspicuous columellar fold that reaches the 

aperture in strength; in Eoacteon there is a corresponding but much weaker fold and in addition there is a 

second and still weaker fold low on the columella just 

above and parallel to the siphonal canal. The Recent 

genus Solidula Fischer appears to be closely related to 

Eoacteon, but it too possesses a conspicuous columellar 

fold that reaches the aperture. Fictoacteon Stephenson, a genus represented by several species in the Wood-
OWL CREEK FOSSILS FROM CROWLETS RIDGE, SOUTHEASTERN MISSOURI 133

bine formation (Cenomanian) of Texas, appears to 

possess a smooth columella.

Eoacteon linteus (Conrad) 

Plate 23, figures 8-10

1858. Solidulus linteus Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 334, pi. 35, fig. 10.

The species Eoacteon linteus (Conrad) is represented 

in the Owl Creek formation of southeastern Missouri 

by one internal mold on which the surface sculpture is 

weakly impressed (USGS 19090). One of several 

shells from Owl Creek, Tippah County, Miss., the type 

locality of the species is nearly complete and is available for comparison and description. Shell rather 

small, lanceolate in outline, moderately inflated, with 

about six rapidly expanding whorls. Spire short with 

spiral angle of 45°. Body whorl nearly twice as long 

as the spire is high, broadly rounded from suture above 

to base. Suture closely appressed in a shallow depression.

Surface ornamented all over with numerous flattopped spiral ribs of differing width, separated by 

narrow, shallow, finely punctate grooves. Aperture 

elongate, narrow above, ending at the rear in a narrowly 

acute angle, widening below and ending in front in a 

sharply rounded margin. Outer lip thin, broadly 

arched; inner lip lacking callus at the upper part of the 

aperture, with callus appearing low on the parietal 

wall and extending as a slightly upraised rim to the 

anterior margin. Columella with one relatively weak 

fold just below the base of the parietal wall, and a second still weaker fold low on the columella just above 

and parallel to the siphonal canal.

Dimensions of the figured topotype: Height 17.3 mm, 

diameter 7.6 mm; length of aperture 11.5 mm.

The internal mold from Missouri is not quite as large 

as the figured topotype but agrees with it in form and 

sculpture. It is 13.7 mm high and 6.2 mm in diameter.

The shell from the Monmouth formation of Maryland, referred to this species by Gardner under the name 

Acteon linteus (Conrad), (1916, p. 397), although 

closely related, appears to be more slender in profile, 

with a slightly higher spire, and should probably be 

treated as specifically distinct. The shell from the 

Coon Creek tongue of the Eipley formation referred 

by Wade (1926, p. 101) to the species, has a slightly 

higher spire and is less inflated on the upper part of 

the body whorl; these differences are slight but if 

persistent would seem to justify specific separation.

Types.—Conrad's type material is apparently lost, but the 

specimen shown in plate 23, figures 8, 9 (USGS 707, USNM 

128208), is from the type locality on Owl Creek, Tippah County, 

Miss.; it is believed to be a topotype. One plesiotype from the

Owl Creek formation of southeastern Missouri, USGS 19090, 

USNM 128207.

Range.—So far as at present known the species, as here 

restricted, is confined to the Owl Creek formation of Mississippi 

and Missouri. However, very closely related forms occur in 

the stratigraphically lower Ripley formation and in the 

Monmouth formation of Maryland.

Family BTTLIABIIDAE

Genus BTJLIOPSIS Conrad, 1858

Bullopsis cretacea Conrad

Plate 23, figures 11-19

1858. Bullopsis cretacea Conrad, Acad. Nat. Sci. Phila. Proc.,

2d ser., v. 3, p. 334. 

1860. Bullopsis cretacea Conrad, Acad. Nat. Sci. Phila. Proc.,

2d ser., v. 4, p. 298, pi. 46, fig. 27. (No text description.)

One internal mold of a medium-sized shell, 4 internal 

molds and 1 external mold probably representing youthful stages of the same species, from 1 locality in the Owl 

Creek formation of southeastern Missouri (USGS 

19090), are referred to Bullopsis cretacea Conrad. The 

description which follows is based mainly on a collection of many well-preserved shells from the type 

locality on Owl Creek, Tippah County, Miss.

Shell small, involute, broadly subovate in vertical 

profile, with spire sunken in a shallow depression. Protoconch small, smooth, tilted. The shell expands rapidly and the body whorl is large. Superficially the 

surface appears smooth but fine spiral grooves may be 

seen under a magnifying lens; these grooves range in 

strength, on different individuals, from fairly plain on 

some to obscure on others; the grooves also range in 

number and spacing on different shells, from many 

closely spaced, to fewer more widely spaced. Typically 

they are relatively widely spaced, numbering 25 or 30 

on the body whorl. The aperture is as long as the shell 

is high; it is narrow but rounded at the posterior end, 

widens considerably toward the front and is rounded on 

the front margin. Outer lip thin and broadly arched; 

inner lip forming a thin wash of callus above on the 

parietal wall, thickening below where it bears two prominent columellar folds.

Dimensions of the adult shell shown in plate 23, figures 11, 12: Height 18 mm, diameter 13.4 mm.

The one medium-sized internal mold from Missouri 

(pi. 23, figs. 17, 18) has the typical form of Bullopsis 

cretacea but does not bear the impressions of external 

grooves. Obscure traces of the grooves can be seen on 

one of the juvenile internal molds, and the grooves are 

clearly shown on the external mold of one small shell 

(pi. 23, fig. 19).

Types.—Holotype, from Owl Creek, Tippah County, Miss., collection of the Academy of Natural Sciences Philadelphia. Three 

figured topotypes, USGS 594, USNM 128221; 2 figured topotypes,
134 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

USGS 707, USNM 128211. Two plesiotypes from the Owl Creek 

formation of southeastern Missouri, USGS 19090, USNM 128209. 

Many topotypes are present in the National Museum collection, 

USNM 21685 (USGS 594), and USNM 20438 (USGS 707). 

Range.—Owl Creek formation of Mississippi and Missouri.

Family SCAPHANDBJDAE

Genus CYLICHNA loven, 1846

Cylichna ,sp.

Two internal molds of a small gastropod from the 

Owl Creek formation in southeastern Missouri (Scott 

County, USGS 16598; Stoddard County, 19090) appear 

to belong to Cylichna Loven. They are similar in form 

to shells from the Upper Cretaceous that have been referred to Cylichna recta (Gabb) by Weller (1907, p. 

814), Gardner (1916, p. 411), and Wade (1926, p. 106). 

However, Gabb's species came from the so-called "Green 

Marl" of New Jersey, a geologic unit later named Hornerstown marl, and now known to be of Eocene age. The 

specific identification by the authors cited is therefore 

questioned. The molds pertain to small, slender, completely involute shells that do not show the impressions 

of surface sculpture. The largest of the two molds 

measures: Height 6.5 mm, diameter 3.4 mm. USNM 

128212 and 128213.

Class CEPHALOPODA

Subclass TETRABRANCHIATA

Order AMMONOIDEA

Family BACTTLITIDAE

Genus BACUXITES Lamarck, 1799

Baculites carinatus Morton

Plate 24, figures 5-9

1834. Baculites carinatus Morton, Synopsis of the organic remains of the Cretaceous group of the United States, 

p. 44, pi. 13, fig. 1.

1858. Baculites tippaensis Conrad, Acad. Nat. Sci. Phila. Jour., 

2d ser., v. 3, p. 334, pi. 35, fig. 27.

1858. Baculites spillmani Conrad, Acad. Nat. Sci. Phila., Jour., 

2d ser., v. 3, p. 335, pi. 35, fig. 24.

The presence of Baculites Lamarck in the Owl Creek 

formation of southeastern Missouri is shown by fragmentary external and internal molds pertaining to early 

stages of growth, at two localities (USGS 16451 and 

16452). One of the external molds reveals three features that permit its identification with Baculites 

carinatus Morton the type of which came from the 

Prairie Bluff chalk at Prairie Bluff, Wilcox County, 

Ala. Morton's figured type is an incomplete internal 

phosphatic mold about 50 mm long, measuring in its 

dorsoventral diameter about 15 mm at the small end 

and 18 mm at the large end.

The species is represented by numerous incomplete 

examples from Owl Creek, Tippah County, Mo. 

(USGS 707, USNM 20862), most of which retain all or

parts of the shell. They are all more or less distinctly 

carinated on the ventral side. The features preserved 

on the one external mold (USGS 16452) mentioned in 

the preceding paragraph include first, two weak ribs 

on the flank, which herald the larger, stronger ribs on 

later stages of growth, second, long sweeping growth 

lines that extend obliquely forward from the ribs to 

the edge of the venter, and third a series of small 

oblique folds that ornament the venter. Only the edge 

of the venter can be seen but presumably it is weakly 

carinated. The significance of the features exhibited 

by this mold is determined by comparing them with the 

features of the shells from Owl Creek, Miss. It appears from this comparison that the mold belongs to 

Morton's species, Baculites carinatus.

The Owl Creek shells show that in later stages 

the ribs become strongly developed on the flanks. An 

early stage in which the ribs are weak and a later stage 

in which they become strong are shown in the illustrations. There is much individual variation in the 

stage of growth at which the ribs make their first appearance on the flanks, some shells remaining smooth 

until a much later stage than do others. In cross section the shell is broadly subovate, the dorsum being 

slightly flattened and the venter weakly carinated. The 

trend of the growth lines and ribs on the flanks is 

strongly concave toward the aperture, those nearest 

the venter being strongly oblique and extending far 

forward.

The maximum dorsoventral diameter of the shell 

shown in plate 24, figure 5, is 24 mm, and the corresponding transverse diameter 19 mm. This incomplete 

shell is about 109 mm long and includes about 60 mm of 

the length of the living chamber.

Types.—The type of Baculites carinatus Morton is listed as 

present in the collection of the Academy of Natural Sciences 

of Philadelphia. One plesiotype from the Owl Creek formation 

at Owl Creek, Tippah County, Miss., USGS 707, USNM 128215; 

plesiotype from the same formation on Braddock's farm, Walnut 

Creek, 7 miles northeast of Ripley, Tippah County, Miss., USGS 

713, USNM 128216. Plesiotype from the Owl Creek formation 

in southeastern Missouri, USGS 16452, USNM 128214.

Range.—Owl Creek formation of Mississippi and Missouri.

Family SCAPHITIDAE

Genus DISCOSCAPHITES Meek, 1870

Discoscaphites iris (Conrad)

Plate 23, figures 23-30

1858. ScapMtes iris Conrad, Acad. Nat. Sci. Phila. Jour., 2d 

ser., v. 3, p. 335, pi. 35, fig. 23.

1892. ScapJiites iris Conrad. Whitfield, U. S. Geol. Survey Mon. 

18, p. 265, pi. 44, figs. 4-7. (Also issued as N. J. Geol. 

Survey, Paleontology ser., v. 1.)

?1926. ScapMtes conradi Morton (var.). Stephenson, Ala. Geol. 

Survey Spec. Kept. 14, p. 248, pi. 91, fig. 11. (Illustration only.)
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 135

The Owl Creek formation of southeastern Missouri 

has yielded 30 or more internal and external molds that 

are identified as belonging to Discoscaphites iris (Conrad), (USGS 19090) ; none of the specimens are entirely complete, the collection including poorly preserved parts of individuals representing young, medium 

and adult stages of growth. The larger internal molds 

show the characteristic form and ornamentation of 

Conrad's species. Internal molds of two juvenile 

shells are present in another collection (USGS 16430). 

Collections in the United States National Museum include 40 or more topotypes from Owl Creek, Tippah 

County, Miss. (USGS 594 and TOT), many of which 

are in a fair to good state of preservation.

Shell of medium size, closely coiled in early stages of 

growth, more loosely coiled in later stages; there is 

considerable individual variation in form and in the 

development and spacing of the nodes. Umbilicus 

small with steep sides. The living chamber expands 

rapidly, straightens out a little and becomes somewhat 

elongated, and in the gerontic stage bends inward and 

becomes noticeably constricted. In its earlier stages 

the shell is ornamented with numerous weak radiating 

ribs, some of which do not extend inward as far as the 

umbilical shoulder; in adults these ribs die out somewhat back of the inner end of the living chamber. In 

early stages the ribs are short, relatively stout, and cross 

the flank directly; in later stages their trend is obliquely 

toward the front.

The shells are typically ornamented with four rows 

of nodes on each flank. The outer row on the ventral 

angle has the most numerous and closely spaced nodes; 

the following rows inward have successively fewer and 

more-widely spaced nodes; on one medium-sized shell 

there are 32 nodes in the outer row, 26 in the second row 

inward, IT in the third, and 8 in the inner row. The 

nodes on the early stages of the shell are quite small; 

they become gradually larger in the forward direction, 

and are relatively coarse on the first half of the living 

chamber; toward the aperture they become smaller 

again.

The septate part of nearly every available specimen 

was not filled with matrix before burial and subsequently was mechanically crushed, making it difficult to 

determine in detail the complete pattern of the sutures; 

the sutures on the flank of a crushed topotype are shown 

on plate 23, figure 2T. The septa on the interior of one 

topotype are shown in plate 23, figure 28. Apparently 

the sutures as far as they can be seen conform closely 

to the sutures of Discoscaphites conradi (Morton), the 

type of the genus. The aperture is subquadrate in outline, with the lateral margins converging slightly outward.

Dimensions of the medium-sized topotype shown in 

plate 23, figures 23-25: Maximum diameter 41 mm, minimum diameter of the ultimate coil 28 mm, maximum 

radius center to venter 24 mm, dorsoventral diameter of 

the slightly constricted aperture 13 mm, maximum 

transverse diameter of the aperture 12 mm. The most 

inflated part of the shell at right angles to the plain of 

coiling is near the midlength of the living chamber; 

here the transverse diameter of the measured topotype 

is 16 mm.

Types.—The specimen (holotype) figured by Conrad is listed 

by Johnson (1905, p. 27) as present in the collection of the 

Academy of Natural Sciences, Philadelphia; three figured topotypes from Owl Creek, Tippah County, Miss., USGS 707, USNM 

128218. One plesiotype from the Owl Creek formation of southeastern Missouri, USGS 19090, USNM 128217.

Range.—Owl Creek formation of Mississippi and Missouri; 

Prairie Bluff chalk of Alabama. (Maestrichtian.)

Discoscaphites ,sp. 

Plate 23, figures 20-22

An internal mold representing part of the living chamber of an undescribed species of Discoscaphites Meek 

is present in one of the collections from the Owl Creek 

formation of southeastern Missouri (USGS 16429). 

The mold indicates a plumply rounded, closely coiled 

shell ornamented with numerous closely spaced, slightly 

sigmoid, radiating ribs and 4 rows of nodes. On this 

mold 10 ribs cross the venter where, however, they are 

much weaker than on the flanks. Eight of the ribs extend inward to the umbilical shoulder, the 2 additions,! 

ribs on the venter having been added by the dichotomy 

of 2 ribs on the flank. One row of small, weak nodes is 

present on each ventral angle, where each rib has a node 

on its crest; on each flank 3 to 4 millimeters inward from 

the ventral angle is a second row of weak nodes, 1 node 

on each rib. The maximum diameter of the mold as 

preserved is about 25 mm, the maximum radius center 

to venter about 16 mm; the estimated maximum dorsoventral diameter is 18 mm and the maximum transverse 

diameter 20 mm. USNM 128219.

The ribbing on this mold from Missouri matches 

rather closely that on a fragment of an undescribed 

species of Discoscaphites from Owl Creek, Tippah 

County, Miss. (USGS TOT, USNM 20861), and the two 

appear to belong to the same species.

Family ENGONOCERATIDAE

Genus SPHENODISCTJS Meek, 1871

Sphenodiscus pleurisepta (Conrad)

Plate 24, figures 1-4

1857. Ammonites pleurisepta Conrad, United States and Mexican Boundary Survey Kept., v. 1, pt. 2, p. 159, pi. 15, 

figs. la-c.

(For synonymy through 1941 see Tex. Univ. Pub. 4101, 

1941, p. 436.)
136 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Add:

1940. Sphenodiscus aff. P. pleurisepta Conrad. Stephenson and

Monroe, Miss. State Geol. Survey Bull. 40, p. 286, pi. 13,

fig. 6. (Illustration only.)

The only available specimen of this species from the 

Owl Creek formation of southeastern Missouri is a 

fragment of the internal mold of the septate part of a 

large individual (USGS 19088). Nineteen incomplete 

internal molds with shell substance adhering to parts 

of their surfaces, are present in one collection from the 

Owl Creek formation on Owl Creek, Tippah County, 

Miss. (USGS TOT). All of these have suffered mechanical compression and appear thinner than their 

true original form. The shell substance where preserved is brightly iridescent and in reflected light exhibits a play of greenish, pinkish, and bronzy tints. 

The well-preserved growth lines on some of the shells 

are broadly sigmoid in trend and indicate the presence 

on each flank at the margin of the aperture of a broad 

lateral crest centering a little outside the inner row of 

nodes, and a broad lateral sinus centering on the outer 

row of nodes; the growth lines also indicate the presence of a short ventral crest.

The one large fragment of an internal mold from 

Missouri is not mechanically compressed, as are the 

shells from Owl Creek, Miss.; its maximum transverse 

thickness about midway of the flanks is 42 mm; its 

venter is sharply rounded and it shows the sutures well 

preserved. The ventral lobe is broad and shallow and 

the ventral saddle is low, broad, and finely notched on 

its front edge. The first 5 saddles inward from the 

venter are divided; they increase in size to the 3d saddle 

and decrease from the 4th inward; as preserved the 

last 3 saddles inward from the venter are simple; the 

inner saddles are simple and number 7 or more.

The evidence for the reference of the Missouri specimen to /Sphenodiscus pleurisepta (Conrad) is the presence on the flanks of low undulations at positions corresponding to the positions of the nodes on earlier 

stages of growth of the species.

Types.—The holotype of this species is recorded as having 

come from "Jacun, 3 miles below Laredo"; since no Cretaceous 

rocks are exposed in that area the stated locality is obviously 

an error, unless the specimen was transported there by human 

or other mechanical agency. There is reasonable certainty 

that the holotype (USNM 9888) came from the Escondido 

formation (Maestrichtian) somewhere in the Rio Grande region 

of Texas, probably Maverick County. Plesiotype from the Owl 

Creek formation, Owl Creek, Tippah County,, Miss. (USGS 

707, USNM 128183) ; plesiotype from the Owl Creek formation 

of southeastern Missouri, collected and donated to the U. S. 

Geological Survey by Edison Shrum of Advance, Mo., through

Willard Farrar of the Missouri Survey. (USGS 19088, USNM 

128220.)

Range.—Owl Creek formation of Mississippi and Missouri; 

Corsicana marl, Kemp clay, and Escondido formation, of the 

Navarro group of Texas; Escondido formation of Mexico; all 

of Maestrichtian age.

LITERATURE CITED

Call, R. E., 1891, The geology of Crowleys Ridge: Ark. Geol. 

Survey 1889, v. 2, p. 1-223 (esp. p. 128, 129).

Conant, L. C., and McCutcheon, T. E., 1941, Tippah County 

mineral resources: Miss. State Geol. Survey Bull. 42, 

288 p., geol. map, pi. 1.

Conrad, T. A., 1858, Observations on a group of Cretaceous fossil shells found in Tippah County, Miss., with descriptions 

of fifty-six new species: Acad. Nat. Sci. Phila. Jour., 2d 

ser., v. 3, p. 323-336, pis. 34, 35.

———— 1860. Description of new species of Cretaceous and 

Eocene fossils of Mississippi and Alabama: Acad. Nat. Sci. 

Phila. Jour., 2d ser., v. 4, p. 275-298, pis. 46, 47.

1865, Observations on American fossils with descriptions

of two new species: Acad. Nat. Sci. Phila. Proc., v. 17, p. 184.

———— 1870, Notes on Recent and fossil shells, with descriptions of new species, Am. Jour. Conchology, v. 6, pt. 1, 

p. 71-78.

Crider, A. F., 1906, Geology and mineral resources of Mississippi : U. S. Geol. Survey Bull. 283,. 99 p., 4 pis.

Dall, W. H., 1890-1903, Contributions to the Tertiary fauna of 

Florida . . .: Wagner Free Inst. Sci. Trans., v. 3, pts. 1-6, 

1654 p., 60 pis.

Farrar, Willard, 1935, The Cretaceous and Tertiary geology [of 

southeast Missouri]: Mo. Geol. Survey and Water Resources Bien. Rept. 58th Gen. Assembly, app. 1, pt. 1, 

p. 1-35.

Farrar, Willard, and McManamy, Lyle, 193T, The geology of 

Stoddard County, Missouri: Mo. Geol. Survey and Water 

Res. Bien. Rept. 59th Gen. Assembly, app. 6, 92 p., geol. map.

Gabb, W. M., 1860, Description of some new species of American 

Tertiary and Cretaceous fossils: Acad. Nat. Sci. Phila. 

Jour., 2d ser., v. 4, p. 375-406, pis. 67-69.

———— 1861, Synopsis of the Mollusca of the Cretaceous formation: Am. Philos. Soc. Proc., v. 8, p. 57-257 (reprint of 

same date, p. 1-201).

Gardner, J. A., 1916, Mollusca, Brachiopoda, and Vermes, in 

Clark, W. B., and others, Systematic paleontology, Upper 

Cretaceous deposits of Maryland, Md. Geol. Survey, Upper 

Cretaceous [Maryland], p. 371-733, pis. 12-45.

Glenn, L. C., 1906, Underground waters of Tennessee and Kentucky west of Tennessee River and of an adjacent area in 

Illinois: U. S. Geol. Survey Water-Supply Paper 164, 173 p., 

7 pis.

Harbison, Anne, 1945, Upper Cretaceous mollusks of the lower 

Ripley formation near Dumas, Mississippi: Acad. Nat. Sci. 

Phila. Proc., v. 97, p. 75-92, pis. 1-6.

Hilgard, B. W., 1860, Report of the geology and agriculture of 

the State of Mississippi: 391 p., geol. map, Jackson, Miss., 

E. Barksdale, State Printer.

Johnson C. W., 1905, Annotated list of the types of invertebrate 

Cretaceous fossils in the collection of the Academy of Natural Sciences of Philadelphia: Acad. Nat. Sci. Phila. Proc., 

v. 57, 28 p.
OWL CREEK FOSSILS FROM CROWLEYS RIDGE, SOUTHEASTERN MISSOURI 137

Lamar, J. E., and Sutton, A. H., 1930, Cretaceous and Tertiary

sediments of Kentucky, Illinois, and Missouri: Am. Assoc.

Petroleum Geologists Bull., v. 14, no. 7, p. 845-866, 4 figs. 

Marbut, C. F., 1902, The evolution of the northern part of the

lowlands of southeastern Missouri: Mo. Univ. Studies, v. 1,

no. 3, p. 145-207 (reprint p. 1-63). 

Matthes, F. E., 1933, Cretaceous sediments in Crowleys Ridge,

southeastern Missouri: Am. Assoc. Petroleum Geologists

Bull., v. 17, no. 8, p. 1003-1009.

——— 1933, The Pleistocene diversion of the Mississippi River 

across Crowley's Ridge, southeastern Missouri [abstracts]: 

Science, new ser., v. 77, p. 459-460; Washington Acad. Sci. 

Jour., v. 23, no. 12, p. 572-573

———— 1934, Pleistocene diversions of the Mississippi and the

Ohio Rivers near Crowleys Ridge [abstract]: Geol. Soc. 

America Proc., 1933, p. 96-97.

Meek, F. B., 1864, Check list of the invertebrate fossils of North. 

America, Cretaceous and Jurassic: Smithsonian Misc. Coll. 

7, no. 177, 40 p.

Moore, H. B., 1939, Faecal pellets in relation to marine deposits, 

in Trask, P. D., ed., Recent marine sediments, Am. Assoc. 

Petroleum Geologists, p. 516-524.

Morton, S. G., 1829, Description of the fossil shells which characterize the Atlantic Secondary formation of New Jersey 

and Delaware; including four new species: Acad. Nat. Sci. 

Phila. Jour., 1st ser., v. 6, p. 72-100, pis. 3-6.

——— 1834, Synopsis of the organic remains of the Cretaceous 

group of the United States: 88 p., 19 pis., Phila., Key and 

Biddle.

Ross, C. S., and Stephenson, L. W., 1939, Calcareous shells replaced by beidellite: Am. Mineralogist, v. 24, p. 393-397, 

fig. 1.

Stephenson, L. W., 1923, The Cretaceous formations of North 

Carolina: Pt. 1, Invertebrate fossils of the Upper Cretaceous 

formations: N. C. Geol. and Econ. Survey, v. 5, 592 p., 100 

pis.

— 1939, Fossil mollusks preserved as clay replacements, 

near Pontotoc, Miss.: Jour. Paleontology, v. 13, no. 1, 

p. 96-99, pi. 16.

— 1941, The larger invertebrate fossils of the Navarro 

group of Texas . . .: Tex. Univ. Pub. 4101, 641 p., 95 pis.

— 1952 [1953], Larger invertebrate fossils of the Woodbine

formation (Cenomanian) of Texas: U. S. Geol. Survey Prof. 

Paper 242, 226 p., 59 pis.

Stephenson, L. W., and Crider, A. F., 1916, Geology and ground 

waters of northeastern Arkansas: U. S. Geol. Survey WaterSupply Paper 399, 315 p., (esp. p. 129-132).

Stephenson, L. W., and Monroe, W. H., 1937, Prairie Bluff chalk 

and Owl Creek formation of eastern Gulf region: Am. Assoc. Petroleum Geologists Bull., v. 21, no. 6, p. 806-809.

——— 1938, Stratigraphy of Upper Cretaceous series in Mississippi and Alabama: Am. Assoc. Petroleum Geologists Bull., 

v. 22, no. 12, p. 1639-1657.

——— 1940, Upper Cretaceous deposits [Mississippi]: Miss.

State Geol. Survey Bull. 40, 296 p., 15 pis. 

Stewart, R. B., 1930, Gabb's California Cretaceous and Tertiary

type lamellibranchs: Acad. Nat. Sci. Phila. Spec. Pub. no. 3,

314 p., 17 pis. 

Tuomey, Michael, 1854, Description of some new fossils, from

the Cretaceous rocks of the southern States: Acad. Nat.

Sci. Phila. Proc., v. 7, p. 167-172. (Descriptions brief and

inadequate, locality descriptions inadequate, no illustrations, and types lost) 

Wade, Bruce, 1926, The fauna of the Ripley formation on Coon

Creek, Tenn.: U. S. Geol. Survey Prof. Paper 137, 272 p., 72

pis. 

Weller, Stuart, 1907, A report on the Cretaceous paleontology of

New Jersey: N. J. Geol. Survey, Paleontology series, v. 4,

871 p., Ill pis. (bound separately). 

Whitfield, R. P., 1885, Brachiopoda and Lamellibranchiata of the

Raritan clays and greensand marls of New Jersey: U. S.

Geol. Survey Mon. 9, 338 p., 35 pis.

INDEX

Page

(Acantkocardia) tippanum, Cardium...__-_... 118 

Acteon linteus.. _..._..._....__....... 133

acutilineata, Ctenoides.______________ 113 

Lima.--.-..................... 104, 113, 114; pi. 17

acutilineata texana,Lima.__....... .____... 114

Advance Lowland_________._..___. 100 

alabamense, Cardium (Granocardium)... ..._.. 119

alabamensis, Idonearca..______._._._ 109

atta, Cyprimeria—...__.______ 105, ISO; pl. 20

alveata, Gyrodes________________.. 125

Natica (Gyrodes).................. __...__ 125

americana, Gastrochaena....____.._._._ 124

Ammonites pkurisepia..-._..__.......__.. 135

Anatimya anteradiata.-................ 104, 116; pl. 17

longula......——.__.___....____. 116

texana..... .———.....................__ 116

sp_ ——————————- 104,1/6; pi. 17

(Anatimya) avteradiata, Pkoladomya............ 116

Anatina............................______ 115

anatinus, Solen.-....___________. 115

Anckuraspp—...—..............._ 105,188; pl. 88

angulicostata, Trigonia................. 104,118; pl. 16

anteradiata, Anatimya___. ______ 104, 116; pi. 17 

Pholadomya (Anatimya)-...._______ 116

anteradiata texana, Anatimya........ ........... 114

Aphrodina tippana.................._ 105,110; pl. SO

Area (Macrodon) eujalensis.-- _________ 108 

Ardeola, stratigraphic section near.. ______ 100 

argentea, Tenuipteria................... 104, 111; pi. 16

argenteus, Inoceramus.............______ 110,111

argiUensis, Pecten.......———————......... 113

Axinaea rotundata..._______________ 108

B

Bacuhtescarinatus-—.................. 105, 134; pi. 84

spillmani..................__......___ 134

tippaensis-- —————————————___. 134 

bexarensis, Crassatella vadosa.....___..__ 117 

biplieata, filiquaria.-.................. ......... 123

Solen (Leptosokn)..........___.....__ 123

biplicatus, Leptosoler.................... 105, 183; pl. 20

Breviarca sp...—————————.——.—__ 104, 109 

Brevicardium fragile.................— 105, 120; pi. 18

bvboana, Tettina...—........___ 105, 181, 122; pi. SO

buboanus, Trobus.................. 105, 187, 128; pi. 88

bubonis, Pecten (Camptonectes)......... 104,113; pl. 17

Bullopsis cretacea....................... 105, 133; pi. 83

Call, R. E., quoted.....__......_.__...... 99

(Camptonectes) bubonis, Pecten................ 104,113

hUgardi, Pecten......................... __ 104, US

eapax, Cucullaea................................ 109

Idonearca...................... 104, 109, 110; pi. 16

Cardium protextum............................. 116

Cardium (Acanthocardia) tippanum__..___ 118

Cardium (Granocardium) alabamense______ 119

lowei—........................ 105,119; pi. 19

tippanum—................... 105,118; pi. 19

Cardium (Laevicardium) spiUmanir ............. 120

Cardivm (Pachycardium) spillmani..... 105, ISO; pi. 80

stantoni................................. 120

carinatus, Baculites.................... 105,134; pi. 84

[Italic numbers indicate descriptions]

Page 

Caveola producta...........—————— ————. 132

sp———————————— 105, lS8;pl. 83

chatfleldensis, Crassatella vadosa..............— 117

Clayton formation.._____._...-----. 98,99,101,102

Cliona microtuberum.-* _______— 104, 106; pi. 15 

conradi, Discoscaphites. .....——————————— 135

Pholadomya.--..-.......—————————— 115

Scaphites.-- ———.—————————————— 135 

Veniella. ......................... 105, 117; pi. 18

Coon Creek tongue of Ripley formation.... __ 117,

118,122,124,125,126,130,133 

Cor&wZaspp-------—_-—.„.—————— 105,183

Corsicana marl——......— 106,113,114,118,120,136

costata, Exogyra............................ 111; pi. 15

costellatus, Inoceramus.--—..................... 111

Crassatella gardnerae....... ....————————— 117

vadosa--......... ._._____...-———... 117,118

————.———— 117

.........————..— 117

manorensis-............................ 117

ripleyana..—................. 105, 117; pi. 19

wadei—. ..................... ————— 117

CrassaMlites ripleyanus.—————————————— 117

vadosus. ————————————————————— 117

CreneJla elegantula.. —————————— — — 114,115

microstriata-——................ 104,114,115; pi. 17

serica—........................... 104, JIfcpl. 17

Crenella (Stalagimum) serica-—————————— 114 

cretacea, Bullopsis- ................... 105,1SS; pi. 8S

Crowleys Ridge, description,.———.————— 99,100 

Ctenoides acutilineata-......._———————— 113

Cucullaea capax...........................—— 109

tippana....——————————————————— 109

vulgaris—..........................—...... 109

Cucullaea (Idonearca) tippana................... 109

Cuneolustippanus..................... 104, lit; pi. 17

Cyclichna sp______________——__ 105,134 

Cyprimeria aUa....—__..——.—.. 105, ISO; pi. 80

major..————————.———————————— 120 

torta........................................ 120

densata, Dosinia....—............—......—... 120

Discoscaphites conradi..................—.—— 135

iris................................ 105, lS4;pl. 83

sp..-. — -—--—---.-.-...--—-——- l$6;pl.83 

Distribution of fossils.......—.—.———. 104-105

Donaxfordii-..-.........................._— 107

Dosinia densata.-..-............................ 120

Dreissena tippana.....________—..._.. 115

Drilluta ripleyana—.........——————————— 131

sp. ________. _________ 105,131; pi. 88

E

eborea, Tellinimera________————__.. 122 

elegantula, Crenella-.......................... 114,115

ellipticum, Legumen................... 105, 181; pi. 80

Eoacteon.-..............____———..——— 138

linteus—............... ......... - 105, 183,'pl. 83

Eoharpa sinuosa.__________ 105,131, 138; pi. S3 

Erd, R. C., quoted_______________ 101,102 

Escondido formation......—————————— 113,136

eujalensis, Area (Macrodon)..................... 108

Nemodon.......................... 104, 108; pi. 15

Trioonia........................... 104, HS;pL 16

Page

(Euspira) halli, Polinices_______..____ 125

Exogyra costata-.. ———..____-._———._ 104,

106, 111, 113, 117,118,120, 121,123,126; pi. 16

ponderosa-— 106,107, 111, 113,114,117.118,120,126

Farrar, Willard, cited.._.____._...__—_-_.. 99,100

Fictoacteon..._____________.._____ 132 

Ficus octoliratus.------.-.___---------___ 128

Jordii, Donax._.-___-_______--___ 107 

Jornosa, Helicaulax-.-.____.___ 105, 188; pi. 81 

fragile, Brevicardium. ___ _ ___. _ 105, 180; pi. 18 

Fusinus, sp. A...____________ 105, ISO; pi. 88 

sp. B—........................... 105, ISO; pi. 88

G 

Gardner, Julia, cited...._____________ 99

gardnerae, Crassatella.-....--..——————--.. 117

Gastrochaena americana. ____________. 124

ripleyana. ______________ 105, 184; pi. 81

Glycymeris rotundata— ______—— 104, 108; pi. 16

Goniochasma_————___———————.__ 184

scaphoides.--...---. ____________ 124

sp—.———.——————— 105, 184; pl- HI

(Granocardium) alabamense, Cardium-.-........ 119

lowei, Cardium.-. _________ 105, 119;pl. 19 

tippanum, Cardium....__..—— 105, 118; pl. 19

"Green marl"..———.———..——————__ 134 

Gyrodes alveata.................................. 125

major—..................................... 125

petrosus.................................... 125

spzHmanii.-....................... 105, 186; pl. 81

supraplicatus...................... 105, 185; pl. 81

sp..........-.-....................... 186; pl. SI

(Gyrodes) alveata, Natica........................ 125

halli, Polinices (Evspira)________....__ 125

Hamulus sguamosus................... 104, 108; pl. 16

Helicaulax formosa..................... 105, 188; pl. 81

hilgardi, Pecten................................. 113

Pecten (Camptonectes)...—....... 104, llS;pl. 17

Homerstown marl——.——————————.... 134

Idonearca alabamensis........___._—__ 109

capax.......................... 104,100,110; pl. 15

saffordi..................................... 98

tippana..................................... 109

(Idonearca) tippana, Cucullaea.................. 109

Inoceramus argenteus.. ___..„————_ 110,111 

costellatus................................... Ill

iris, Discoscaphites... __________ 105, 134; pl. 8$ 

Scaphites_————.———————————— 135

jugosa, Voluta.. __..__...————————— 130

K

Kemp clay...———————— 106,113,117,129,136

L

(Laevicardium) spttlmani, Cardium.............. 120

Lamar, J. E., and Button, A. H., quoted—.— 98

139
140 INDEX

Page 

lagueata, Pinna....................—. 104, 110; pi. 16

Leda longifrons................................. 107

slackiana....................... ___——- 107

Legurnen ellipticum.................... 105, Itl; pi. 80

Leptosolen biplicatus... _________ 105, 123; pi. 20 

(Leptosolen) biplicata, Solen___________ 123 

Lima acutUineota................... 101,113, 114; pi. 17

texana................................. 114

Linearia........................................ 188

metastriata......................... 105,122; pi. SO

linteus, acteon.................................. 133

Eoacteon........................... 105, 199; pi. 88

Solidulus................................. 132,133

Liopeplurn rugosum-.............. 105, 130, 131; pi. ti

subjugosum-.............................. 130,131

Ltopisthaprotexta..--.................. 104,118; pi. 19

List of collection numbers......——___—— 104

longifrons, Leda-............................... 107

Nuculana.......................... 104, 107; pi. 16

longula, Anatimya...............______—— llrt

lowei, Cardium (Granocardium) . ____ 105,119; pi. 19 

(Lunatia) rectilabrum, Natica................... 125

M

McManamy, Lyle, cited...________._ 99 

McNairy sand........................ 99,100,102,105

(Macrodon) eufalensis. Area..................... 108

major, Cyprimeria.........................;—. 120

Gyrodes—.................................. 125

manorensis, Crassatella vadosa................... 117

Marbut, C. F., cited...____________ 99,100 

Marshalltown formation—__———___—— 114 

marylandica, Morea............................. 129

Matawan formation......___......___—— 110

Matthes, F. E., cited.................._..._ 98

Merchantville clay...._____——____.... 110

Meretrix tippana................................ 120

metastriata, Linearia................... 105, 122; pi. SO

microstriata, Crenella.............. 104,114,115; pi. 17

microtuberum, Cliona................... 104, 106; pi. 15

Midway group._____.___—_____.. 98,102 

Mississippi River, diversion of_-_______ 99.100 

Monmouth formation. ______ 109,114,117,124,133 

monmouthensis, Panope................ 105,123; pi. 21

Morea marylandica---..-.—.................... 129

transenna.......................... 105, 129; pi. 22

Mysia parilis................................... 121

N

Nacatoch sand. _________________ 117 

Napulus octoliratus................. 105, 128, 129; pi. 21

sp..................................... 129; pi. 91

Natica (Gyrodes) alveata.._____________ 125 

Natica (Lunatia) rectilabrum.................... 125

Navarro group -....—... 113,117,120,124,129,132,136

Nemodon eufaulensis................... 104, 108; pi. 15

Nucula percrassa................... 104, 106, 107; pi. IS

Nuculana longifrons...............__ 104,107; pi. IS

sp.......................................... 107

Occidentalis, Pholadomya........................ 115

octoliratus, Ficus................................ 128

Napulus.......................105,188, 129; pi. 21

Olmstead Ferry landing, 111., stratigraphic section......._____..___...... 98

Ostrea tectkosta......................... 104, 111; pi. 18

Owl Creek formation, description of, Mississippi-.............................. 97

southeastern Missouri____________ 100 

Tennessee__________________ 97

Page 

(Pachycardium) spittmani, Cardium.... 105,120; pi. 20

(Pachycardium) stantoni, Cardium.............. 120

Pandoracea..___..——.—————————— 115 

Panope monmouthensis................. 105,123; pi. tl

parilis, Mysia................................... 121

Tenea—........................... 105, 121; pi. 20

pateriformis, Pseudomalaxis............ 105,124; pi. 21

Pecten.......................................... US

argittensis................................... 113

hilgardi.. .........__...................... 113

simplicius......... ..........^.............. 113

Pecten (Camptonectes) bubonis.......... 104,113; pi. 17

hdgardL........................... 104, US; pi. 17

Pecten (Syncyclonema) simplicius....... 104,113tfpl. 17

Peedee formation_——__..———————— 113 

percrassa, Nucula.................. 104,105,107; pi. 15

perplana, Scarnbula.................... 105,118; pi. 18

petrosus, Gyrodes................................ 125

Pholadomya conradi—.......................... 115

occidentalis.................................. 115

tippana............................ 104, 115; pi. .78

Pholadomya (Anatimya) anteradiata............. 116

pilsbryi, Pseudomalixis........................ 124,125

Pinna lagueata......................... 104,110; pi. 16

planicosta, Venericardia......................... 98

pleurisepta, Ammonites......................... 135

Sphenodiscus............... 102,105, 135, 136; pi. 24

Polinices rectilabrum-.................. 105,125; pi. 21

Polinices (Euspira) hatti........................ 125

ponderosa, Exogyra.... 106,107, 111, 113,114,117,118,120

Porters Creek clay......._.__———__—— 98,102

Prairie Bluff chalk...._.................... 129,135

producta, Caveola............................... 132

protexta, Liopistha...___________ 104./l6,-pl. 19 

protextum, Cardium...—....................... 116

Providence sand_________—..___- 115,116 

Pseudomalaxis pateriformis.-........... 105, 124; pi. 21

pilsbryi................................... 124,125

ripleyana................................... 125

R

rectilabrum, Natica (Lunatia)................— 125

Polinices........................... 105,126; pi. 21

Red Bank sand__________.._____— 114 

Ripley formation......105,107,108,113,116,117,128,131

ripleyana, Crassatella vadosa............ 105, 117; pi. 19

Drittuta.................................... 131

Gastrochaena....................... 105, 184; pi. tl

Pseudomalixis..--------.................... 125

ripleyanus, CrassateUites........................ 117

rotundata, Axinea............................... 108

Glycymeris.-....................... 104,108; pi. 15

rugosum, Liopeplum............... 105,780,131; pi. tt

saffordi, Idonearca............................... 98

acabra, Trigonia................................. 112

Scambula perplana..................... 105,118; pi. 18

Scaphites conradi................................ 135

irit......................................... 135

scaphoides, Goniochasma........................ 124

serica, Crenella......................... 104,114; pi. 17

serica, Crenetta (Stalagmium)....—————.— 114

Serpula sp_____________._.___... 106 

SUiquaria biplicata.............................. 123

simplicius, Pecten............................... 113

Pecten (Syncyclonema)-......——— 104,113; pi. 17

sinuosa, Eoharpo................... 105,131, 1S2; pi. 2S

slackiana, Leda................................. 107

Solen anatinus.................................. 115

Solena (Leptosolen) biplicata-.-..--------..-.— 123

Page 

Solidulus linteus.............................. 132,133

Sphenodiscus pleurisepta....... 102,105, 1S5, 136; pi. 24

spillmani, Baculites............................ 134

Cardium (Laevicardium).................... 120

Cardium (Pachycardium)........... 105, 120; pi. 20

spillmanii, Gyrodes..................... 105,185; pi. 81

squamosus, Hamulus................... 104, 106; pi. 15

(Stalagmium) serica, Crenella.................'._ 114

stantoni, Cardium (Pachycardium).............. 120

stimpsoni, Xylophaga........................... 124

Stratigraphic sections_..___.____ 98,100,101 

subjugosum, Liopeplum....................... 130,131

supraplicatus, Gyrodes................... 105, 126; pi. 81

(Syncyclonema) simplicius, Pecten—........... 104,113

tectkosta, Ostrea......__________ 104, 111; pi. 16

Tellina buboana.................... 105, 121,122; pi. 20

Tellinimera eborea.............................. 122

Tenea parilis........................... 105,121; pi. 20

Tenuipteria...........—........................ 110

argentea............................ 104, 111; pi. 16

texana, Anatimya anteradiata.............___ 116

Lima acutilineata.......................... 114

tippana, Aphrodina.................... 105,120; pi. #0

Cucuttaea................................... 109

Cucullaea (Idonearca)....................... 109

Dreissena................................... 115

Idonearca................................... 109

Meretrix.................................... 120

Pholadomya........................ 104,116; pi. 18

Turrttella.......................... 105,126; pi. 22

tippaensis, Baculites............................ 134

tippanum, Cardium (Acanthocardia)............ 118

Cardium (Granocardium)........... 105,118; pi. 19

tippanus, Cunedus..................... 104,116; pi. 17

torta, Cyprimeria................................ 120

transenna, Morea....................... 105, 129; pi. tt

Trigonia angulicostata.................. 104,112; pi. 16

enfaulensis......................... 104,112; pi. 18

scabra...................................... 112

Trobus......................................... m

buboanus....................... 105, 187, 128; pi. 22

Turrttella tippana...................... 105, 126; pi. 22

vertebroides..................... 105, £86,127; pi. ti

sp__.__.._..______.....____ 98,108

vadosa, Crassatella--..———__—..___ 117,118 

vadosa bexarensis, CrassateUa.................... 117

chatftelderisis, Crassatella.................... 117

manorensis, Crassatella...................... 117

ripleyana, CrassateUa............... 105,117; pi. 19

wadei, Crassatella........................... 117

vadosus, CrassateUites.............—............ 117

Venericardia planicosta—....................... 98

sp.

Venietta conradi........................ 105,117; pi. 18

vertebroides, Turritetta...—.;...... 105, 128, 127; pi. ti

Valuta jugosa........—......................... 130

Volutomorpha spp___...___———105, 1S1; pi. 88 

ris, Cucullaea............................. 109

W

wadei, Craasaatetta vadosa....................... 117

Wenonah sand.___..—.—————————— 117

Woodbury clay.—...———.——-——————— 110

Xylophaga stimpsoni................—........— 124

o
PLATES 14-24

347625—55-

GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 14

A. LN COM FORM ABLE CONTACT BETWEEN PLANT-BEARING CLAY OF McNAIRY AND

OVERLYING OWL CREEK FORMATIONS.

Hand of D. R. Stewart at left (Lyle McMaiiamy at right) marks contact. In road cut on southeastfacing slope of Crow-leys Ridge, 0.35 mile northwest of 4rdeola station, Stoddard County, Mo.

B. UNCONFORMABLE CONTACT BETWEEIN OWL CREEK AND OVERLYING CLAYTON

FORMATIONS. 

Same locality as A. Head of hammer marks contact.

.*>

Iff.'.

C. PLANT-BEARING CLAY AT TO1' OF McNAIRY SAND, OVERLAIN IN SUCCESSION BY

OWL CREEK AND CLAYTON FORMATIONS.

Exposure in SEiNEJSEi sec. 26, T. 29 N.. R. 14 E.. Scott County, Mo. McManamy sits on 

Clay ton formation with feet on Clay ton-Owl Creek contact; Stewart stands at Owl Creek-McNairy contact.

D. NEAR VIEW OF OWL CREEK-PLANT-BEARING CLAY CONTACT. 

See preceding photograph (view C). Head of hammer marks contact.

VIEWS OF CLAYTON (PALEOCENE), OWL CREEK AND McNAIRY (UPPER CRETACEOUS), FORMATIONS IN STODDARD AND SCOTT COUNTIES, MO.

Photographs by H. S. McQueen.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 15

22 20 21 25 

CLI01\A, HAMLLLS, MCLLA, 1\EMODOX, GLICIMERIS, \LCLLAXA, AAD IDONEARCA
PLATE 15

[Figures natural size except as indicated]

FIGURES 1, 2. Cliona microtuberum Stephenson (p. 106).

Casts of borings, X 2, in a fragment of bivalve shell (1) and in a gastropod shell (2), from a dry branch 300 feet 

downstream from a road crossing, 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, 

USNM 128081. 

3. Hamulus squamosus Gabb (p. 106).

Rubber cast from external mold, X 2, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128083. 

4-7. Nucula percrassa Conrad (p. 106).

4, 5. Views of a nearly perfect topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128084.

6. Interior of the left valve of a topotype, from the same source. USNM 128084.

7. Internal mold, X 2, of part of a right valve, from ditch on north-south road 1.4 miles west by south of Ardeola

station, Stoddard County, Mo. USGS 19090, USNM 128085. 

8-12. Nemodon eufaulensis (Gabb), (p. 108).

8. Left valve, X 2, of a topotype, from Eufaula, Barbour County, Ala. USNM 18830.

9. 10. Right valve, X 2, of another topotype, and hinge, X 2, of the same, from Eufaula. USNM 18830.

11, 12. Internal mold, X 2, and rubber cast of external mold, X 3, of a left? valve, from ditch on north-south road

1.4 miles west by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128092. 

13-17. Glycymeris rotundata (Gabb), (p. 108).

13, 14. Views of a right valve, from Owl Creek, Tippah County, Miss. USGS 594, USNM 21681.

15. Interior of a juvenile left valve, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128093.

16. Internal mold of a right valve, from ditch on north-south road 1.4 miles west by south of Ardeola station, 

Stoddard County, Mo. USGS 19090, USNM 128095.

17. Internal mold of a juvenile left valve, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest

of Ardeola station, Stoddard County, Mo. USGS 16429, USNM 128094. 

18, 19. Nuculana longifrons (Conrad), (p. 107).

18. A left valve, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128088.

19. Internal mold, X 2, of a right valve, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128087. 

20-26. Idonearca capax (Conrad), (p. 109).

20. 21. Views of a medium-sized topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128097.

22. Rubber cast from the interior of an adult topotype, for comparison with figures 23, 24. USGS 707, USNM 

128097.

23. 24. Views of the internal mold of a left valve, from ditch on north-south road 1.4 miles west by south of Ardeola 

station, Stoddard County, Mo. USGS 19090, USNM 128098.

25. Internal mold, X 2, of a medium-sized left valve, with surface sculpture impressed upon it, from the preceding 

locality, USNM 128098.

26. Rubber cast, X 1%, from the external mold of the preceding specimen.
FIGURES 1-3. Trigonia angulicostata Gabb (p. 112).

1. Right valve, from Owl Creek, Tippah County, Miss. TJSGS 707, TJSNM 128110.

2. 3. Internal mold of right valve (2) with sculpture impressed upon it, and rubber cast from external mold of a left 

valve (3), from road on southeast facing slope of Crowleys Ridge 0.35 mile northwest of Ardeola station, 

Stoddard County, Mo. USGS 16429, TJSNM 128109. 

4-9. Tenuipteria argentea (Conrad), (p. 111).

4, 5. Two topotypes, a right valve (4) and hinge, X 2, of a left valve (5), from Owl Creek, Tippah County, Miss. 

USGS 707, USNM 128104.

6. Left valve from the Owl Creek locality. USGS 6464, USNM 128102.

7. Internal mold of left valve with weakly impressed sculpture, from ditch on north-south road 1.4 mile west by 

south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128103.

8. Incomplete internal mold, X lK> °f right valve, from a dry branch 300 feet downstream from a road crossing, 

2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128105.

9. Incomplete external mold of left valve, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest

of Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128106. 

10-12. Pinna laqueata Conrad (p. 110).

10. Left side of topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128100.

11. Left side of an incomplete topotype, from the same source. USNM 128099.

12. Rubber cast from incomplete external mold of right valve, from southeast-facing slope of Crowleys Ridge 0.35

mile northwest of Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128101. 

13, 14. Ostrea tecticosta Gabb (p. 111).

Internal molds of two left valves, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128107. 

15-17. Trigonia eufaulensis Gabb (p. 112).

15. A topotype, right valve, from bluff on Chattahoochee River at Eufaula, Barbour County, Ala. USGS 854, 

USNM 128112.

16. 17. Internal mold, X 1/4, of left valve and rubber cast, X 1J^, from incomplete external mold of right valve, 

from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard County, Mo. USGS 

19090, USNM 128111. 

18. Exogyra costata Say (p. 111).

Rubber cast from external mold, X 2, of a left valve from road on southeast-facing slope of Crowleys Ridge 0.35 

mile northwest of Ardeola station Stoddard County, Mo. USGS 16452, USNM 128108.
GEOLOGICAL RTTRVEY PROFESSIONAL PAPER 274 PLATE 16

15 18 12

TRIGONIA, TENLIPTERIA, PINNA, OSTREA, APsD EXOGYRA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 17

PECTEN, CREKELLA, CLNEOLUS, ANATIMVA, AND LIMA
PLATE 17

[Figures natural size except as indicated]

FIGURES 1-4. Pecten (Camptonectes) bubonis Stephenson (p. 113).

1, 2. Two topotypes, left and right valves, X 2, from Owl Creek, Tippah County, Miss. TJSGS 707, TJSNM 128113. 

3, 4. Rubber casts from two external molds of a left and a right valve, X 2, from ditch on north-south road 1.4 miles 

west by south of Ardeola station, Stoddard County, Mo. TJSGS 19090, USNM 128114.

5. Pecten (Camptonectes) hilgardi Stephenson? (p. 113).

Rubber cast from external mold, X 2, from a road ditch 150 feet south of a road junction about a mile northwest 

of Ardeola Station, Stoddard County, Mo. TJSGS 16430, TJSNM 128115.

6. Pecten (Syncyclonemaf) simplicius (Conrad), (p. 113).

Internal mold, X 2, from road in southeast-facing slope of Crowleys Ridge 0.35 mile northwest of Ardeola station,

Stoddard County, Mo. TJSGS 16452, TJSNM 128116. 

7-10. Crenella microstriata Stephenson, n. sp. (p. 114).

7, 8. The holotype, a right valve, X 3, and the same, X 6, from Owl Creek, Tippah County, Miss. TJSGS 707,

TJSNM 128123.

9, 10. Views of an internal mold, X 3, from a dry branch 300 feet downstream from a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, TJSNM 128126. 

11, 12. Crenella serica Conrad (p. 114).

A topotype, a left valve, X 3, and the same X 6, from bluff on Chattahoochee River at Eufaula, Barbour County,

Ala., TJSGS 854, USNM 128120. 

13, 14. Cuneolus tippanus (Conrad), (p. 115).

Right and left valves, X 1%, of neotype, from Owl Creek, Tippah County, Miss. TJSGS 6464, USNM 76499. 

15-17. Anatimya anteradiata (Conrad), (p. 116).

15, 16. Two topotypes, the internal mold of a right valve with sculpture impressed upon it, and the interior of

left valve, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128132. 

17. Internal mold, X 1%, of posterior part of a right valve, from ditch on north-south road 1.4 miles west by south

of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128131. 

18. Anatimya'! sp. (p. 116).

Incomplete external molds, X 1 l/z, of right and left valves of a shell from a dry branch 300 feet downstream from a

road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16461, USNM 128133. 

19-21. Lima acutilineata (Conrad), (p. 113).

19. A topotype, a right valve, X 3, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128117. (Also 

illustrated in N. C. Geol. and Econ. Survey v. 5, pi. 58, fig. 5, 1923, under old cat. no. 20665.)

20. Internal mold, X 1J4, of a left valve, from a dry branch 300 feet downstream from a road crossing 2.1 miles 

southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128118.

21. Rubber cast from internal mold, X 3, of a right valve, from southeast-facing slope of Crowleys Ridge 0.35 

mile northwest of Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128119.
PLATE 18

[Figures natural size except as Indicated]

FIGURES 1, 2. Veniella conradi (Morton), p. 117).

1. Right valve, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128138.

2. Incomplete internal mold of right valve, X 1J6, with concentric ridges impressed upon it, from ditch on northsouth road 1.4 miles west by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128137. 

3-5. Scambula perplana Conrad (p. 118).

Internal molds, X 2, of two right valves and one left valve, from the preceding locality. USGS 19090, USNM

128142. 

6, 7. Brevicardium fragile Stephenson (p. 120).

6. A topotype, X 5, a right valve, from Owl Creek, Tippah County, Miss. USGS 6464, USNM 128151.

7. Internal mold, X 5, of a right valve, from southeast-facing slope of Crowleys Ridge 0.35 mile northwest of

Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128152. 

8-13. Pholadomya tippana Conrad (p. 115).

8. 9. Views of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128128. 

10, 11. Views of another topotype in the same collection. USNM 128128.

12. An incomplete internal mold with sculpture impressed upon it, from Fullenwider farm 1 mile southeast of 

Oran, Scott County, Mo. USGS 16453, USNM 128130.

13. An incomplete internal mold with impressed sculpture, from road ditch in southeast-facing slope of Crowleys 

Ridge 0.35 mile northwest of Ardeola station, Stoddard County, Mo. USGS 16454, USNM 128129.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 18

11 13

VENIELLA, SCAMBULA, BREVICARDIUM, AND PHOLADOMTA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 19

X3 21 

CARDIUM, CRASSATELLA, AND LIOPISTHA

18 X 2
PLATE 19

[Figures natural size except as indicated]

FIGURES 1-8. Cardium (Granocardium) lowei Stephenson, n. sp. (p. 119).

I-4. Views, X 2, of a paratype, a left valve, (1, 2) and hinge, X 3, of same (3), and hinge, X 3, of a paratype (4), 

from Owl Creek, Tippah County, Miss. USGS 707, USNM 128147.

5. Holotype, X 2, a right valve, from the Owl Creek locality. USNM 128148.

6. 7. Two paratypes, one (6) an internal mold, X l}i of a right valve, and the other (7) a rubber cast, X 3, from 

the incomplete external mold of a left valve, from ditch on north-south road 1.4 miles west by south of Ardeola 

station, Stratford County, Mo. USGS 19090, USNM 128144.

8. Rubber cast from a paratype, X 3, an incomplete external mold of a right valve, from U. S. Highway 61, 1.6 miles

southwest of Benton, Scott County, Mo. USGS 16597, USNM 128146. 

9, 10. Cardium (Granocardium) tippanum Conrad, (p. 118).

9. Neotype, a right valve, from Owl Creek, Tippah County, Miss. USGS 707, USNM 76611. (Also illustrated in 

Miss. State Geol. Survey Bull. 40, pi. 12, figs. 1, 2, 1940, using old cat. No. 20853.)

10. Rubber cast from incomplete external mold of a large right valve, from a dry branch 300 feet downstream from

a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128143. 

11-16. Crassatella vadosa ripleyana (Conrad), (p. 117).

II-14. Views of three topotypes, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128139.

15. Rubber cast from external mold of anterior part of a right valve, from road cut in southeast-facing slope of 

Crowleys Ridge 0.35 mile northwest of Ardeola station, Stoddard County, Mo. USGS 16429, USNM 128141.

16. Internal mold of left valve of a young shell, from ditch on north-south road 1.4 miles west by south of Ardeola

station, Stoddard County, Mo. USGS 19090, USNM 128140. 

17-21. Liopistha protexta (Conrad), (p. 116).

17-19. Two plesiotypes, left (17) and right (18) valves, each, X 2, and hinge, X 3, of the right valve, from Owl 

Creek, Tippah County, Miss. USGS 707, USNM 128136.

20. Rubber cast, X 3, from incomplete external mold of left valve, from southeast-facing slope of Crowleys Ridge 

0.35 mile northwest of Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128135.

21. Internal mold, X 2, with ribs impressed upon it, from a dry branch 300 feet downstream from a road crossing 

2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128134.
PLATE 20

[Figures natural size except as indicated]

FIGURE 1. Cardium (Pachycardium) spillmani (Conrad), (p. 120).

Internal mold, X 2, of the right valve of a juvenile shell, from road on southeast-facing slope of Crowleys Ridge 0.35

mile northwest of Ardeola, Stoddard County, Mo. USGS 16452, USNM 128149. 

2-4. Aphrodina tippana (Conrad), (p. 120).

2. Left valve of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128154.

3. 4. Incomplete internal molds, one (3) a left valve, X 1%, and the other (4) a right valve, from ditch on north-south

road 1.4 miles west by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128153. 

5-7. Legumen ellipticum Conrad (p. 121).

5. Left valve, X 1& of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128158.

6. 7. Internal molds, X 1& of two young shells, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest of Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128157. 

8-11. Tenea parilis (Conrad), (p. 121).

8, 9. Plesiotype (= topotype?), aright valve, X 1%, and hinge of same, (X 3), from Owl Creek, Tippah County, Miss.

USGS 707, USNM 128160. 

10,11. Internal molds, X 1J4, of left and right valves, from ditch on north-south road 1.4 miles west by south of Ardeola

station, Stoddard County, Mo. USGS 19090, USNM 128159. 

12-14. Tellina buboana Stephenson, n. sp. (p. 121).

12. Right valve, X 2, of holotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 20706.

13. Hinge, X 5, of right valve of a paratype from the same locality. USGS 707, USNM 128161.

14. Internal mold, X 2, of a right valve, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128162. 

15, 16. Leptosden bipUcatus (Conrad), (p. 123).

15. Left valve of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128167.

16. Internal mold, X 2, of a small left valve, from ditch on north-south road, 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128166. 

17-25. Linearia metastriata Conrad (p. 122).

17. 18. Right valve, X 3, and interior of same, X 3, from Owl Creek, Tippah County, Mo. USGS 707, USNM 20713.

19. Interior of left valve, X 3, from the same source, USNM 20713.

20. Hinge of a right valve, X 3, from the same source. USNM 20713.

21-23. Rubber cast, X 2, of external mold of left valve (21), and internal molds, X 1%, of a right valve (22) and a

left valve (23), from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard County, Mo.

USGS 19090, USNM 128164. 

24, 25. Exterior of left valve, X 2, and interior of right valve, X 3, from Coon Creek tongue of Ripley formation at

Coon Creek, McNairy County, Tenn. USGS 10198, USNM 128165. 

26-28. Cyprimeria alta (Conrad), (p. 120).

26, 27. Exterior and interior views of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128155. 

28. Internal mold of a right valve, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest of Ardeola

station, Stoddard County, Mo. USGS 16429, USNM 128156.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 20

-./ 's

26 28 23 x 1% 27 

CARDILM, APHRODINA, LEGUMEN, TENEA, TELLINA, LEPTOSOLEN, LINEARIA, AND CYPRIMERIA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 21

GONIOCHASMA, NAPULUS, HELICAULAX, POLINICES, GYRODES, PSEUDOMALAXIS, GASTROCHAENA,

AND PANOPE
PLATE 21

[Figures natural size except as Indicated]

FIGUBE 1. Goniochasma? sp. (p. 124).

Internal mold, X 2, of left valve, from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard

County, Mo. USGS 19090, USNM 128172. 

2-5. Napulus octoliratus (Conrad), (p. 128).

2, 3. Two topotypes, X 2, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128190.

4, 5. Internal molds, X 2, from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard County,

Mo. USGS 19090, USNM 128191. 

6. Napulus? sp. (p. 129).

Rubber cast, X 2, from incomplete external mold, from a dry branch 300 feet downstream from a road crossing 2.1

miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128192. 

7-9. Helicaulax formosa Stephenson, n. sp. (p. 128).

7. Holotype, X 1>£ from Owl Creek, Tippah County, Miss. USGS 707, USNM 128189.

8. 9. Two incomplete internal molds, X 1%, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128187. 

10-12. Polinices rectilabrum (Conrad), (p. 125).

10, 11. Views of topotype, X 2, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128210.

12. Internal mold, X 2, from a dry branch 300 feet downstream from a road crossing, 2.1 miles southwest of Ardeola

station, Stoddard County, Mo. USGS 16451, USNM 128174. 

13, 14. Gyrodes spillmanii Gabb (p. 125).

Internal mold, X 2, and rubber cast, X 2, from external mold of same, from ditch on north-south road 1.4 miles west

by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128177. 

15, 16. Gyrodes supraplicatus (Conrad), (p. 125).

15. Apical view of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128176.

16. Apical view of an incomplete internal mold showing faint impressions of the characteristic crenations, from a dry 

branch 300 feet downstream from a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. 

USGS 16451, USNM 128175. 

17, 18. Gyrodes sp. (p. 126).

Views of an internal mold, X 2, from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard

County, Mo. USGS 19090, USNM 128178. 

19-21. Pseudomalaxis pateriformis Stephenson, n. sp. (p. 124).

19, 20. Top and bottom views, X 3, of the holotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 

20448.

21. Rubber cast, X 3, from bottom side of external mold, from ditch on north-south road 1.4 miles west by south of

Ardeola, Stoddard County, Mo. USGS 19090, USNM 128173. 

22, 23. Gastrochaena ripleyana Stephenson (p. 124).

22. Incomplete tube of a topotype, from Owl Creek, Tippah County, Miss. USGS 75, USNM 128170.

23. Internal mold of incomplete tube, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest of

Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128171. 

24-26. Panope monmouthensis Gardner (p. 123).

24. 25. Views of an incomplete shell, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128168. 

26. An incomplete internal mold of right jalve of a young shell from a dry branch 300 feet downstream from a road 

crossing 2.1 miles southwest of Ardeola station, Stoddard County, Miss. USGS 16451, USNM 128169.
PLATE 22

[Figures natural size except as indicated]

FIGURES 1-5. Liopeplum rugosum Stephenson, n. sp. (p. 130).

1, 2. Views of the holotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128200.

3. A medium-sized paratype, from the same source. USNM 128199.

4. 5. Two internal molds, from a dry branch 300 feet downstream from a road crossing 2.1 mites southwest of

Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128198. 

6-9. Morea transenna Stephenson, n. sp. (p. 129).

6, 7. Views of the holotype, X 2, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128194,

8. Back view, X 2, of a small paratype, from the same source. USNM 20443.

9. Rubber cast, X 2, from external mold, from ditch on north-south road 1.4 miles west by south of Ardeola station,

Stoddard County, Mo. USGS 19090, USNM 128193. 

10-12. Anchura? spp. (p. 128).

10. Rubber cast, X 1%, from incomplete external mold, from a dry branch 300 feet downstream from a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128185.

11. 12. Internal mold and rubber cast from external mold, of a shell from the same source. USNM 128186.

13. Fusinus"! sp. A (p. 130).

Internal mold, X 2, of a shell from ditch on north-south road 1.4 miles west by south of Ardeola station, Stoddard 

County, Mo. USGS 19090, USNM 128195.

14. Fusinusf sp. B (p. 130).

Rubber cast, X 2, from external mold of a shell from the preceding locality, USNM 128196.

15. Drilluta, sp. (p. 131).

Incomplete internal mold, X 2, from road on southeast-facing slope of Crowleys Ridge 0.35 mile northwest of

Ardeola station, Stoddard County, Mo. USGS 16429, USNM 128201. 

16-19. Turritella vertebroides Morton, sensu lato (p. 126).

16, 17, Views of a shell from Owl Creek, Tippah County, Miss. USGS 707, USNM 128181.

18, 19. Internal mold and rubber cast, X 1%, from external mold, of a shell from a dry branch 300 feet downstream from a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, 

USNM 128182. 

20-22. Turritella tippana Conrad (p. 126).

20. Front view of neotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 20419. This specimen 

was figured by Stuart Weller (1907, p. 700, pi. 79, fig. 6).

21. 22. Rubber casts, X 1% from incomplete external molds of two shells, from a dry branch 300 feet downstream 

from a road crossing 2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 

128179. 

23-25. Trobus buboanus Stephenson, n. sp. (p. 127).

23, 24. Views of the holotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 20423.

25. Fragment of distorted internal mold, from southeast-facing slope of Crowleys Ridge 0.35 mile northwest of 

Ardeola station, Stoddard County, Mo. USGS 16452, USNM 128184.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 22

24

LIOPEPLUM, MOREA, ANCHURA, FUSINUS, DRILLUTA, TURRITELLA, AND TROBUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 23

¥

26 29 27 30

VOLUTOMORPHA, EOHARPA, CAVEOLA, EOACTEON, BULLOPSIS, AND DISCOSCAPHITES
PLATE 23

[Figures natural size except as indicated]

Figures 1, 2. Volutomorphal spp. (p. 131).

1. Rubber cast, X \%, from incomplete external mold, from ditch on north-south road 1.4 miles west by south of 

Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128203.

2. Internal mold with sculpture impressed upon it, from a dry branch 300 feet downstream from a road crossing

2.1 miles southwest of Ardeola station, Stoddard County, Mo. USGS 16451, USNM 128204. 

3-6. Eoharpa sinuosa Stephenson, n. sp. (p. 132).

3-5. Views, X 1%, of the holotype, from Owl Creek, Tippah County, Miss. Figure 5 shows the band of tubercles

on the callus forming the forward part of the inner lip. USGS 707, USNM 20400. 

6. Rubber cast, X 1H, from incomplete external mold, from ditch on north-south road 1.4 miles west by south

of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128205. 

7. Caveola sp. (p. 132).

Rubber cast, X 3, from an external mold, from the preceding locality, USNM 128206. 

8-10. Eoacteon linteus (Conrad), (p. 133).

8, 9. Views, X 2, of a topotype, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128208.

10. Internal mold, X 2, with sculpture weakly impressed upon it, from ditch on north-south road 1.4 miles west

by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128207. 

11-19. Bullopsis cretacea Conrad (p. 133).

11-14. Views of three topotypes from Owl Creek, Tippah County, Miss.; 11, back view, X 2, 12, apical view, X 3,

13, 14, front and apical views, X 2. USGS 594, USNM 128221. 

15, 16. Front views, X 2, of two topotypes. USGS 707, USNM 128211.

17-19. Views, X 2, of an internal mold (17, 18) and rubber cast, X 3, from an external mold (19), from ditch on 

north-south road 1.4 miles west by south of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128209. 

20-22. Discoscaphites sp. (p. 135).

20. Side view of an incomplete shell, from Owl Creek, Tippah County, Miss. USGS 707, USNM 20861.

21. 22. Side and back views of an incomplete internal mold, from road on southeast-facing slope of Crowleys Ridge

0.35 mile northwest of Ardeola station, Stoddard County, Mo. USGS 16429. USNM 128219. 

[23-30. Discoscaphites iris (Conrad), (p. 134).

23-28. Views of three topotypes from Owl Creek, Tippah County, Miss.; 23-25 back, front, and side views, 26, 27 

back and side views, 28 interior view, X 2, showing septa of an inner volution. USGS 707, USNM 128218.

29, 30. Back and side views of an incomplete internal mold, from ditch on north-south road 1.4 miles west by south 

of Ardeola station, Stoddard County, Mo. USGS 19090, USNM 128217.
PLATE 24

[Figures natural size except as indicated]

FIGUBES 1-4. Sphenodiscus pleurisepta (Conrad), (p. 135).

1. Lateral view of a medium-sized shell, from Owl Creek, Tippah County, Miss. USGS 707, USNM 128183.

(Also illustrated in Miss. State Geol. Survey Bull. 40, pi. 13, fig. 6, 1940, under old cat. no. 20283.) 

2-4. Views of an incomplete internal mold of a large shell, from the southeast-facing slope of Crowleys Ridge 0.35

mile northwest of Ardeola station, Stoddard County, Mo. USGS 19088, USMN 128220; figure 4 is a cross section

of the large end of this specimen. The specimen was collected and donated to the United States Geological Survey

by Edison Shrum of Advance, Mo. 

5-9. Baculites carinatus Morton (p. 134).

5-7. Views of an incomplete plesiotype, from Owl Creek, Tippah County, Miss.; figure 7 is a cross section of the

large end of this shell. USGS 707, USNM 1282J5.

8. An incomplete younger shell, from Braddock's farm on Walnut Creek 7 miles northeast of Ripley, Tippah County, 

Miss. USGS 713, USNM 128216.

9. Rubber cast, X 2, from incomplete external mold of a young shell, from southeast-facing slope of Crowleys 

Ridge 0.35 mile northwest of Ardeola, Stoddard County. Mo. USGS J6452, USNM 128214.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 274 PLATE 24

SPHE^OD/SCLTS A^D BACLLITES