UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mcndenhull, Director

Professional Paper 190

LOWER PLIOCENE MOLLUSKS AND

ECHINOIDS FROM THE LOS ANGELES

BASIN, CALIFORNIA

AND THEIR INFERRED ENVIRONMENT

BY

W. P. WOODRING

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1938

For sale by the Superintendent of Documents, Washington, D. C. ------ Trice 30 cents
CONTENTS

Abstract._____________----______-_-_--

Introduction __________-_-___-___---_-_

New systematic names proposed_______-_

General features of Los Angeles Basin____

Repetto formation of Los Angeles Basin __ 

General features.___________________

Outcrop localities._-_--____-_-_____

Subsurface section.________________

Larger fossils from Repetto formation____

Outcrop localities._________________

Subsurface localities.---______.__-_-

Fossils. _ _-____-____---___-_-______.

Inferred environment of larger fossils.....

Depth range of allied modern species.

Page 

Inferred environment of larger fossils Continued.

Inferred depth range of larger fossils______________ 13

Interpretation of fossils of deep-water facies----.... 15

Distribution of fossils of different depth facies...... 16

Paleogeographic implications_____________________ 16

Bearing on geologic history of Los Angeles Basin.__. 17 

Comparison between Los Angeles Basin during 

Repetto time and modern deep-water basins on 

Continental Shelf of southern California._________ 18

Age relations of larger fossils.__________________'______ 18

Fossils of deep-water facies__-____________________ 18

Fossils of intermediate and shallow-water facies.____ 20

Descriptions of species_____-___--__-_-____-__-_.____ 22

Index.______.________________________ 65

ILLUSTRATIONS

Page 

PLATE 1. Relief map of California showing principal areas

of marine Pliocene formations._____________ 2

2. Generalized geologic map of Los Angeles Basin

and borders._----------------_-__----_-_ 2

3. Depth frequency graphs of modern Pacific 

coast mollusks and echinoids allied to Repetto fossils.-----------.-.-------------- 14

4. Map of Los Angeles Basin showing distribution

of Repetto fossils of different depth facies. _ _ _ 14 

5, 6. Pliocene and Miocene mollusks from Los Angeles Basin___----_-____-_____-_-____.___ 60,61

it

PLATE 7. Pliocene mollusks from Los Angeles Basin_____

8. Pliocene mollusks from Los Angeles Basin and 

Miocene mollusks from Colorado Desert.

9. Pliocene mollusks and echinoids from Los 

Angeles Basin___________________________

FIGURE 1. Bathymetric map of Continental Shelf along 

part of coast of southern California. _______

2. Hinge of Phreagena, Calyptogena, and Eclenagena. _________-_____-________----__

Page

62

63

64

19

50
LOWER PLIOCENE MOLLUSKS AND EG^INOIDS FROM THE LOS ANGELES BASIN, 

CALIFORNIA, AND THEIR INFERRED ENVIRONMENT

By W. P. WOODRING

ABSTRACT

The Repetto formation, which is considered of lower Pliocene 

age, embraces the principal oil-bearing strata in most of the major 

oil fields of the Los Angeles Basin. Twenty-six forms of mollusks. 

and one echinoid are described from the Repetto formation of 

this region, and other larger fossils are recorded. These fossils, 

were collected from outcrops and from cores representing 56 wells 

distributed widely over the basin. Imperfect remains from 10 

additional wells are undetermined or undeterminable.

The fossils are assigned to three depth-range groups on the 

assumption that they represent essentially the same depth range 

as modern species from the eastern Pacific, to which the}7, are 

closely allied. These groups are (J) fossils of shallow-water 

facies; (2) fossils of intermediate-depth facies, inferred to represent a range from shallow water into deep water; (3) fossils of 

deep-water facies.

The fossils of deep-water facies consist of at least 8 species, 

possibly .1.2 species, embracing mollusks, an echinoid, a sponge, 

and doubtfully a coral. The first fossil representatives of the 

echinoid family Echinothuriidae found in America are included 

in this group. Inasmuch as the fossils of deep-water facies belong 

to genera or subgenera that, with one exception, have not been 

found in California Pliocene formations characterized by a 

shallow-water facies, it is inferred that they represent deep water 

or cool water. The hypothesis that they represent upwelling 

cool water is considered and rejected, and the probability that 

they lived in deep water is considered reasonably certain. Most 

of the deep-water fossils are closely allied to species dredged by 

the Albatross off the coast of Oregon arid California, but some 

closely resemble species that have not yet been found north of 

Central America, and allies of one species of probable deep-water 

facies are unknown in the eastern Pacific.

The fossils of deep-water facies are widely distributed throughout the basin. They suggest that during Repetto time the Los 

Angeles Basin sea had depths of 300 to 600 fathoms (roughly 

2,000 to 4,000 feet).

Fossils of shallow-water .facies have so far been found near the 

northern border of the basin and near the western margin. The 

fossils of intermediate-depth facies are more widely distributed 

than those of shallow-water facies. Some evidence points to 

areas of shallow water near the northern border of the basin. 

The association of fossils of deep-water, intermediate, and shallowwater facies and of land fossils in part of this region, however, 

suggests proximity to land and transportation of the shallowwater and land fossils by unknown agencies. The source of a 

shallow-water fossil from a locality near the western margin of 

the basin is not known but may have been an area of shallow 

water farther south.

The widespread distribution of fossils of deep-water facies in 

the Repetto formation and the depth facies of the overlying Pliocene and Pleistocene formations support the interpretation, 

already suggested, that the deposition of sediments of decreasing

depth facies during Pliocene and Pleistocene time was a factor 

in the accumulation of the 6,000 to 10,000 feet of Pliocene and 

Pleistocene sediments in the basin. Unless, however, the depth 

of the Repetto sea was much greater than now appears probable, 

subsidence also was a factor.

The inferred deep-water environment of the Repetto formation 

supports the comparison, also already made, of the Los Angeles 

Basin during Repetto time with the modern deep-water basins 

on the Continental Shelf of southern California. These modern 

basins have depths of 300 to 1,000 fathoms. According to recent 

investigations, sand is being deposited on the ridges between the 

modern basins regardless of depth, and the fine-grained sediments 

in the basins are relatively rich in organic matter.

The age relations of the fossils are briefly discussed. Most of 

the fossils of deep-water facies closely resemble modern species, 

and many are similar to Miocene and Oligocene forms. The 

shallow-water species have a middle Pliocene aspect in terms of 

current age assignments.

INTRODUCTION

The Repetto formation, which is assigned to the 

lower Pliocene, embraces the principal oil zones in most 

of the major oil fields of the Los Angeles Basin. The 

extensive foraminiferal fauna of this formation^ tjas 

been exhaustively studied on account of its value in pil|- 

field correlations, but the results of these studies have 

not yet appeared in print aside from a few brief accounts 

dealing with single species or local areas. Apparently 

only one record of a Repetto larger fossil* from core 

material in the basin has been published. 2

I am greatly indebted to Dr. W. S. W. Kew, of the 

Standard Oil Co. of California, and to Mr. S. G. Wissler, 

of the Union Oil Co. of California, for the opportunity 

.to study Repetto larger fossils from 60 wells distributed 

over the-basin. These fossils have accumulated in the 

Standard and Union micropaleontology laboratories 

during the last few years. The officials of these companies and of other companies whose wells are represented in the core collections kindly gave permission to 

publish the data on the fossils. Mr. Wissler also permitted publication of records of Lima hamlini and 

Hyalopecten aff. H. randolphi tillamookensis based on 

specimens in his laboratory from six additional wells.

1 The term "larger fossils" is used to contrast mollusks, echinoids, and other relatively large fossils with microscopic ones; it corresponds to the term "rnegafossils."

8 Hertlein, L. G., New species of marine fossil Mollusca from western North 

America: Southern California Acad. Sci. Bull., vol. 24, p. 43, pi. 4, flg. 6,1925. .
LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Dr. Kew presented to the National Museum the material accumulated under his direction. Mr. Wissler 

donated to the Museum the types, other figured specimens, and additional material from his collection; the 

other specimens from his collection have been returned 

to the Union Oil Co.'s laboratory. Mr. Alex Clark, of 

the Shell Oil Co., donated to the Museum the specimen 

of Lunatia cf. L. caurina from the Inglewood field; 

permitted publication of the record of Lima hamlini, 

based on the specimen in his collection from the excavation for the Times Building in Los Angeles; and guided 

me to collecting localities in the Repetto Hills.

It is to be hoped that additional material will be 

collected as cores are sampled, for almost any Repetto 

larger fossil is of interest. A special effort should be 

made to collect Repetto larger fossils from wells in the 

Ventura Basin. It is quite probable that some events 

in the Pliocene history of the Los Angeles Basin and the 

Ventura Basin were similar. Repetto larger fossils 

resembling in facies those from the Los Angeles Basin 

might be expected to occur in the Ventura Basin. 

Apparently no record of Repetto larger fossils from 

cores taken in Ventura Basin wells has been published.

In addition to the core material, outcrop collections 

from Los Angeles, the Repetto Hills, and the Palos 

Verdes Hills all along the border of the Los Angeles 

Basin were studied in the preparation of this report. 

Several small collections were recently gathered in Los 

Angeles by Mr. W. H. Holman, of the Standard Oil 

Co. of California. The principal material from Los 

Angeles was collected by Homer Hamlmin 1901, when 

the Third Street tunnel was excavated between Hope 

Street and Hill Street. Hamlin's collection furnished 

material for the description of several new species. A 

list of the fossils from the Third Street tunnel was published by Ralph Arnold in 1907. W. H. Dall and Arnold 

recognized that the fossils from the Third Street tunnel 

are of Pliocene age. Material collected in the type 

region of the Repetto formation in the Repetto Hills 

is not included in the description of species, aside from 

the specimens of "Nassa" hamlini and Acila semirostrata. These collections from the Repetto Hills represent horizons assigned by micropaleontologists to the 

transition zone between the Repetto formation and the 

overlying Pico formation. Lists of species in the collections from the Repetto Hills are included in the 

discussion under the heading "Age relations of larger 

fossils."

The sponge remains were identified by Dr. M. W. 

de Laubenfels, of Pasadena; the corals by Dr. J. E. 

Hoffmeister, of the University of Rochester; the decapod crustaceans by Dr. M. J. Rathbun, of the United 

States National Museum; the echinoids by Dr. Th. 

Mortensen, of the Zoological Museum of the University 

of Copenhagen, and Dr. A. H. Clark, of the United 

States National Museum; and the plants by Mr. R. W. 

Brown, of the United States Geological Survey. Dr.

Mortensen kindly permitted use of his identification and 

comments on the echinothuriids. I prepared the description of the echinothuriid material under the supervision of Dr. A. H. Clark. Mr. H. L. Driver, of the Standard Oil Co. of California, verified the stratigraphic data 

for the specimens in the Standard collection. Mr. Wissler 

prepared a chart showing the stratigraphic distribution 

of the larger fossils with reference to foraminiferal 

zones. Though the data on this chart are cited only 

in general terms, they were very useful in attempting 

to interpret the significance of the fossils. Dr. L. G. 

Hertlein, of the California Academy of Sciences, loaned 

specimens for comparison. Mr. D. D. Hughes, of the 

Texas Co. (California), supplied information about a 

locality on Newport Lagoon. Dr. H. A. Pilsbry, of 

the Philadelphia Academy of Natural Sciences, kindly 

made available the type lots of Ostrea vespertina and 

Ostrea veatchii. Mr. W. E. Schevill, of the Museum of 

Comparative Zoology, kindly loaned material from the 

type lot of Pecten peckhami and presented to the National Museum a squeeze of the lectotype. This study of 

Repfctto mollusks could not have been attempted without access to. the dredgings of the United States Fish 

Commission steamer Albatross from the eastern Pacific, 

and I wish to acknowledge my indebtedness to Dr. Paul 

Bartsch, Dr. H. A. Render, and Dr. J. P. E. Morrison, 

all of the Division of Mollusks of the United States 

National Museum, for facilities and courtesies. The 

manuscript, except the systematic paleontology, was 

read by Dr. Kew and Mr. Wissler, and the entire 

manuscript was read by several of my colleagues on 

the Geological Survey. I have profited from their 

criticisms and suggestions.

NEW SYSTEMATIC NAMES PROPOSED 

The following new names are proposed:

Limopsis (Felicia) phrear, n. sp. (p. 31).

Phreagena, n. gen., Vesicomyacidae?. Type, Phreagena

lasia, n. sp. (p. 50). 

Ectenagena, n. gen., Vesicomyacidae. Type, Calyplogena

elongata Dall (p. 51). 

Periploma cryphia, n. sp. (p. 56). 

Periploma cryphia stenopa, n. var. (p. 57).

GENERAL FEATURES OF LOS ANGELES BASIN

The principal areas of marine Pliocene formations in 

California are found in relatively small regions extending inland from the present coast, aside from the extensive inland San Joaquin Basin and its seaward 

prolongation and the Santa Rosa region. As shown on 

plate 1, the Los Angeles Basin is one of these coastal 

regions. The term "Los Angeles Basin" is here used 

in a physiographic sense for the lowland extending 

seaward from Los Angeles. The basin is bounded on 

the north by the Santa Monica Mountains and by 

hills extending southeastward from the Santa Monica 

Mountains to the Santa Ana Mountains, including the 

Repetto Hills and the Puente Hills; on the east by the
GBOLOGICAL SURVEY PROFESSIONAL PAPER 190 1'I.ATE I

Ee/ R/yer 

Bas/'n.

Sta

San franc/sco BCLV '~^^"'^'->

San Di

RELIEF MAP OF CALIFORNIA SHOWING PRINCIPAL AREAS OF MARINE PLIOCENE FORMATIONS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 150 PLATE 2

!!3 33o'

^ &V''-\ ^^^^^^^^>fc^^^

-O^'-'V'^ ^^--M^\-/^^^^^<T'/^C^\s^/ ^o-'/s^X ^^V^Y--r '-~-"-^^/ ^)0()/N<:w/-

Fernando 0 SuT^ap;k^,O ^>£V^:; '.'- -. : /. '-V?3^>^^ '; 'A>/'/>

/a'' e v vXf-/x^/'x^-' ^Vi\' -' ' - ' ' "' V' ^'-^^^O^V^Uvj 

y - V^^/ wVv ^/^.,V -. - - -.-. .'* ^>^Qa:y'*(y//-Q^jy

.<l i££a£ .-Mc^.cfe.-pi^-^:-". \l : /-^^^v

San Bernardmo 

Valley

Qaly

.; .-..-. Qaio -.; . .'. 

. .' '. '-. '.' *"

 ELSEGUNDO ' .' ' '. . , .' > 

O V .' Cr* ' '' ' ROSECRAN&vV'. 

 \ .' /'.'.'"LAWNDALE.-. 

>

EXPLANATION 

SED.'.VSENTARY ROCKS

Younger a!!uv;urr: 

(6ravel,saftcf, silt, clay, undissecied}

Older aliuviurr;

(Gravel, sand, sift,c/ay; soil reddish or

brownish; dissected and at places folded

and faulted. Near coast includes rnarjne

beds at base; along west coast includes

wind-blown sand, now stationary)

Early Pleistocene marine deposits 

(Gravel, sand, silt, marl. Includes some 

nonmarine beds)

Pliocene marine

(Siltstone, I *-rtr I ij t \si i^, sandstone, Ob*f«M^ . \str*^r conglomerate. i^ls* i y.vf/f cr utc^'

includes some nonmarine P/e/stocenef?)

Miocene marine and Oligocene(?)

nonmarine deposits

("Marine porcelaneous and.cherty shale,

diatomaceous clay.radiolarian mudstone.

sitty shale, sandstone, conglomerate',

nonmarine red and a re en cloy, sandstone, conglomerate)

Eocene marine deposits

(Shate.sands'tone, conglomerate)

Cretaceous marine deposits

(Shale, sandstone conglomerate. // 

5 anta Monica Mountains /nc/udes

basal Eocene)

i / //y///ic, , j/utc. s/ate. &c,///z>c schist, t our/uofone. sane/stone, /n/n

SantaAna. Mountains includes andesitic 

 2nd gran it/c rocfis. May include some Jurassic)

METAMORPHIC AND IGNEOUS ROCKS

Basalt and andesite

(Intrusive and extrusive)

Granodiorite

Franciscan.(?) schist

(Soda amphibo/e schist and other schist)

Basement complex 

(Schis^gneiss^ndgranite and basic fntrusives)

4- Faults

o it 

o u

D2 

T <

4-

10 Miles

Crest of anticline Trough of syncline 

OiFffeld

10 Kilometers

GENERALIZED GEOLOGIC MAP OF LOS ANGELES BASIN AND BORDERS. 

After Hoots and Kew (16th Internal. Geol. Cong. Guidebook 15, pi. 6, 1932) and Eckis (California Dm Water Resources Bull. 45, pis. A, B, C, 1934). Modifications from original sources in area covered by Palos Verdes Hills.
REPETTO FOKMATION OF LOS.ANGELES BASIN

foothills of the Santa Ana Mountains and the San 

Joaqnin Hills; on the south by the ocean and the Palos 

Verdes Hills (or San Pedro Hills); and on the west by 

the ocean. (See pi. 2.) The basin includes the flat 

seaward-sloping Los Angeles Plain, low hills enclosed 

by the plain, and mesas that rise above the plain along 

part of the bordering uplands. As thus defined the 

basin has an area of about 800 square miles.

The term "Los Angeles Basin" is also used for the 

Tertiary and Pleistocene depositional basins. During 

Pliocene time the sea extended beyond the present 

physiographic basin. The Miocene basin was also 

much more extensive than the present basin. At that 

time the sea extended entirely across the Santa Monica 

Mountains, the Palos Verdes Hills, and the San 

Joaquin Hills; covered part of the Santa Ana Mountains; 

and extended northward at least to the foot of the 

present 'San Gabriel Range. Possibly the Miocene 

sediments within the northern part of the present basin 

are thicker than in the bordering uplands, but only the 

upper part of the Miocene has so far been reached by 

wells within this part of the basin. The pre-Miocene 

history of the basin is not known. In the Santa Monica 

Mountains and the Santa Ana Mountains a thick 

succession of nonmarine Oligocene (?) and marine 

Eocene, Upper Cretaceous, and Triassic formations 

(the last not dated in the Santa Monica Mountains) 

lies below the Miocene. These formations may underlie 

the northern part of the basin, north of the NewportInglewood uplift. Seismic observations are interpreted 

as indicating that the basement, presumably consisting 

of granitic rocks, is at a depth of about 45,000 feet in 

the syncline northeast of the uplift.3 In the Palos 

Verdes Hills and also in the Wilmington, Torrance, 

Playa del Rey, and El Segundo fields south of the 

Newport-Inglewood uplift, which is thought by many 

geologists to mark a deep-seated fault Miocene rests 

directly on a basement of Franciscan (?) schist of 

Jurassic (?) age. 4 It has been suggested that if a deepseated fault lies along the Newport-Inglewood uplift, 

the fault probably marks the boundary between. the 

Franciscan. (?) basement and the granitic basement. 5 

Brief accounts of the geology of the basin and its 

borders have recently appeared.6 Plate 2 is a generalized geologic map of the basin and its borders. Most 

of the major oil fields of the basin he along two northwestward-trending lines of anticlines the Coyote Hills

* Outonborg, B., and Buwakla, J. P., Seismic reflection profile across Los Angeles 

Basin (abstract): Cleol. Soc. America Proc., 1935, pp. 327-328, 1936.

4 See Woodrlug, W. P., Brarnlette, M. N., and Kleinpell, R. M., Miocene stratigraphy and paleontology of Palos Vordos Hills, California: Am. Assoc. Petroleum 

Geologists Bull., vol. 20, pp. 133, 140, 142, flg. 3, 1936.

J Rood, R. D., and Hollister, J. S., Structural evolution of southern California: 

Am. Assoc. Petroleum Geologists Bull., vol. 20, pp. 1678-1679, 1936.

"Hoots, H. W., General geology of the Los Angeles Basin: 16th Internat. Gcol. 

Gong. Guidebook 15, pp. 23-20, pi. 0, flgs. 1-2, 1932. Eckis, Rollin, South Coastal 

Plain investigations; Geology and ground-water storage capacity of valley fill: California J5iv. Water Resources Bull. 45, pp. 23-76, pis. A-.D, 1934. Hoots, H. W., and 

Horold, S. C., Natural-gas resources of California: Geology of natural gas, pp. 172-220, 

flgs. 10-30, Tulsa, 1935. Reed, R. D., and Hollister, J. S., op. cit., pp. 1658-1681, 

flgs. 42-48, pi. 9,1936. I

uplift and the Newport-Inglewood uplift. The largest 

fields are Santa Fe Springs and Long Beach, which 

together have produced about 1,000,000,000 barrels of 

oil since they were discovered in 1921. Other fields are 

located on anticlines in the basin and on anticlines and 

faulted monoclines along the northern border of the 

basin. The principal oil-bearing strata are in the lower 

Pliocene Repetto formation, in which the fossils 

described in this report were found. In some fields 

productive zones are found also in the overlying Pico 

formation and in the underlying Miocene.7

The Los Angeles Basin has a general basinlike structure, except at the seaward margins. At many places, 

however, the structure of the border of the basin is 

modified by faults and folds. In part of the city of 

Los Angeles the structure is relatively simple, and 

Pliocene strata dip toward the basin. Also in the 

Repetto Hills, in part of the Puente Hills, and in the 

Palos Verdes Hills Pliocene and Pleistocene formations 

dip basinward.

REPETTO FORMATION OF LOS ANGELES BASIN

GENERAL FEATURES

The Pliocene of the Los Angeles Basin and bordering 

hills was assigned long ago to the Fernando formation, 

a name introduced by Eldridge and Arnold.8 Kew 9 

raised Fernando to group rank to include the newly 

defined Pico formation and Hershey's Saugus formation, 

the type regions of both being in the Santa Clara 

Valley, in the Ventura Basin. (For location of Ventura 

Basin see pi. 1.) After the Pico formation was defined 

the Pliocene of the Los Angeles Basin and its borders 

was assigned to the Pico. When the succession of 

foraminiferal zones in the Pliocene subsurface section 

of the basin was worked out, it was evident to micropaleontologists that two well-marked major faunal 

divisions are represented, which were designated by some 

geologists lower Pico and upper Pico. After the outcrop sections were sampled and studied it was found 

that the lower faunal division may not be represented 

in the type region of the Pico on the south side of the 

Santa Clara Valley or, if represented, has a different 

facies. The lower division in the Los Angeles Basin 

accordingly was designated lower Pliocene and the 

upper division Pico. Finally a committee of the Pacific 

section of the Society of Economic Paleontologists and 

Mineralogists in 1930 proposed to use the new name 

"Repetto formation" for the lower division in the Los 

Angeles Basin and Pico formation for the upper division. 

The Repetto formation was first defined in print in 

1932. 10 Some field geologists object to this classifica7 See Hoots, H. W., Oil development in the Los Angeles Basin: 16th Internat. 

Geol. Cong. Guidebook 15, table opp. p. 26,1932.

e Eldridge, G. H., and Arnold, Ralph, The Santa Clara Valley, Puente Hills, and 

Los Angeles oil districts: TJ. S. Geol.'Survey Bull. 309, p. 22,1907.

8 Kew, W. S. W., Geology and oil resources of a part of Los Angeles and Ventura 

Counties, Calif.: TJ. S. Geol. Survey Bull. 753, pp. 69-70, 1924.

10 Reed, R. D., Section from the Repetto Hills to the Long Beach oil field: 16th 

Internat. Geol. Cong, Guidebook 15, p. 31, footnote, 1932.
LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

tion and nomenclature. They claim, that the two formations are similar in field characters and that they are 

differentiated principally by their foraminiferal faunas. 

Such geologists continue to use lower Fernando and 

upper Fernando, or similar terms, for the two divisions. 

Inasmuch as faunal divisions do not constitute a satisfactory basis for subdividing into formations an essentially uniform lithologic sequence, this objection 

deserves consideration. Pending a consideration of 

this matter, the term "Repetto formation" is here used, 

as it has the advantage of essentially unequivocal significance to geologists and paleontologists familiar with 

' this region.

If the upper faunal division is to have a formation 

name, it is doubtful whether the name "Pico formation" 

is an appropriate one. The usage of this name implies 

correlation with the type region of the Pico in the 

eastern part of the Ventura Basin. The implied correlation rests on faunal grounds. When the name 

"Repetto formation" was proposed it was recognized 

that the type region of the Pico formation may include 

deposits of Repetto age represented by a different facies. 

The implied correlation between the Los Angeles and 

Ventura Basins may rest on a correlation of faunal 

facies and not on a correlation of chronologic successions 

of faunas.

OUTCROP LOCALITIES

Repetto Hills, The type region of the Repetto 

formation is in the basinward-dipping monocline in the 

Repetto Hills on the north side of the basin described 

by Driver, Holman, and Ferrando,12 Reed, 13 and 

Edwards. 14 Here the formation consists of 2,000 to 

2,500 feet of buff siltstone. All except the lowest few 

hundred feet of the formation is exposed almost continuously in street cuts along the west side of the valley 

followed by Atlantic Boulevard (through the "o" of 

"Repetto" in "Repetto Hills" of pi. 2). The Repetto 

rests conformably on diatomaceous shale referred to the 

Miocene Puente formation (Modelo formation of some 

geologists andMonterey formation of others). The top 

of the Repetto is drawn "at the top of three beds of 

coarse feldspathic sandstone ranging in thickness from a' 

few inches to several feet." 15 Overlying the thin beds of 

sandstone at the top of the formation is siltstone 

carrying, according to Reed, a mixture of Repetto and 

Pico Foraminifera (the transition zone of micropaleontologists), above which is the siltstone assigned to the 

Pico formation. Mollusks collected from beds assigned 

to .the transition zone in this section are considered 

under the heading "Age relations of larger fossils."

13 Driver, H. L., Holman, .W. H., and Ferrando, A., Foraminiferal section in 

Repetto Hills (unpublished report presented before Pacific section of Society of 

Economic Paleontologists and Mineralogists, 1928).

is Reed, R. D., op. cit., pp. 31-33; Geology of California, pp. 239-240, Tulsa, 1933.

14 Edwards, E. C., Pliocene conglomerates of Los Angeles Basin and their paleogeographic significance: Am. Assoc. Petroleum Geologists Bull., vol. 18, pp. 795-796. 

1934.

1« Reed, R. p., op. cit., p. 3}, footnote, 193?.

Puente Hills. The Pliocene of the Puente Hills, east 

of the Repetto Hills, embraces thick units of conglomerate and sandstone as well as siltstone. 16 According to Edwards, the pebbles in the conglomerates were 

derived from the Perris Plateau, which now stands at a 

relatively low altitude northeast of the Puente Hills, 

beyond the eastern limit of the area shown on plate 2. 

Foraminifera of Repetto and Pico age have been found 

in the Pliocene of the Puente Hills,17 but there is no 

published record of a subdivision of the Pliocene section. 

According to recent investigations, the lower part of the 

5,000-foot section assigned by English to the Fernando 

group is of Miocene age. 18 Mollusks from the Pliocene 

of this region are mentioned under the heading "Age 

relations of larger fossils."

San Joaguin Hills. Lower Pliocene and upper 

Pliocene siltstone and sand at the west end of the San 

Joaquin Hills, which lie along the southeastern" border 

of the basin, were mentioned by Edwards. 19 According 

to a communication from Kew, Holman has found larger 

fossils in the lower Pliocene of this region. Strata 

apparently assignable to the upper Pliocene contain an 

Acila, probably the same as one in the subsurface 

Repetto (Acila semirostrata}.

Polos Verdes Hills. The only Pliocene formation 

recognized in the Palos Verdes Hills (or San Pedro 

Hills), on the south border of the basin, consists of gray 

to buff siltstone containing Repetto Foraminifera. 20 

The best exposures are in a synciine on the sea cliff at 

Malaga Cove, at the northwest end of the hills. (The 

synciine is shown on pi. 2, but tHe scale of the map is 

too small for an adequate representation of the geology.) 

At this locality a thickness of 85 feet of siltstone is well 

exposed, and an estimated additional thickness of about 

65 feet is concealed by slump at the top of the cliff. 

The siltstone of the Repetto formation at Malaga Cove 

lies conformably on the Malaga mudstone member of, 

the Monterey shale (Puente shale of some geologists 

and Modelo shale of others), which is considered of 

upper Miocene age.21 At most accessible places on the 

cliff the contact between the two units appears to be 

gradational through a thickness of a few inches. About 

halfway up the cliff on the south limb of the synciine a 

lens of sand 1 foot thick lies between the brown radio16 English, W. A., Geology and oil resources of the Puente Hills, southern California: U. S. Geol. Survey Bull. 768, pp. 39-44, 1926. Edwards, E. C., op. cit., pp. 

800-803.

17 Stewart, R. E., and Stewart, K. C., "Lower Pliocene" in eastern end of Puento 

Hills, San Bernardino County, Calif.: Am. Assoc. Petroleum Geologists Bull., vol. 

14, pp. 1445-1450, 1 fig., 1930. Edwards, E. C., op. cit., p. 802.

18 Krueger, M. L., The Sycamore Canyon formation [abstract]: Am. Assoc. Petroleum Geologists Bull., vol. 20, p. 1520, 1936. 

" Edwards, E. C., op. cit., pp. 803-804.

20 Reed, R. D., A siliceous shale formation from .southern California: Jour. Geology, 

vol. 36, pp. 342-361, 4 figs., 1928. (The "foraminiferal rock" described on pp. 353-357 

represents the Repetto formation. The "nonfojaminiferal siliceous shale" is now 

assigned to the Valmonte diatomite member and the Malaga mudstone member of 

the Monterey shale, both considered of upper Miocene age.) Woodring, W. P., San 

Pedro Hills: 16th Internat. Geol. Gong. Guidebook 15, pp. 38, 40, fig. 6, 1932. Edwards, E. C., op. cit., p. 804.

21 WpQdring, W, P., Bramlette, M, N., and Kleinpell, R. M., op. cit., pp. 146-148,
REPETT.O FORMATION OF LOS ANGELES BASIN

larian mudstone of the Malaga and the gray glauconitic 

foraminiferal siltstone of the Repetto. The Rep.etto is 

unconformably overlain by sand assigned to the Palos 

Verdes sand, of late Pleistocene age. Elsewhere in the 

Palos Verdes Hills lower Pleistocene strata unconformably overlie the Repetto. The Repetto at Malaga 

Cove contains two thin beds of fine-grained vitric 

volcanic ash, which has been examined by M. N. 

Brainlette. Isolated small pebbles of schist and black 

basaltic rock are found in a few places. A caudal 

vertebra of a whale, identified by Dr. Remington 

Kellogg, of the United States National Museum, was 

. collected by H. W. Hoots about 10 feet above the base 

of the formation. A few specimens of Lima hamlini, 

the most abundant and widespread of the larger fossils 

in the Repetto of the basin, have been found in a thin 

zone 5 to 10 feet below the lower bed of volcanic ash on 

tbe north limb of the syncline.

Other outcrops of buff siltstone of the Repetto formation have been recognized at the head of the fourth 

ravine west of Walteria, where fragmentary remains of 

Lima hamlini were found, at Lomita Quarry, and in an 

a.rea straddling Western Avenue. These localities are 

near the north edge of the Palos Verdes Hills and, with 

the exception of the small area in the ravine near 

Walteria, are shown on a recently issued generalized 

geologic map. 22 Farther east the Repetto is overlapped by lower Pleistocene strata that rest unconformably on different parts of the Miocene.

Santa Monica Mountains. Potrero Canyon (the 

second canyon .northwest of Santa Monica shown on 

pi. 2) is the only locality along the foot of the Santa 

Monica Mountains where strata, of Repetto age have 

been found. At this locality an isolated section of 

Pliocene deposits is revealed under the cover of the 

Santa Monica Plain. 23 As described by Hoots, this 

Pliocene section consists of about 1,000 feet of mountainwa,rd-dipping clay shale and sandy clay shale, 

faulted against Miocene shale at several places. Angular fragments of limestone in the Pliocene sediments 

apparently were derived from the underlying Miocene. 

A foraminiferal fauna of Repetto age characterizes the 

lower part of the section, and one of Pico age the upper 

part. Larger fossils were found in the Pico formation, 24 

and, according to a communication from Kew, Holman. has recognized fragmentary remains of Lima 

hamlini and Fusitriton in the Repetto formation.

Los Angeles. Exposures of the Repetto formation 

are accessible in street cuts in Los Angeles close to the 

north, edge of the Los Angeles Plain. The Pliocene 

section, in this region, which has a thickness of 900 to 

1,275 feet according to a communication from Kew,

« Woodring, W, P., Bramlcttc, M. N., and Kleinpoll, R. M., op. cit., fig. 1.

85 Hoots, H. W., Geology of the eastern part of the Santa Monica Mountains, Los 

Angeles County, Calif.: U. S. Oool. Survey Prof. Paper 105, pp. 115-119, 1931. In 

addition to the geologic map (pi. 10), see pi. 27.

« Wooclring, W. P., in Hoots, H. W., idem, p. lie.

has been described by Holman, Ferrando, and Driver,25 

Soper and Grant, 26 and Edwards.27 Siltstone carrying 

Repetto Foraminifera rests conformably on Miocene 

diatomaceous shale, as in the Repetto Hills. According to a communication from Kew, the thickness of the 

Repetto ranges from 600 to 975 feet, and the thickest 

sections are found in the eastern part of the area. Thin 

beds of conglomerate, described by Edwards, are found 

at a horizon about 500 feet above the base of the formation. They consist predominantly of limestone 

pebbles, chips, and slabs, which are thought by Edwards to have been derived from the Miocene nearby. 

Soper and Grant divided this Pliocene section into 

three parts. Their structure section shows an unconformity between their lower Pliocene and middle Pliocene and a disconformity between their middle Pliocene 

and upper Pliocene.

The collection of fossils made by Hamlin when the 

Third Street tunnel was excavated in Los Angeles is 

the largest one studied in the preparation of the present 

report. These fossils, which were assigned to the 

upper Pliocene by Gale 2S and to the middle Pliocene 

by Grant,29 are considered further under the next 

heading. Other collections of Repetto fossils have 

recently been made in Los Angeles by W. H. Holman, 

of the Standard Oil Co. of California. Larger fossils 

from a horizon in the Pico formation near the top of 

the exposed section have been listed and discussed by 

Moody 30 and Grant.31

SUBSURFACE SECTION

The Repetto of the subsurface section in the Los 

Angeles Basin has been briefly described in recent accounts by Hoots 32 and by Hoots and Herold.33 Data 

on the character and thickness of the formation are 

presented in reports on Los Angeles Basin oil fields 

issued in the "Summary of operations, California oil 

fields, California Division of Oil and Gas", and in the 

"Bulletin of the American Association of Petroleum 

Geologists", particularly in reports issued since 1930. 

At Santa Fe Springs,34 for example, the Repetto, has a 

thickness of about 4,000 feet and consists of alternating

Holman, H. W., Ferrando, A., and Driver, H. L., Pliocene of apart of the city of 

Los Angeles (unpublished report presented before Pacific section of Society of 

Economic Paleontologists and Mineralogists, 1931).

2« Soper, E. K., and Grant, U. S., Geology and paleontology of a portion of Los 

\ngeles, Calif.: Geol. Soc. America Bull., vol. 43, pp. 1041-1068, 7 figs., 1932 [1933].

27 Edwards, E. C., op. cit., pp. 796-797.

M Gale, H. R., in Grant, U. S., IV, and Gale, H. R., Catalogue of the marine Pliocene and Pleistocene Mollusca of California: San Diego Soc. Nat. History M:em., 

vol. 1, p. 40, .1931.

'9 Grant, U. S., in Soper, E. K., and Grant, U. S., op. cit., pp. 1056-1058.

3° Moody, C. L., Fauna of the Fernando of Los Angeles: California Univ., Dept. 

Geology, Bull., vol. 10, pp. 39-62, pis. 1-2, 1916.

3 > Grant, TJ. S.. in Soper, E.K., and Grant, U. S., op. cit., pp. 1059-1064.

32 Hoots, H. W., Oil development in the Los Angeles Basin: 16th Internat. Geol. 

Coug. Guidebook 15, pp. 26-30, pis. 6-8, 1932.

'3 Hoots, H. W., and Herold, S. C., Natural-gas resources of California: Geology of 

natural gas, pp. 172-220, figs. 19-36, Tulsa, 1935.

Trask, P. D., Results of the American Petroleum Institute research project on 

environment of source sediments: Am. Petroleum Inst. Proc., vol. 14, sec. 4, Production Bull, 211, p. 24, figs. 6, 7, 1933.
LOWEK PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

units of sand, sandy shale, and clay shale, ranging in 

thickness from a fraction of an inch to 100 feet. Similar 

alternating units are found in other fields. Sand is 

apparently more abundant on at least some of the anticlines than in the intervening synclines,35 suggesting that 

the anticlines were growing ridges on the floor of the 

Kepetto sea. In several fields the underlying Miocene 

has been penetrated. Micropaleontologists recognize a 

transition zone between the Repetto and the Miocene. 

The contact between the Pliocene and Miocene in the 

basin appears to be gradational.

A wealth of data on the subsurface Repetto has been 

accumulated by the geologic staffs of many oil companies data on the character, thickness, and fluid content of the sediments and on the composition and stratigraphic relations of the many foraminiferal zones and 

subzones that are recognized and have stood the test of 

exacting oil-field correlations. As the immediate economic interest of these data diminishes it is hoped that 

they will be put on record, for they represent more detailed information than is available for any other area 

of comparable size in California.

LARGER FOSSILS FROM REPETTO FORMATION

OUTCROP LOCALITIES

Homer Hamlin was in Los Angeles when the Third 

Street tunnel was excavated and sent to the National 

Museum fossils collected during the excavation. The 

first lot of fossils, apparently consisting only of the 

specimens Dall described as. Lima hamlini, was forwarded to "Washington in 1900. Most of the material 

was collected in January 1901, and Hamlin used Geological Survey field labels that have a notebook citation. 

At the time when the tunnel was excavated Hamlin was 

an assistant city engineer. According to a written 

communication from Mrs. Carrie D. Hamlin, of Los 

Angeles, his geologic observations were made apart 

from his official duties. Mrs. Hamlin kindly forwarded 

a notebook containing many carefully recorded observations on the geology of the city, made during the period from April to August 1900. The Third Street 

tunnel is mentioned, but the notes on the fossil collections probably were made at a later date. Among 

Dall's papers is a letter from Hamlin to T. W. Stanton, 

dated January 24, 1901, transmitting the fossils, a 

geologic map, and a description of the geology of the 

city. This material is valuable, but it does not include 

.a detailed description of the geology of the tunnel, and 

fossil localities in the tunnel are not recorded. Therefore, it is not known from what part of the tunnel the 

fossils were collected. According to the maps accompanying the reports of Holman, Ferrando, and Driver 

and of Soper and Grant, the Miocene-Pliocene contact 

is close to the intersection of Third and Figueroa

35 Trask, P. D., Proportion of organic matter converted into oil in Santa Fe Springs 

oil field, California: Am. Asspc. Petroleum Geologists Bull., vol. 20, pp. 249-250,1936.

Streets, two blocks northwest of the northwest portal of 

the tunnel, but at that locality the contact is concealed 

by alluvium. These maps also show that the upper part 

of the Repetto formation was penetrated in the tunnel. 

Most of the fossils in Hamlin's collections have a characteristic preservation and a matrix of gray foraminiferal siltstone. Samples of this matrix from specimens 

in the second lot of Lima hamlini were forwarded to 

Wissler and Driver, who report that they carry wellpreserved Repetto Foraminifera. It is hoped that 

these micropaleontologists will put on record, their 

appraisal of the age relations of these Foraminifera. 

Whatever the age relations are in terms of the foraminiferal zones in the basin, Lima hamlini from the tunnel 

is preserved in a matrix carrying characteristic Repetto 

Foraminifera, and it is assumed that other specimens 

with similar preservation and matrix were collected 

from the Repetto.

Hamlin's collections were used for the description of 

a number of new species. Several mollusks Lima 

hamlini,36 a supposed rudistid ("Radiolites" hamlini) 37 

Priene oregonensis Redfield var. angelensis,38 and Nassa 

hamlini 39 were described by Dall, Stearns, and Arnold. 

A flightless auk, the first fossil bird to be described from 

California (Mancalla californiensis) was described by 

Lucas; 40 and a fiddler crab (Uca hamlini) by Rathbun. 41 

Arnold published a list of the fossils in 1907,42 and essentially the same list was issued in another report in the 

same year.43

Only the mollusks that have a matrix of gray' foraminiferal siltstone are accepted as undoubtedly from 

the Repetto. The following species listed by Arnold, 

which lack this matrix and have a different preservation, 

are rejected:

Fossils in Third Street tunnel collection, identified by Arnold, 

rejected as doubtful Repetto fossils

Pecten latiauritus Conrad. (Incomplete left (?) valve showing

some color markings. A little matrix remaining consists of

silty sand.) 

Pecten opuntia Dall. (Small fragment stained with ferruginous

stain. A little matrix remaining is ferruginous.) 

Pecten stearnsii Dall. (Small fragment stained with ferruginous

stain. A little matrix remaining consists of ferruginous silty

sand.) 

Fissuridea murina Carpenter. (Figured by Arnold. Virtually

complete specimen stained with ferruginous stain.)

38 Dall, W. H.. A new species of Lima: Nautilus, vol. 14, pp. 15-16, 1900.

37 Stearns, R. E. C., The fossil shells of the Los Angeles tunnel clays: Science, new 

ser., vol. 12, no. 247, pp. 247-250, 1900.

38 Arnold, Ralph, New and characteristic species of fossil mollusks from the oilbearing Tertiary formations oi southern California: U. S. Nat. Mus. Proc., vol. 32, 

pp. 536-537, pi. 50, fig. 11, 1907.

so Idem, pp. 537-538, pi. 50, fig. 9.

40 Lucas, F. A., A flightless auk, Mancalla californiensis, from tho Miocene of California: U. S. Nat. Mus. Proc., vol. 24, pp. 133-134, 3 figs., 1901.

41 Rathbun, M. J., The fossil stalk-eyed Crustacea of the Pacific slope of North 

America: U. S. Nat. Mus. Bull. 138, pp. 30-31, pi. 8, fig. 1, 1926.

42 Arnold, Ralph, op. cit., p. 527. For an earlier list see Arnold, Ralph, Tertiary 

and Quaternary pectens of California: U. S. Geol. Survey Prof. Paper 47, pp. 91, 116, 

1906.

« Arnold, Ralph, in Eldridge, Q. H., and'Arnold, Ralph, The Santa Clara Valley, 

Puente Hills, and Los Angeles oil districts, southern California: U. S. Geol. Survey 

Bull. 309, p. 152, 1907.
LARGER FOSSILS FROM REPETTO FORMATION

This may appea,r to be summary treatment, particularly as it disposes of the most troublesome species 

("Pecten" latiauritus) so far as age assignment is concerned. There appears to be some doubt as to whether 

the imperfect valve is latiauritus in the restricted sense, 

as it has relatively strong grooves on the ribs near the 

ventral nmrgin. and strong riblets in the interspaces in 

the same area. Nevertheless, it apparently is a form 

of latiauritus, which is not recorded elsewhere in formations earlier than those assigned to the Pleistocene. 

These rejected specimens may have come from a layer 

or layers of different lithology within the Repetto, or 

from some other part of the section, or they may possibly have come from some other locality. These 

suppositions cannot now be tested, and so long as there 

is doubt about the specimens they are rejected. Their 

rejection, has no bearing on the interpretation of the 

environment other than the exclusion of four additional 

species of shallow-water facies.

Dall .made a shrewd estimate of the age of the fossiliferous beds as "probably Pliocene" when he described 

Lima hamlini. In the same year Stearns described a 

supposed rudistid from Hamlin's collection and claimed a 

Cretaceous age for these beds. Dall 44 quoted Vaughan's 

opinion to the effect that the specimen thought to 

be the upper valve of the supposed Radiolites is a solitary coral, probably Stephanotrochus [Stephanocyathus]. 

The supposed lower valve Dall considered problematic. 

The material representing the coral may be in the collection of fossil corals at' the National Museum, but an 

attempt to find it at the present time is not practicable. 

Similar solitary corals are found in the subsurface 

Repetto. According to a letter from Hamlin to Dall, 

dated June 14,1900, "Radiolites" was found in the Third 

Street tunnel near the top of the section and in the 

Broadway tunnel near the middle. (The strata in the 

Broadway tunnel axe now assigned to the Miocene.) 

Moody 45 quoted. Dall to the effect that the elongate 

part of the "Radiolites" is probably a barnacle a 

statement of Dall's that I am nimble to find.

It is not known whether the bird bone was associated 

with, the Repetto inollusks. There is no matrix on the 

specimen, which was available through the kindness of 

Dr. C. W. Gilmore, of the United States National 

Museum. As the bird has no direct bearing on the 

mollusks, it is retained as a Repetto fossil. Remains 

referred to this auk have recently been found in the 

Pliocene San Diego formation at San. Diego.46 The 

coral and the fiddler crab also are retained as Repetto 

fossils.

Some old collections from Los Angeles, consisting 

principally of molds of paired shells doubtfully identi44 Dull, W. H., On the true nature ol Tamiosoma: Science, new ser., vol. 15, no. 366, 

p. 7,1902; The Miocene of Astorin and Coos Day, Oregon: U. S. Qeol. Survey Prof. 

Pupor 59, p. 14J, 1909.

4 » Moody, C. L., op. cit., p. 41. This statement is repeated by Soper and Grant 

(op. cit., p. 1043) without a citation.

1° Miller, Loyo, Tho Lucas auk of California: Condor, vol. 35, pp. 34-35,1933.

fied as Phreagena lasia, may represent the Repetto 

formation. One of these collections was made by 

Stearns in 1892 at Sixth and Lucas Streets, at an altitude of 370 feet. In addition to three doubtful molds 

of Phreagena lasia, this collection includes pieces of 

coarse-grained sandstone containing molds and impressions of Calyptraea, Turritella?, Bittium?, Chione?, 

and Solenf, fragments of Ostrea, and shark teeth. According to the maps cited, the lower part of the Repetto 

formation strikes through the intersection of these 

streets. These fossils represent a shallow-water facies. 

Three recent collections made by W. H. Holman in 

Los Angeles consist of Lima hamlini, Fusitriton aff. 

F. oregonensis, a cassidulid echinoid, and cone scales of 

a pine.

Other outcrop material considered in the systematic 

account embraces specimens of Lima hamlini from 

Malaga Cove, on the west coast of the Palos Verdes 

Hills, and specimens of "Nassa" hamlini and Acila 

semirostrata from the transition zone between the 

Repetto and Pico formations in the Repetto Hills.

SUBSURFACE LOCALITIES

Hertlein's record of Pecten (Pseudamusium) vancouverensis Jernandoensis from a depth of 2,800 feet in 

a well in the Long Beach field 47 appears to be the only 

subsurface record of a Repetto larger fossil in the basin. 

The Standard and Union collections of core fossils represent 60 wells, most of which are in fields that produce 

oil from the Repetto.48 Several wildcat wells also are 

represented in these collections. Wissler identified 

Lima hamlini and Hyalopecten aff. H. randolphi tillamookensis in material from 6 additional wells that was 

not forwarded to Washington, making a total of 66 

wells, in 56 of which the fossils are determined at least 

generically. The location of the oil fields is shown on 

plates 2 and 4.

Wissler and Driver kindly verified the assignment of 

the fossils to the Repetto formation. Geologists and 

micropaleontologists who are familiar with the details 

of oil-field correlation in the basin have at their disposal 

data to determine the stratigraphic position of the 

species and to determine whether any zonal arrangement is apparent. Wissler submitted a chart showing 

the stratigraphic distribution of the larger fossils with 

reference to foraminiferal zones. These data are cited 

only in general terms. It is hoped that Wissler will 

eventually publish them. The records may be too 

scattered to work out any zonal arrangement. Molluscan zones in the Repetto are likely to be facies zones. 

Changes in facies, however, may have been controlled

47 Hertlein, L. G., New species of marine fossil Molluscs from western North 

America: Southern California Acad. Sci. Bull., vol. 24, p. 43, pi. 4, fig. 6,1925. I am 

indebted to S. G. Wissler for examining samples from wells in the area where this 

species was recorded. According to Wissler, the horizon is near the top of the Repetto 

formation.

48 See Hoots, H. W., Oil development in the Los Angeles Basin: 16th Internat. Geol. 

Gong. Guidebook 15, table opp. p. 26,1932.
8 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

by events that took place at about the same time over 

a considerable area in the basin, and any zone may 

therefore be of chronologic value.

Owing to the character of the material or to meager 

representation, many of the specimens in both outcrop 

and core collections are indefinitely identified. Some 

of the fossils, including all the material from a few wells, 

are listed as "undetermined." Much of this material is 

properly classifiable as undeterminable; some species 

could be provisionally determined if better specimens 

were available from other localities. For the most part 

the undetermined specimens are not considered in the 

descriptions of species.

The Standard collection includes material from 5 

wells assigned by Driver and Wissler to the Miocene 

and material from 9 wells assigned to the Pico formation. This material is not included in the descriptions 

of species other than to furnish records of Miocene and 

Pico occurrences of Repetto species or of forms that 

are similar to Repetto species.

FOSSILS

The outcrop and core fossils are listed in the following 

lists. To facilitate ready comparison, the names used by 

Arnold for the Third Street tunnel fossils are cited opposite the names here used for the species from that locality.

Fossils from outcrop localities of Repetto formation on borders of Los Angeles Basin

Third Street tunnel, Los Angeles

[Homer Hamlin, collector, 1900,1901. U. S. G. S. localities 3432 (1900) and 3426 (1901)]

Name used in this report Name used in this report Name used by Arnold

Coral:

Stephanocyathus? ( p r e -

sumably represented in

type material of "Radiolites" hamlini Stearns). 1

Mollusks:

(Rejected)--_--.-------__.

Astraea cf. A. gradata

Grant and Gale (figured) .

Undetermined naticid_.____

Fusitriton aff. F. oregonensis (Redfield) (figured).

"Nassa" hamlini Arnold- _ _

Plicifusus? sp. (figured) _. __ 

Buccinum? sp. (figured).. __ 

Anadara camuloensis (Osmont) (figured). 

(Rejected) ____ ____________

Coral.

Fissuridea murina

(figured). 

(Not considered.)

Carpenter

(Rejected) _____ __________

Lyropecten cerrosensis 

(Gabb) (figured).

Neverita recluziana Petit. 

Priene oregonensis Redfield

var. angelensis Arnold (type

locality). 

Nassa hamlini Arnold (type

locality).

Pleurotoma sp. undet. 

Buccinum sp. undet. 

Area multicostata Sowerby.

Pecten stearnsii Ball. 

Pecten opuntia Dall. 

Pecten latiaturitus Conrad. 

Pecten ashleyi Arnold.

Mollusks Continued.

Hyalopecten aff. H. randolphi (Dall). 

Ostrea vespertina Conrad

(figured). 

Lima hamlini Dall (type

locality; figured). 

(Not recognized)_________

Phreagena lasia Woodring,

n. gen., n. sp. (figured). 

Lucinoma aff. L. aequizonata (Stearns) (figured). 

Trachycardium cf. T.

quadragenarium (Conrad) (figured). 

Undetermined- __________

Decapod crustacean:

Ucahamlini Rathbun (type

locality). 1

Bird:

Mancalla californiensis 

Lucas (type locality). 1

Pecten pedroanus Trask (figured) . 

Ostrea veatchii Gabb.

Lima hamlini Dall.

Astarte sp. 

Carditoid.

(Not considered). 

(Not considered.)

Macoma sp. undet.

(Not mentioned. A crab claw 

is mentioned in U. S. Geol. 

Survey Prof. Paper 47, p. 91, 

1906.)

Bird bones.

1 Not known to have been associated with the Repetto mollusks.

Other outcrop localities

Fossil Locality Collector U. S. O. S. locality

Fusitriton aff. F. oregonensis (Redfield).

Pinus cf. P. muricata D. Don (cone 

scales).

Lima hamlini Dall__________________.

Cassidulid echinoid_ _________________

Lima hamlini Dall.

Lima hamlini Dall.

(

100 feet northeast and 90 feet northwest 

from, northeast corner Second and Hill 

Sts., Los Angeles; about 4 feet above 

level of Hill St.

10 feet northwest from preceding locality.. 

North side of Wilshire Blvd., 200 feet east

from center line of Bixel St. 

Malaga Cove, west coast of Palos Verdes 

HiDs, north limb of northern syncline 

near trough; 5 to 10 feet below lower bed 

of volcanic ash in Repetto formation. 

Same locality, north limb of syncline just 

north of trough; not more than 10 feet 

below lower bed of volcanic ash.

>W. H. Holman.

_do_

W. P. Woodring.

S. G. Wissler _

13862.

13862a. 

13923.

13838.

(Collection of Union 

Oil Co.)
LARGER FOSSILS FROM REPETTO FORMATION

Fossils from subsurface localities of Repetto formation in Los Angeles Basin

9

Fossil

"(Dull) (figured).

2 undetermined pelecypods, 1 of

which evidently is a small 

rnactrid. 

Soleinya afT. S. johnsoni Dall 

(figured) .

Phreagena lasia Wopdri:ng, n. gen., 

n. sp. (figured hofotype).

ring?, n. var.

(Eedfield). 

Undetermined pelecypod, possibly

a small lucinid. 

Undetermined pelecypod, possibly

a small oyster.

n. sp.

I-Mi vf*n urfMi n 1 n QI n \V fir^fli*! n ff T\ 0*0 71

n. sp.

(Redfield). 

Phreagena lasia Woodring?, n. 

gen., n. sp.

Calyptogena n. sp?_. ____ 

(Montagu)" (figured). 

Fusitriton afT. F. oregonensis

(.Redfield). 

Macrocallista sp ______ 

Gale (figured).

small gastropods and pelecypods.

(.Redfield).

Thracia. 

Fusitriton afT. F. oregonensis

(Redfield).

(Redfield).

Lima hamlini Dall _._.__________-

gen., n. sp. 

Undetermined small pelecypod.. __

Limopsis phr-ear Woodring, n. sp._

a small Limopsis. 

Lima hamlini Dall___ - _

Undetermined ech'inoid spines. .__

(Dall). 

Lima hamlini Dall_____ _-____-

Lima hamlini Dall.____-.__ ____

"Nassa" hamlini Arnold. ________

(figured). 

Limopsis phrear Woodring, n. sp__

(figured).

Locality

Montebello field .

 do .

1_.__ do 

 .do _

... do -

... __do . 

... __do .

. ....do. --------

_____ do 

... ..do ..

1 .do 

 ._ .do 

 ...do. --------

Puente Hills,

sec. 30, T. 2 

S.,R. 10W.

[East Coyote

[ field. 

West Coyote

field. 

_ .do 

.....do . 

.....do..-- .

__. do 

 ..do ..

... ._ do . 

. _.do. --------

....'.do.. .

 .do .

-_-.-do--------

.... ..do. .-_---_-

 .do... ... .

__ ... do. .

.... .do 

.... .do 

__ ... do... -

._ .. .do.. .

}....do .

Santa Fe Springs

field. 

- do 

 do 

. do 

---..do--------

Culver City _ __

Inglewood field. _

Company

Standard _______

 do. .

_---.do. -------

-__-_do_. ______

__--_do_-___-___

_--..do- ------

 do 

 .do.. ------

_--,_do--------

_-_._do-___-___-

... ._ do. --------

. _do._ _ 

_. ...do ..

Universal Consolidated.

Great American

Standard . 

..... do.. ....

 __do __

_.. -.do. ________

-__--do_--_-_-_-

___-.do__-----_-

_---_do_--_---_-

.....do ... ...

_____ do--_____-

 _._ do. --------

... ..do 

 ..do.. 

__ _do_--____-_

... ..do __-

.... .do 

... ._ do.... .

_... .do ..

___-_do .

 __ .do .

_----do__----__-

___-_do__.____-_

._ do _. ._

_-_-_do__-i-__._

Taylor. _.____._

Lease

-_--.do. ... ...

 .. .do... ...

.....do.- .

 ..do.- .. .

... ..do ..._-_

- .do... ......

-_--_do_-_-_____-

TempJe. ________

 ..do ... ...

... ..do... .. __

 .do 

Nutt ._.-_-.

TufTree...---.-..

Murphy Coyote. _

.----do-__-----_-

-----do-_---__.__

_---_do----___-_

Emery.-. ____ _

 .do 

. .do... .....__

_.. do.. __ __ _.

---_-do_-_____.__

--...do---------

.-___do. _-___-_-_

___-.do_-____-___

_---_do-_----___

 do 

__ .do... _

--_.do.---_. _

. .do ...

... .'.do _-_

Bastanchury

ranch.

Bell... .._...__..

-----do_--._--_-.

__ do ...

 do _

Uharriet. _ ___ _

Well

41

7?,

7?,

73

73

74

75

75

77

IS

19

19

19

?,

11

?,

113

117

117

m

50

52

52

52

52

52

53

53

54

54

5fi

57

59

59

1

43

45

53

69

17

1

105

Depth (feet)

3,600

1, 926

3, 750

3, 340-3, 358

4, 745

1, 955-1, 975

1, 740-1, 750

6, 015

4,500

3,044

1,265

4, 811-4, 825

4, 966-4, 986

3, 627-3, 655

818

3, 351-3, 356

4, 450

4,400

5,910

4, 255-4, 273

5, 105

3, 625-3, 626

3,640

3,653

3,663

3,695

4,273

6 194

4,230

5, 90.0

4, 341-4, 347

5, 265

4, 270

4,304

6 J 414

5, 518

5, 564

6,237

3, 642

5, 631

3, 221

2,221

U. S. O. S. locality

13907.

13863.

13863a.

13864.

13864a.

13865.

13866.

13866a..

13867.

13868.

13869.

13869a.

13869b.

13871.

ion Oil Co.)

13873.

13874.

13875.

13875a.

13876.

13877.

13878.

1387Sa.

13878b.

13878c.

13878d.

13879.

13S79a.

13880.

13880a.

13881.

13882.

13883.

13883a.

13884.

1401 9

ion Oil Co.) 

Do.

Do.

13885.

13887.

1 3son
10 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Fossils from subsurface localities of Repetto formation in Los Angeles Basin Continued

Fossil

(figured) .

ently a neptuneid.

(Redfield) (figured).

(figured paratype).

Lunatia.

Malletia.

sp. (figured).

sp. (figured holotype).

ring, n. var. (figured holotype).

"Nassa."

(figured holotype).

mookensis (Arnold) (figured). 

Sponge of family Farreidae, probHyalopecten aff. H. randolphi tillamookensis (Arnold).

lamookensis (Arnold).

possibly a lucinid.

(figured) .

Malletia.

(Carpenter) (figured).

Gale) (figured).

Locality

_ __ do_--_-__ _

_..__do __ ....

___._do_-___.___

_____do-_______

 do 

..... do 

 do 

.....do.. _._._..

_.___do_-_-_.__.

----.do.----__._

.....do.........

.....do.........

__--_do-_______

__-__do_.___.__.

_____do- _ _____

-____do--_--___

____.do_--._ _ _

Seal Beach field.

Huntington

Beach field. 

_-___do.-_-_____

__ _ do.________

_-___do-_-_____

1 .do __

_____do_________

Monica, sec. 9, 

T. 2 S., R. 15 

W. 

Playa del Rey

field. 

_____do_--_-____

.....do ._._.__

_____do_________

El Segundo field.

Lawndale field, 

sec. 10, T. 3 

S., R. 14 W.

Lawndale 

field, sec. 22, 

T. 3 S., R. 14 

W.

f"PnT*t* J n /*»P fiplH

Company

Standard- _

Pacific Western.

Western Consolidated. 

Barnsdall __ _ _ .

Union _ _____

 .do -

 do 

 .do 

 .do 

 do 

.....do ... 

 .do 

 ..do 

_---_do____-__-_

ShelL_ _._.__.

 .do 

 do 

 do__ -------

Standard. _-___

_ --do.__-_____

 do 

 do..... _ -

Julian.. ________

 do 

Huntington Signal. 

Hines____ __

Ohio.... _ ._ .

_____do___-_____

A. T. Jergins

Trust. 

Mohawk __ ___

Republic. ______

Signal Finance _ .

Shell.-.. _---__

Standard-------

field Midway.

minal.

Lease

Baldwin-Cienga. _

Cone __ __ __ _

Smith.. ___ _ _

Trust ____ __

Rosecrans _______

Callender _ _______

 ..do..... .....

-. .do. ________

Hellman____

 ..do.... ------

 do 

 ..do... ____.--

-----do....-._...

----_do_____-___.

_-___do _ _.__-_

 .do......_...

Reyes-__ ____

 do.. --------

.....do... __ --.

 ...do..........

San Gabriel._____

Bolsa___ _--_-__

. _ _do_ _ .---.-

 __do___ ___ _

Farnsworth. _ _ _ _

-----do__________

Hand . _ ._

Happy Days__ _

Recreation. _ ___

Del Rey. _ ___.

Robertson__ ____

J... __.___.

El Segundo _ __

Woods. _________

Barkdall _______

Bodger___--_____

Well

105

16

1

1

15

17

22

?7

10

14

14

17

17

IS

19

19

43

43

43

101

25

7

32

38

2

2

2

1

1

2

1

1

1

1

1

1

71

1

Depth (feet)

5, 713

2, 926-2, 945

3,941

5, 760

5,686

5,463

4,146

4, 998

4, 193

4,505

5,102

3, 939

4,216

4,076

3, 940

4, 292

4, 135

4,841

5,128

5,245

4, 929

3, 720

3,466

3, 874-3, 894

2,081

2, 135

3,454

6,517

3, 821

4,001

3,830

3,848

4,421

5, 100

5,346

5,398

3,245

3,265

U. S. Q. S. locality

13890a.

13892.

13924.

(Collection of Union Oil Co.) 

14013.

(Collection of Union Oil Co.) 

13895.

13896.

(Collection of Union Oil Co.) 

Do.

13897.

13898.

(Collection of Union Oil Co.) 

13899.

(Collection of Union Oil Co.) 

Do.

14014.

(Collection of Union Oil Co.) 

Do.

13900.

13901.

13904.

13906.

13974.

13908.

13908a.

13909.

(Collection of Union Oil Co.) 

Do.

14015.

13911,

(Collection of Union Oil Co.) 

13914.

(Collection of Union Oil Co.) 

Do.

14002.

13915.

13916.
LARGER FOSSILS FROM REPETTO FORMATION 11

The following table, in which the undetermined mollusks are omitted, summarizes the occurrence of the 

fossils and the occurrence of single-valve and paired specimens of pelecypods:

Larger fossils from Repetto formation of Los Angeles Basin 

[S, Single-valve pelecypods; P, paired (double-valve) pelecypods; X, occurrence of fossils other than pelecypods]

Species

Sponge (identification by M. W. de Laubenfels):

Coral identification by J. E. Hoffmeister) :

Gastropods: 

Astrea cf. A. gradata Grant and Gale (pi. 5, 

fig. 17)______________--_-_-__._____-------

Fusitriton aff. F. oregonensis (Redfield) (pi. 5, 

figs. 21-23) ---__-_--------_-----------_

"Nassa" hamlini -Arnold (pi. 5, fig. 16)__ __-_..

Pelecypods:

Acila semirostrata (Grant and Gale) (pi. 5, figs. 

10, 11).. ................................

Anadara camuloensis (Osmont) (pi. 6, figs. 10, 

13-16) --------- ----. ----------

Limopsis phrear Woodring, n. sp. (pi. 5, figs. 

7-9, 12, 13)_. .__.._-.-_-_-. ______________

Lyropecten cerrosen'sis (Gabb) (pi. 7) __________

Hyalopecten aff. H. randolphi (Ball) (pi. 6, 

'fig. 7)__ ____ _ _______ __..__._-. _ _.

Hyalopecten aff. H. randolphi tillamookensis 

(Arnold) (pi. 6, fig. 3). ____________ _.___.__

Ostrea vespertina Conrad (pi. 9, fig. 5) _________

Lima hamlini Dall (pi. 8, figs. 5, 7, 10, 11)_____

Limatula aif. L. "subauriculata (Montagu)" 

(pi. 8, fig. 6)..- -- _______________

Phre'agena lasia Woodring, n. gen., n. sp. (pi. 5, 

figs.. 3, 4)

Calyptogena n. sp. (pi. 5, figs. 5, 6) ___________

Lucinorna afF. L. aequizonata (Stearns) (pi. 5, 

fig. 1). __________________________________

Trachycardium cf. T. quadragenarium (Conrad) 

(pi: 9, fig. 1)_______._____________________

Katherinella aff. K. subdiaphana (Carpenter) 

(pi. 6, fig. 12)______________________-_.___

Macrocal] ista sp_________________-----__-___

Corbula gibbiformis Grant and Gale (pi. 6, 

figs. 8, 9)___----___-__--_--_.___. ________

Periploma cryphia Woodring, n. sp. (pi. 9, 

figs. 4, 6)______-_________________._______

Periploma cryphia stenopa Woodring, n. var. 

(pi. 9, fig. 7). ____________________________

Echinoids (identifications by Th. Mortensen and 

A. H. Clark): 

Araeosoma sp. (pi. 9, figs. 2, 3) _______________

Cassidulid _________________________________

Decapod crustaceans (identifications by M. J. 

Rathbun): 

Uca hamlini Rathbun_ ______________________

Callianassa sp ______________________________

Astacus? sp-_______-_--___-______-____-_.__

Plants (identifications by R. W. Brown): 

Pinus cf. P. muricata D. Don (cone scales) _____

Undeterminable leaves. _ _ __________________

Bird: 

Mancalla calif orniensis Lucas _ ______________

Outcrop

Angeles Los 

X

y

x

x

X

s

s

s

R

P

P

S

R

X

X

X

X

Hills Verdes Palos

S

Subsurface

Montebello field

X

P

s

8

P

?s

?R

X

Hills Puente 

X

field East Coyoe 

R

R

field West Coyote 

X

X

R

S

?R

R

X

X

X

field Springs Santa Fe

X

R

R

S

City Culver Near

S

Inglewood field

X

S

s

Rosecrans field

P

Dominguez field

X

P

S

s

8

Seal Beachfield

S

Huntington Beach field

X

X

R

R

S

Playa field del Key 

S

s

El Segundo field

x

Northeast ofLawndale field

R

field Lawndale 

S

of Lawndale field Southeast 

P

field Torrance 

R

Wilmington field

S
12 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

INFERRED ENVIRONMENT OF LARGER FOSSILS

This discussion of the environment and paleogeographic implications of the larger fossils of the Repetto 

formation rests on the basic assumption that the 

Repetto animals represent essentially the same environment as modern animals to which the fossils are closely 

allied by the similarity of the parts preserved as fossils. 

This assumption, which is habitually made by paleontologists, has been casually noticed,49 but no analysis 

of it has come to my attention, and it may not be worth 

an elaborate analysis. The principle that stability in 

physiologic (biochemical and biophysical) characters is 

correlated with stability in morphologic characters and 

that evolution in the two sets of characters keeps close 

pace is implied in the assumption. The physiologic 

characters of many marine animals are still unknown, 

except so far as they are reflected in their distribution 

and habits. Inasmuch as there is a general but not 

invariable correlation between affinity determined by 

selected morphologic characters the criterion most 

frequently used by zoologists and the one perforce used 

by paleontologists and affinity determined by physiologic characters in the forms that have been considered,50 the assumption may not be justified. Other 

things being equal, the validity of the assumption probably varies inversely with the duration of time involved 

that is, in general terms it is more probable that the 

assumption is justified in dealing with Pleistocene animals that are indistinguishable from modern ones on 

the basis of selected morphologic characters, or are 

closely allied to them on this basis, than in dealing with 

Pliocene or earlier fossils. The probable validity of the 

assumption for the Repetto fossils is considered from 

another point of view in the discussion of the number 

of Repetto fossils that indicate a particular environment and their distribution at other localities in 

California where marine Pliocene formations are found. 

(See p. 15.)

DEPTH RANGE OF ALLIED MODERN SPECIES

The depth range of modern Pacific coast mollusks 

and echinoids that are considered closely allied to 

Repetto fossils is graphically shown on plate 3. In the 

preparation of the graphs only the species whose 

affinity is regarded as reasonably close or those representing genera the modern species of which have an 

invariable shallow-water (Ostrea, Trachycardium, Macrocallista') or deep-water (Araeosoma) habitat, were 

used. The data are drawn from the collections of the 

United States National Museum, which include the 

dredgings of the United States Fish Commission

« Eobson, O. C., The species problem, pp. 103-104, London, 1928. Woodring, 

W. P., Fossils from the marine Pleistocene terraces of the San Pedro Hills, California: Am. Jour. Sci., 5th ser., vol. 29, no. 171, p. 300, 1935. Broch, Hjalmar, Some 

zoogeographical problems of the northern Pacific: Science, new ser., vol. 83, no. 2144, 

p. 102, 1936. Doubtless other workers have considered this assumption, but I have 

not attempted to pursue the matter.

M Robson, Q. C., op. cit., pp. 53-88.

steamer Albatross, The dredgings of the Albatross are 

the only ones now available from deep water in the 

eastern Pacific. The depth divisions on plate 3 are 

units of 100 fathoms. The width of a graph at the 

midpoint between depth division lines represents the 

percentage of dredging records for that species within 

the depth unit. The figures in the vertical columns 

represent the total number of hauls, and the number of 

additional lots that have no depth data are added in 

parentheses. These lots without depth data probably 

represent material from shallow water. As the graphs 

are not weighted for the number of hauls, the figures 

should be kept in mind in comparing the graphs. Many 

of these modern mollusks have not yet been adequately 

studied, and some of them may represent a group of 

closely allied forms rather than one form. This distinction should have no essential effect on the interpretation of the Repetto fossils under the assumption 

specified. For the purpose of this discussion shallowwater species are defined as those ranging from the 

intertidal zone to 100 fathoms; deep-water species as 

those ranging from 100 to 2,000 fa thorns; and abyssal 

species as those below 2,000 fathoms. The faunal 

regions are those recognized by Bartsch,51 most of 

whose names are altered so as to have terminations 

that seem to be more euphonious. The regions and 

their limits are as follows:

Faunal regions on Pacific coast of North America and Central

America

[After Bartsch]

Arctic. From summer limit of pack ice southward to winter 

limit that is, from Sea-Horse Islands south to Hagemeister 

Island. (Not represented.)

Aleutian. Aleutian Islands and southeast to Sitka.

Oregonian. Sitka, Alaska, south to Point Conception, California.

Californian. Point Conception, California, to Cape St. Lucas, 

Lower California.

Mazatlanian. Gulf of California south to Acajutla, Guatemala.

Panamanian. Acajutla, Guatemala, south probably to Aguja 

Point, Peru.

This arrangement has recently been criticized 52 and 

doubtless can be improved, but it is sufficient for this 

discussion, as it has no essential bearing on the interpretation.

On the basis of depth range these modern species 

fall into three groups, arranged from left to right in the 

graphs (1) shallow-water species; (2) species ranging 

from shallow water into deep water; (3) deep-water 

species. Increase in depth with decrease in latitude is 

shown in the graphs of species, or groups of forms, that 

range through more than one faunal region, particularly 

in the graphs of Hyalopecten randolphi tillamookensis, 

H. randolphi, and Solemya.

51 Bartsch, Paul, Ocean currents, the prime factor in the distribution of the marine 

mollusks on the west coast of America: Bernice P. Bishop Mus. Special Pub. 7, p. 

507, 1921.

M Schenck, H. O., and Keen, A. M., Marine molluscaa provinces of western 

North America: Am. Philos. Soc. Proc., vol. 76, pp. 921-938, 6 flgs., 1936.
INFERRED ENVIRONMENT OF LARGER FOSSILS 13

Dredging records for many of the species are inadequate. The irregularity in the upper depth limit of 

Solemya is probably due to inadequate records in the 

Oregonian and Mazatlanian regions. Gaps in the 

graphs presumably would be filled by additional dredgings, unless the isolated graphs in each column represent 

different forms, which is improbable for most of the 

columns. It is doubtful, however, whether the range 

of the deep-water species will be moved upward into 

shallow water by additional records, for much more is 

known about the distribution in shallow water than 

in deep water. The single record of -Fusitriton 

oregonensis in the Californian province at a depth of 

1,081 to 1,100 fathoms surely is not an adequate 

representation of the depth distribution in this province, 

as is indicated, by the steep depth gradient between the 

Oregonian and Californian provinces. It is improbable 

that oregonensis occurs in shallow water in the Californian province, but it may now live there at depths 

considerably less than 1,081 fathoms, and during 

Pliocene and Pleistocene time it may have lived in this 

region at depths of less than 100 fathoms. It is 

recorded from Pliocene deposits in the Eel River Basin, 

San Francisco Bay region, Santa Maria Basin, Ventura 

Basin, and Los Angeles Basin. Its associates afford 

grounds for doubting whether it represents depths 

greater than 100 fathoms at most of these localities. 

If it lived only at depths greater than 100 fathoms off 

the coast of California during Pleistocene time, my 

suggestion that its presence at one locality in the Palos 

Verdes sand of the Palos Verdes Hills is due to storm 

transportation from an offshore habitat 53 is erroneous. 

The Repetto representative of oregonensis is placed in 

the group of fossils of intermediate depth range inferred 

to represent a range from shallow water into deep water.

The condition of many of the deep-water specimens 

leaves .no room for reasonable doubt that they lived at 

the depth where they were dredged. Most specimens 

of the two forms of Hyalopecten consist of paired shells, 

in some of which the dried soft parts are distinguishable 

through, the thin translucent shell. Many of the 

specimens of Solemya johnsoni are paired shells on 

which the long, thin periostracurn is virtually intact. 

Both species of Limopsis are represented, by many 

paired shells that have an intact periostracum.

INFERRED DEPTH RANGE OF LARGER FOSSILS

The larger fossils are classified in three depth-facies 

groups corresponding to the three groups of analogous 

modern species.

Shallow-water fades. Modern allies of five Repetto 

species are restricted to shallow water. For the most

«» Woodring, AV. P., op. clt. (Am. Jour. Sci., 5th ser., vol. 29), pp. 303-304. When 

the account of the torraco fossils was written a small imperfect specimen from a depth 

of 63 fathoms oil Sauta Hosa Island (U. S. Nat. Mus. No. 211299), evidently a Barburofusus, thon arranged under Fusitriton oregonensis in the collections of the U. S. 

National Museum, was accepted as oregonensis without examination.

part the modern species represent depths of only a few 

fathoms. Species similar to Lyropecten cerrosensis and 

Corbula gibbiformis appear to be extinct in the eastern 

Pacific. From the facies at other Pliocene localities 

where these two species are found, it is inferred that 

they belong in the group of fossils of shallow-water 

facies. A fiddler crab ( Uca hamlini} and a mud shrimp 

(Callianassa) also are placed in this group.

Intermediate-depth jades. The fossils of intermediate-depth facies embrace species that are inferred to 

represent a range from shallow water into deep water. 

In addition to three species whose modern analogs are 

shown on plate 3, two others (Lunatia cf. L. caurina, 

and Acila? cf. A. castrensis) are placed in this group. 

The affinities of these two forms are uncertain, but 

probably they are allied to the modern species with 

which they are compared. Suites of shells from the 

California coast arranged under Lunatia caurina at 

the National Museum have a depth range of 68 to 822 

fathoms. Acila castrensis is represented in. the same 

region by suites having depth records of 16 to 233 

fathoms.

Deep-water fades. The fossils of deep-water facies 

are the most interesting. This group embraces the 

seven species whose modern analogs are shown on plate 

3. The sponge from the Himtmgtoii Beach field is an 

additional representative of this group. The sponge 

remains were identified by De Laubenfels as belonging 

in the family Farreidae and almost certainly in the 

genus Farrea. De Laubenfels pointed out in a written 

communication that this sponge represents a deep-water 

type and that a species of Farrea was dredged by the 

Albatross off San Diego at a depth of 359 fathoms. 54 

Other species of Farrea were dredged at depths of 685 

fathoms off Washington and Lower California. 55 

Additional fossils of deep-water facies may be represented by the coral Stephanocyathus? and by the mollusks Plicifusus?, Bucdnum?, and Periploma cryphia. 

The coral without much doubt belongs in the deep-water 

group, but the preservation is too poor for certain identification. Plicifusus? sp. and Bucdnum? sp. appear 

to be shells of northern aspect and therefore probably 

of deep-water facies. At all events they apparently 

are not similar to shallow-water forms living in this 

region nor to Pliocene fossils from other localities in 

southern California. Periploma crypliia has no known 

modern analog in the eastern Pacific but appears to resemble most closely modern deep-water species from 

other areas.

Lima hamlini and Limopsis phrear are the most wide- , 

spread .of the fossils of deep-water facies. Lima hamlini 

is closely allied to L. agassizii, known from only one 

specimen dredged in the Panamanian region at a depth 

of 322 fathoms. Both species belong to a group of

81 Schulze, F. E., Amerikanische Hexactinelliden nach dem Materiale der Albatnm-Expedition, pp. 71-72, Jena, 1899. 

" Idem, pp. 68-71.
14 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

giant thin-shelled Limas of the subgenus Acesta that 

has a wide distribution in deep water, as shown in the

following table, which summarizes the data for the 

modern species:

Dredging records of giant deep-water Limas of the subgen'us Acesta

Species

agassizii Ball 5 __________________.__-

Locality

fNorway___________ ________ _______

Southern Chile ______ ________________

Gulf of Panama. _ _________________

Philippine Islands __________________

Philippine Islands. __________________

Celebes. _ __________ ______________

-__-.do-__-_-_____. --__---__--____-_

Eastern Arabian Sea______ __________

Depth (fathoms)

2 150-300

3 150-1, 450

f 258 

< 348

[ 449 

322

<> 775

( 280 

281

{ 432

505

I ' 508 

190

f 83(?)

161 

175 

182

186

209 

220 

I 226 

519

559

305

430

Bottom 

temperature (degrees Fahrenheit)

47.9 

49. 9

46. 9 

46

46.8

53. 5

49.8

57. 4 

54.3 

54. 3

52. 4 

53. 9 

53. 3

39. 2

43. 2

Character of bottom

Blue mud. 

Do.

Do.

Dark-gray sand.

Gray mud, coral sand.

Fine coral sand. 

Globigerina. 

Globigerina, sand.

Soft green mud. 

Green mud. 

Do. 

Do.

Do.

Do.

1 There is no dredging record for niasensis Thiele, 1918, from Nias. L. diomedae Dall, 1908 (Galapagos, 385 fathoms), and verdensis Bartsch, 1913 (Philippines, 394 fathoms), 

apparently do not belong to this group of thin-shelled species, and it appears to be doubtful whether smithi Sowerby, 1888 (Japan), does.

2 Dall, W. H., Notes on the giant Limas: Nautilus, vol. 16, p. 16, 1902. 

' Thiele, J., Familia Limidae: Systematisches Conchylien-Cabinet, vol. 7, pt. 2a, p. 20, 1918.

< Dall, W. H., The Mollusca and the Brachiopoda [Albatross Kept.]: Harvard College Mus. Comp. Zoology Bull., vol. 43, p. 407, 1908. A specimen (U. S. Nat. Mus. 

95987), not mentioned by Dall, was dredged at a depth of 258 fathoms. 

« Dall, W. H., idem.

 Dall, W. H., op. cit. (1902), p. 16.

7 L. smithi Bartsch, Paul, The giant species of the molluscan genus Lima obtained in Philippine and adjacent waters: U. S. Nat. Mus. Proc., vol. 45, pp. 236-237, 1913. 

Thiele, J., op. cit., p. 24; L. bartschi n. name for L. smithi Bartsch, 1913, not Sowerby, 1888. Bartsch, Paul, Nautilus, vol. 37, pp. 69-70,1923; L. hughi n. name for L. smithi 

Bartsch, 1913, not Sowerby [1888].

<> Bartsch, Paul, op. cit. (1913), p. 237. The label reads 338 fathoms.

o Idem, pp. 237-239.

10 Idem, p. 240.

11 Idem, p. 240. The only specimen is a very small, presumably young specimen. The temperature record is taken from the label.

12 Idem, p. 239. The only specimen is a small, presumably young specimen that may need comparison with young shells of rathbuni of the same size, which are not 

available.

3 Smith, E., A., On Mollusca from the Bay of Bengal and the Arabian Sea: Annals and Mag. Nat. History, 7th ser., vol. 4, p. 251,1899.

Limopsis phrear is closely allied to the modern 

Panamanian L. dalli, whjch is represented in the 

Albatross collections by 8 lots that have the remarkable 

depth distribution of 1,067 to 2,232 fathoms the latter 

the greatest depth at which the Albatross dredged in 

the eastern Pacific. This Repetto species is also allied

to L. zonalis, which has a range in the same region of 

546 to 782 fathoms and was differentiated from L. dalli 

principally on the basis of characters not available in 

fossils. Dredging records for the species of Limopsis 

allied to L. phrear are presented in the table below as 

follows:

Dredging records of species of Limopsis allied to L. phrear

Species

jousseaumi Mabille and Rochebrune.-

Locality

(

Gulf of Panama. __ ____________

Chile. _________________________

Depth 

(fathoms)

( 1, 067 

1, 132 

1, 175 

{ 1,471

1,672 

1,793

I 1,823 

2,232

f 546 

J 555

1 OOD

[ 782 

/ 369

^ i &&

Bottom temperature 

(degrees 

Fahrenheit)

37 

36.3 

36.8 

36.6

36. 4 

35.8

36. 4 

35.8

40. 1 

40.2

CO

38. 5 

46. 9

47.9

Character of bottom

Yellow Globigerina ooze. 

Gray Globigerina ooze. 

Green mud, sand, rock. 

Green ooze.

Fine black and green sand. 

Green mud.

Green ooze. 

Green mud.

Soft black mud. 

Green sand.

Sand. 

Green sand. 

Green mud.

' Data from Dall, W. H., The Mollusca and the Brachiopoda ''[Albatross Rept.]: Harvard College Mus. Comp. Zoology Bull., vol. 43, pp. 393-395,1908. Character 

of bottom from Townsend, C. H., Dredging and other records of the U. S. Fish Commission steamer Albatross: U. S. Fish Comm. Rept. for 1900, pp. 387-562, pis. 1-7,1901.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 180 PLATE 3

ANAOARA TRACKYCAH-<KACRCCA-L-' ASTRAEA

MULT]COS-piUM OUADR/H .'STA 1 UNOOS 

TATA I SEMARIUM

SOLEMYA JOHNSON!; SOLEMYA AGASSI Z!

Ca'ifcrrtlar: 

Ga'ifomrar: rCaJifornian! Paria.T.atia- Ca!iforr::an rlar Ca^fa.-r.-a-vQreorra." Ca'rfcrrian Aleutian ; 0regoman Galtforrv.an Aleutian Oregonian Californian A'eut:an Cregorvar :an Califcrniart'Xazat'anfanifanatr.ar'.fa

Modern species

Ostrea spp_______________________

Anadara multicostata_____________

Trachycardium quadragenarium. _ _.

Macrocallista spp_ _______

Astraea undosa._________

Katheritaella subdiaphana.

Limatula "subauriculata". 

Fusitriton oregonensis____

Hyalopecten randolphi tillamookensis. 

Lucinoma aequizonata_____________

Hyalopecten randolphi.

Lima agassizii.__________-_---_---

Araeosomaeurypatuin; A. leptaleum. 

Solemya johnsoni; S. agassizi______.

Limopsis dalli; L. zonalis_____--___-

Analogous Repetto fossils

Ostrea vespertina.

Anadara camuloensis.

Trachycardium cf. T. 

quadragenarium.

Macrocallista sp.

Astraea cf. A. gradata.

Katherinella aff. K. subdiaphana.

Limatula aff. L. "subauriculata."

Fusitriton aff. F. oregonensis.

Hyalopecten aff. H. randolphi tillamookensis.

Lucinoma aff. L. aequizonata.

Hyalopecten aff. H. randolphi.

Lima hamlini.

Araeosoma sp.

Solemya aff. S. johnsoni.

Limopsis phrear.

DEPTH FREQUENCY GRAPHS OF MODERN PACIFIC COAST MOLLUSKS AND ECHINOIDS ALLIED TO REPETTO FOSSILS. 

Width of graph at midpoint between depth division lines represents percentage of dredging records for that species within depth unit. Numbers in vertical columns represent number of dredging records; those in parentheses represent number of lots that lack depth records. Data based on collections of U. S. National Museum.
GHOUMIOAL SUUVKY PKOFESSIONAL PAPER 190 PLATE 4

C.San Fernando '\ GABRIEL/MOUNTA

Valley

!\Glerviale"""»,,,,.

*^?nr,,,,,A

7,8,10,11 -. *$Mffi°$l!s

 '~los Angeles ©

A SUALLOW-WATKK, J-AND, AND IVRESH-WATKH FOSSILS

1. Ostroa vosportlua. 8. Uoa hamlini.

2. Amulnra carnuloon.sis. 0. Callianassa sp.

3. l^yropocton wrrosensis. 10. Maucalla californiensis.

4. Trnchyvnrdlum cf. T. iiuadragentirluni. 11. Pluus cf. P. radiata.

C. Macrocalllsta sp. 12. Leaves of dicotyledonous

0. Oorbula plbblformls. land plants.

7. Astraca cf. A. Rradutu. 13. Astacus? sp.

Oil Field 

SHALLOW-WATER TO DEEP-WATER FOSSILS

1. Katherinella aft. KT. subdiaphana.

2. Limatula afl. L. "subauriculata."

3. Lunatia cf. L. caurina.

4. Acila? cf. A. castrensis.

5. Fusitritou afl. F. oregonensis.

 DEEP-WATER FOSSILS

1. Lima hamlini.

2. Hyalopecten aft". H. randolphi tlllamookensis.

3. Hyalopecten afl. H. randolphi.

4. Limopsis phrear.

5. Solemya aff. S. johnsoni.

6. Araeosoma sp.

7. Lucinoma afl. L. aequizonata.

MAP OF LOS ANGELES BASIN SHOWING DISTRIBUTION OF REPETTO FOSSILS OF DIFFERENT DEPTH FACIES. 

Base adapted from Hoots and Kew (16th Internet. Geol. Cong. Guidebook 15, pi. 6,1932)>
INFERRED ENVIRONMENT OF LARGER^FOSSILS 15

The genus Araeosoma is a representative of the 

family Echinothuriidae, which embraces echinoids that 

have a leathery flexible test. This family has a widespread distribution in deep water. One oriental genus 

(Asthenosoma), however, lives in shallow water from the 

littoral zone to a depth of about 50 fathoms, and 

Asthenosoma varium has been observed feeding on 

human feces along the shore.56 Araeosoma is represented in the eastern Pacific by A. eurypatum,51 from 

a depth of 671 fathoms near the Galapagos, and A. 

leptaleum,58 dredged off Panama at a depth of 581 

fathoms. The undeterminable species of Araeosoma 

from the Repetto formation is the first fossil echinothuriid recorded from America and apparently the first 

Tertiary representative of the family from any region 

in the form of more complete material than isolated 

spines.

Modern allies of Lima hamlini, Limopsis phrear, 

and Araeosoma sp. have not yet been found in the eastern Pacific north of the Panamanian region. Future 

dredging may show that the apparent extinction of 

these forms in the region along the coast of California 

is not real. If the apparent extinction is due to inadequate dredging records, modern representatives of 

these forms might be expected in depths greater than 

1,000 fathoms off the California coast, which appears 

improbable. The Albatross occupied about 100 deepwater dredging stations along the coast from Puget 

Sound to San Diego and almost the same number 

along the coast from Lower California to Panama. 

None of the hauls in the northern division were at 

depths greater than about 1,000 fathoms, whereas 

23 hauls in the southern division were taken at depths 

between 1,000 and 2,300 fathoms.59

The remaining species in the group of fossils of deepwater facies have modern analogs off the coast of 

California.

INTERPRETATION OF FOSSIIS OF DEEP-WATER FACIES

The meager Repetto fauna of larger fossils now known 

embraces species of shallow-water facies, species of 

deep-water facies, and others of intermediate-depth 

facies.

If only one or two species of deep-water facies were 

found in the Repetto formation, it might be argued that 

there is a reasonable doubt whether the fossils lived in 

the same environment as their modern analogs that 

is, whether the assumption on which this discussion is 

based is justified. But the graphs show seven species

w Mortensen, Th., A monograph of the Ecbinoidea, II, pp. 112, 279, Copenhagen, 

1935.

 'Agasslz, Alexander, and Clark, H. L., Hawaiian and other Pacific Echini: Harvard College Mus. Comp. Zoology Mem., vol. 34, pp. 181-183, pi. 66, figs. 18, 19; 

pis. 73-75,1909.

" Idem, pp. 183-186, pis. 76-77.

69 Data from Townseud, 0. H., Dredging and other records of the United States 

Fish Commission steamer Albatross: U. S. Fish Comm. Rept. for 1900, pp. 387-562, 

pis. 1-7,1901.

145509 38 2

of deep-water facies. The sponge is an additional 

species, and four others may be represented. The 

seven species of deep-water facies shown on the graphs 

belong to six genera. These genera, or the subgenera 

represented, are not known to embrace modern California species of shallow-water or intermediate-depth 

range, with the exception of Lucinoma. One modern 

species of Lucinoma, L. annulata, has an intermediatedepth range along the coast of California (10 to 414 

fathoms). This species appears to be well differentiated from the deep-water L. aequizonata. Moreover, 

three of the species of deep-water facies (Lima hamlini, 

Limopsis phrear, and Araeosoma sp.) belong to genera 

or subgenera that so far have not been found in the 

Pliocene deposits of any other region on the Pacific 

coast. The other four species represent genera that 

are not recorded in southern California Pliocene 

deposits characterized by a shallow-water facies, 

again with the exception of Lucinoma. Solemya is 

recorded from the Pliocene of the Eel River Basin, in 

northern California, where it is associated with species 

of cool-water facies. Hyalopecten is recorded from a 

locality in the Pliocene of the western part of the 

Ventura Basin. As it is the only species recorded 

from this locality, the facies is uncertain. Forms of 

Lucinoma annulata are found at many California 

localities in Pliocene strata of shallow-water facies.

The fossils of deep-water facies evidently are unusual. 

Those of shallow-water and intermediate facies are not 

unusual in California, with the exception of Limatula, 

one of the group of intermediate-depth facies.

The possibility that the fossils of deep-water facies 

represent cool shallow water instead of cool deep water 

needs consideration. That they represent shallow 

water cooled by changes in climate or oceanic circulation appears improbable. Some of the associated 

shallow-water fossils are of warm-water facies, and 

apparently none are of unequivocal cool-water facies. 

The lower Pliocene shallow-water faunas of southern 

California are generally thought to indicate a warmer 

facies than the modern fauna in the same latitude. 

Some conflicting evidence on this matter is apparent, 

but evidence for a pronounced lowering of the temperature of the lower Pliocene shallow seas is not.

The present California coast is marked by regions of 

pronounced upweUing of cool water. The upwelling is 

generally attributed to displacement of warmer surface 

water near the coast by offshore currents set in motion 

by winds blowing roughly parallel to the coast from a 

northerly quadrant.60 Inasmuch as the modern deep00 Bigelow, H. B., and Leslie, Maurine, Reconnaissance of the waters and plankton 

of Monterey Bay, July 1928: Harvard College Mus. Comp. Zoology Bull., vol. 70, 

pp. 464-478,1930. Literature citations may be found in this account. For a discussion of upwelling along the Pacific coast of South America, where this feature was 

recognized as a result of observations made during the voyage of the Venus a century 

ago, see Murphy, R. C., Oceanic .birds of South America, vol. 1, pp. 95-97, 267-268, 

New York, 1936.
16 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

water species shown on plate 3 have not been found in 

shallow water, even in regions of pronounced upwelling, 

it is improbable that upwelling was a major factor in 

introducing animals of deep-water facies into the Pliocene basin. It might be postulated that conditions 

were favorable for exceptionally pronounced and longcontinued upwelling in the Pliocene Los Angeles Basin, 

but that postulate implies exceptional localization that 

should be supported by independent evidence.

As it is unlikely that the fossils of deep-water facies 

lived in cool shallow water, the probability that they 

lived in deep water is considered reasonably certain.

DISTRIBUTION OF FOSSILS OF DIFFERENT DEPTH FACIES

The distribution of the three groups of fossils is shown 

on plate 4. Land and fresh-water fossils a flightless 

shore bird (Mancalla californiensis), cone scales of a pine; 

similar to a modern coastal species (Pinus cf. P. radiata), 

undeterminable dicotyledonous leaves, and a doubtfully : 

identified crayfish (Astacus?) -are shown by the same 

symbol as that used for fossils of shallow-water facies. 

The following fossils, whose depth facies is uncertain, 

are omitted from the map:

Repelto fossils omitted from distribution map (pi. 4) and their 

probable depth facies

Probable depth facies 

Stephanocyathus? sp ______________ Deep water.

"Nassa" hamlini Arnold_-___-_____ Intermediate or deep

water. 

Plicifusus? sp___________________ Deep water.

Buccinum? sp.------------------- Do.

Acila semirostrata (Grant and Gale) _ Intermediate.

Phreagena lasia Woodring, n. gen., Shallow water or intern. sp. mediate. 

Calyptogena n. sp________________ Do.

Periplorna cryphia Woodring, n. sp., Deep water.

and var. stenopa Woodring, n. var. 

Cassidulid.______________________ (?).

Fossils of shallow-water facies have so far been found 

at localities along -the northern margin of the basin and 

nearby, and in the Playa del Rey field, at the western 

margin of the basin. The fossils of intermediate-depth 

facies have a wider distribution in Los Angeles and in 

the Montebello, Whittier, Santa Fe Springs, Ingle wood, 

Dominguez, and Torrance fields. Fusitriton aff. F. 

oregonensis is the most widely distributed species of this 

group. The fossils of deep-water facies have an 

extensive distribution within the basin and on the 

northern and southern borders.

PALEOGEOGRAPHIC IMPLICATIONS

Paired pelecypods that do not have a closely inter-' 

locking hinge suggest burial close to the places where 

they lived. The following fossils of deep-water facies 

are represented by paired specimens: Solemya aff. S. 

johnsoni, from the Montebello field; Limposis phrear, 

from the Dominguez field; and Lima hamlini, from Los 

Angeles, the Rosecrans field, and a locality near the

Lawndale field. Limoposis has a closely interlocking 

hinge; Solemya and Lima have virtually no hinge.

The widespread distribution of fossils of deep-water 

facies indicates considerable depths over the greater 

part of the basin. According to Wissler's age assignments, the fossils of deep-water facies have a stratigraphic distribution at intervals throughout the greater 

part of the formation. The localization of the shallowwater fossils is probably to be attributed to proximity 

to areas of shallow water near the margins of the basin 

rather than to movements that changed the depth of 

the water over a large part of the basin. The occurrence 

of land and fresh-water fossils near the northern margin 

of the basin, in addition to the shallow-water, intermediate, and deep-water fossils, points to proximity to 

land. The mollusks of shallow-water facies from the 

Third Street tunnel in Los Angeles consist of broken 

and worn specimens, suggesting transportation by some 

unknown agency. A core that yielded two forms of 

shallow-water fossils constitutes the only record for the 

East Coyote field. One of these fossils (Corbula gibbiformis) is a paired pelecypod that does not have a 

closely interlocking hinge. Additional records are 

needed from the East Coyote field to support the suggestion that an area of shallow water lay in this part of the 

basin or nearby.61

Land-plant debris appears to be abundant in the 

northern part of the basin. The Albatross dredged 

great quantities of decomposed land-plant debris in deep 

water off the Pacific coast of Central America.62 

Perhaps the occurrence of the echinothuriid Araeosoma 

in the West. Coyote field is to be correlated with the 

abundance, of plant debris. Mortensen' 63 found that 

echinothuriids dredged in deep water off the Philippine 

and Kei Islands have their intestines more or less filled 

with finely divided land-plant debris, and he commented 

on the paradox of deep-sea animals feeding on land 

plants.

The source of the big, thick-shelled, shallow-water 

Anadara from the Playa del Rey field is not known. It 

shows signs of transportation, for part of the shell well 

within the core is broken and worn. It might be argued 

that the schist ridge that underlies the Playa del Rey 

field 64 formed an area of shallow water during at least 

part of Repetto time. However, the occurrence of the 

deep-water Lima in another well in this field at about 

the same horizon as the Anadara is opposed to this 

view. ShaUow-water or land, part of Reed's Catalinia,65

si Collections from two additional wells in the East Coyote field submitted by 

Wissler too late to be included in this report do not include any forms of deep-water 

facies. ;

62 Agassiz, Alexander, General sketch of the expedition of the Albatross from February to May, 1891: Harvard College Mus. Comp. Zoology Bull., vol. 23, pp. 11-12,1892.

1 am indebted to Dr. T. Wayland Vaughan for pointing out this description.. 

63 Mortensen, Th., A monograph of the Echinoidea, II, pp. 112-113, 2^5,. Copenhagen, 1935. .. ' '."' ..

64 Hoots, H. W., Blount, A. L., and Jones, P. H., Marine oil shale, source of oil-in 

Playa delRey field, California: Am. Assoc. Petroleum Geologists Bull., vol... 19,. fig.

2 (opp. p. 177), 1935. ( ..' ' ' "''

65 Reed, R. D., Geology of California, fig. 51 (opp. p. 253), Tulsa', 1933:' (See also 

fig. 20, opp. p. 117.)
INFERRED ENVIRONMENT OF LARGER FOSSILS 17

may. have lain not far south of the northern border of 

the Palos Verdes Bills. Though the Repetto along the 

northern border of the Palos Verdes Hills contains the 

deep-water Lima, it also contains scattered small 

pebbles of schist and. basaltic rock.

A fossil of intermediate-depth facies (Katherinella aff. 

K. subdiaphana) is known from the Torrance field, and 

one (Acila semirostrata) probably of the same facies from 

the Wilmtngton field. Both records are the only ones 

for these areas.

The fossils of deep-water facies suggest that during 

Repetto time the Los Angeles Basin sea had depths of 

300 to 600 fathoms (roughly 2,000 to 4,000 feet). Part 

of the basin doubtless contained deep water before the 

beginning of the Pliocene epoch. Kleinpell estimated 

that the Foraminifera of the Malaga mudstone member 

of the Monterey shale, underlying the Repetto in the 

Palos Verdes Hills, indicate a depth of 500 fathoms or 

more. 00 Evidence that the upper part of the subsurface 

Miocene in the basin carries larger fossils of deepwater facies is afforded by material in the Standard 

collection from horizons assigned by Driver and Wissler 

to the Miocene. In addition to the specimens of 

Hyalopecten aff. H. randolphi, H. cf. H. pedroanus, 

Lima hamlini, and Lucinoma aff. L. aequizpnata cited 

under the description of species, this material includes 

part of a large Propeamussium (Bradford Oil Co. B. & 

B. No. 1, southest of Hiintington Beach field, depth 

3,810 feet, U. S. G. S. locality 13910) unlike any known 

modern species in the eastern Pacific, but allied to 

deep-water species in other parts of the world.

At outcrop localities in Los Angeles and at Potrero 

Canyon localities considered under the heading "Age 

relations of larger fossils" the Pico formation, which 

overlies the Repetto formation and is assigned to the 

upper Pliocene, contains larger fossils of intermediatedepth facies. According to age assignments by Driver 

and Wissler, the lower part of the Pico in the subsurface 

section contains the following larger fossils of deep-water 

facies: Hyalopeden aff. H. randolphi, H. aff. H. randotphi 

tillamookensis (records cited under descriptions of species), and Nuculana aff. N. leonina (Dall) (Standard 

Oil Co. Vickers No. 1 lease, No. 28, Inglewood field, 

depth 1,256 feet, U. S. G. S. locality 13889; Southern 

California Drilling Co. Matteson No. 1, El Segundo 

field, depth 2,599 feet, U. S. G. S. locality 13912a). A 

species, apparently of shallow-water facies, Sinum? cf. 

S. californicum Oldroyd (Pan American Petroleum Co. 

Pacific Southwest No. 2, El Segundo field, depth 1,149 

feet, U. S. G. S. locality 13913), and one of uncertaindepth facies, Phreagena lasia (cited under descriptions 

of species) also are assigned to the Pico formation.

to Kloiupoll, R. M., in Woodrlng, AV. P., Bramlette, M. N., and Kleinpell, R. M., 

Miocene stratigraphy and paleontology of Palos Verdes Hills, California: Am. Assoc. 

Petroleum Geologists Bull., vol. 20, p. 148,1036.

In general terms the Repetto formation has a deepwater facies over a large part of the basin; the Pico 

formation has a moderately deep-water and intermediate-depth facies; and the Pleistocene has a shallowwater facies. This succession suggests that the deposition of sediments of decreasing-depth facies during 

Pliocene and Pleistocene time was a factor in the accumulation of the 6,000 to 10,000 feet of Pliocene and 

Pleistocene sediments in the Los Angeles Basin. But 

unless the Repetto sea was much deeper than now appears probable, subsidence also was a factor in the 

accumulation of these sediments.

Stratigraphic data for the larger fossils may yield 

information to test the implication that, possible subsidence disregarded, the Repetto formation itself represents decreasing depth facies. Two collections of fossils 

at horizons assigned by micropaleontologists to the 

transition zone between the Repetto°and Pico formations in the Repetto Hills are listed under the heading 

"Age relations of larger fossils." One of the collections 

consists of species of shallow-water facies and others of 

uncertain-depth facies. Most of the specimens in this 

collection are incomplete, but their condition is due 

principally to difficulties in extracting them from the 

hard limy matrix; and none of the pelecypods are paired. 

The other collection includes one species (Yoldia aff. 

T. thraciaeformis) that, if correctly identified, is of coolwater, possibly deep-water facies. A form similar to 

the Arctic and Aleutian Y. thraciaeformis is represented 

in the collections of the National Museum by specimens 

dredged at depths of 152 to 1,006 fathoms along the 

California coast. Another species (Acila semirostrata) 

is classified in the group of intermediate-depth facies, 

and others are of shallow-water or uncertain facies. In 

preservation and matrix this collection is similar to the 

one just mentioned. One specimen of Acila, which has 

a closely interlocking hinge, is a paired mold. These 

two collections may represent accidental-death associations, but they indicate a shallower facies than the 

Third Street tunnel locality in Los Angeles and most of 

the subsurface localities.

This interpretation of the history of the Los Angeles 

Basin is not new. It is implied in Natland's analysis of 

the succession of foraminiferal faunas in the Ventura 

Basin, where the succession is essentially the same as in 

the Los Angeles Basin. Reed, who used Natland's 

data and suggested that the water generally was too 

deep for bottom-dwelling mollusks, presented this interpretation. 67 Natland 68 found that the succession of 

associations of Foraminifera with increasing depth in a 

profile across the channel between San Pedro Bay and 

Santa Catalina Island closely resembles the downward 

succession of foraminiferal faunas in the Pleistocene and

67 Reed, R. D., Oil-bearing Pliocene beds of southern California [abstract]: PanAm. Geologist, vol. 59, p. 231, 1933.

88 Natland, M. L., The temperature and depth distribution of some Recent and 

fossil Foraminifera in the southern California region: California Univ., Scripps Inst. 

Oceanography, Bull., Tech. ser., vol. 3, pp. 225-230,1 table, 1933.
18 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Pliocene of the Ventura Basin. The possibility that 

the different temperature facies of the fossil faunas is 

due to change in climate or other changes not correlated 

with depth is not excluded in Natland's discussion.69

COMPARISON BETWEEN LOS ANGELES BASIN DURING 

REPETTO TIME AND MODERN DEEP-WATER BASINS ON 

CONTINENTAL SHELF OF SOUTHERN CALIFORNIA

The conception of the Los Angeles Basin as a deepwater basin during Repetto time invites comparison of 

the Los Angeles Basin with tbe basins on the Continental Shelf of southern California shown in figure 1. 

Despite their location on the Continental Shelf, these 

basins have depths of 300, 500, 700,.and 1,000 fathoms. 

They may fairly be claimed to have had a tectonic 

origin, as they are exceptional features in a region of 

marked crustal instability. Apparently some of the 

deformation took place recently, for Pleistocene elephants are found on Santa Cruz, Santa Rosa, and San 

Miguel Islands.70

The morphologic similarity between the basins on 

the Continental Shelf of southern California and the 

Pliocene Los Angeles and Ventura Basins on the adjoining mainland has been pointed out by Trask 7i and 

Reed.72 Trask 73 found that sand is being deposited 

on ridges between the basins regardless of depth and 

that the organic content of the fine-grained sediments 

in the basins is exceptionally high for modern sediments. Many California geologists have been loath 

to think, however, that the depth of the water in the 

Pliocene basins was nearly as great as in the modern 

basins. According to the interpretation of the depth 

facies of the larger Repetto fossils from the Los Angeles 

Basin here offered, there is a reasonable probability 

that the depth was as great as in some of the basins on 

the Continental Shelf.

Geologists would be under a great debt to oceanographers for a detailed survey of the physical and 

biologic features of this part of the Continental Shelf 

of southern California. The Pliocene and modern 

basins appear to be similar in general features. A 

detailed survey might yield results of great value in 

interpreting the geologic history and the conditions 

during the accumulation of the sediments that are 

regarded as the source beds of petroleum in the Los 

Angeles and Ventura Basins.

It may be worth while for sedimentary petrologists 

to study the Repetto sediments with the probable deepwater origin of the formation in mind. These studies

69 Natland, M. L., op. cit., p. 230.

 ~o The data for the three islands are summarized in the most recent account: Stock, 

Chester, Exiled elephants on the Channel Islands, California: Sci. Monthly, vol. 41, 

pp. 205-214, 10 figs., 1935.

71 Trask, P. D., Origin and environment of source sediments of petroleum, p. 119, 

Houston, 1932.

71 Eeed, R. D., Geology of California, pp. 3-5, Tulsa, 1933; Oil-bearing Pliocene 

beds of southern California [abstract]: Pan-Am. Geologist, vol. 59, p. 231,1933.

78 Trask, P. D., Sedimentation in the Channel Islands region, California: Econ. 

Geology, vol. 26, pp, 24-43, 6 figs., 1931; op. cit. (1932), pp. 88-90, 119-124, 237-238.

combined with comparison with the sediments in the 

modern California deep-water basins may yield criteria 

for the recognition of deep-water sediments that superficially resemble shallow-water sediments. Such criteria would be particularly useful in attempts to evaluate the depth facies of older sediments, for with greater 

age the decreasing similarity to modern faunas renders 

paleontologic data of doubtful value. If, on the other 

hand, it is found that the Repetto sediments are not 

comparable with those being deposited in the modern 

deep-water basins, some explanation for the fossils of 

deep-water facies other than a deep-water habitat may 

be preferred.

AGE RELATIONS OF LARGER FOSSILS

The Repetto formation is currently assigned to the 

lower Pliocene, as it overlies strata considered of upper 

Miocene age and constitutes the lower part of the 

section referred to the Pliocene. The designation lower 

Pliocene is a relative one for this region. The age 

relations with reference to the European Miocene and 

Pliocene are not directly known. Direct comparison 

with the time scale adopted for the continental Tertiary 

of the Pacific coast and Great Basin also is impracticable, with the following exception. A tooth referred 

to Hipparion mohavense has been found in an area of 

diatomaceous shale assigned to the upper part of the 

Puente formation in the San Jose Hills, north of the 

Los Angeles Basin.74 The Puente formation is considered of upper Miocene age. This species of Hipparion was described from the Ricardo formation of 

the Mojave Desert, north of the San Gabriel Range. 

The Ricardo formation is generally assigned to the 

lower Pliocene but by some workers is considered late 

Miocene or transitional Miocene-Pliocene. English 75 

realized that units mapped as the upper part of the 

Puente might at places be of Pliocene age, and since 

then Repetto Foraminifera have been found in an area 

mapped as Puente.76 According to a communication 

from Wissler, however, the diatomaceous shale in the 

area where the tooth was collected is of Miocene age 

in terms of the time scale used for the marine section.

FOSSILS OF DEEP-WATER FACIES

Some of the fossils of deep-water facies in the Repetto 

formation of the Los Angeles Basin represent genera 

or subgenera that so far have not been found elsewhere 

in the California Pliocene. These unusual fossils give 

the Repetto fauna a distinctive character, which so far 

as known has a chronologic value in the Los Angeles 

Basin. But inasmuch as the deep-water forms are

74 Stock, Chester, A tooth of Hipparion mohavense from the Puente formation, 

California: Carnegie Inst. Washington Pub. 393, pp. 49-53,1 fig., 1928.

« English, W. A., Geology and oil resources of the Puente Hills region, southern 

California: U. S. Geol. Survey Bull. 768, pp. 36-38, 1926.

76 Stewart, R. E., and Stewart, K. C., "Lower Pliocene" in eastern end of Puente 

Hills, San Bernardino County, California: Am. Assoc. Petroleum Geologists Bull., 

vol. 14, pp. 1445-1450, 1 fig., 1930.
AGE RELATIONS OF LARGER FOSSILS 19

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20 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

facies fossils, and inasmuch as most of them are closely 

allied to modern species and many are allied to older 

forms, a similar fauna might be expected at other 

horizons. Indeed, some of the species of deep-water 

facies are now known in the Los Angeles Basin at 

horizons assigned to the underlying Miocene and to 

the overlying Pico formation.

Though most of the fossils of deep-water facies 

closely resemble species living in the eastern Pacific, 

related forms have not been found in the California 

Pleistocene, presumably owing to the absence of a 

similar facies. That a similar facies is represented in 

formations older than the Repetto is indicated by the 

occurrence of similar forms. In fact, Limopsis phrear, 

Araeosoma sp., and the sponge are the only species of 

deep-water facies still unrepresented by similar forms 

in older formations. Hyalopecten is abundant in the 

Miocene Monterey shale and in the Eocene and 

Oligocene Kreyenhagen shale. The Miocene Astoria 

formation of Oregon contains Stephanocyathus?, Solemya, 

Hyalopecten, and a form of the Lucinoma aequizonata 

group. Weaver's Blakeley formation of Washington, 

which is generally considered of Oligocene age, contains 

Solemya, Hyalopecten, and possibly a Periploma similar 

to P. cryphia. A giant Lima is represented in strata 

assigned to the Oligocene on the south shore of the 

Strait of Juan de Fuca, Washington, and also in the 

Oregon Oligocene. Tegland estimated that the finegrained sediments of the Blakeley formation were 

deposited at depths of at least 1,000 fathoms.77

FOSSILS OF INTERMEDIATE AND SHALLOW-WATER FACIES

The number of species of intermediate and shallowwater facies is too small to justify an attempt to make 

a detailed analysis of their age relations. Also the 

faunal relations of the Pliocene formations in different 

parts of southern California are uncertain, owing to 

the lack of stratigraphically controlled successions of 

faunas in many areas and to the possibility that facies 

differentiation is more significant than age differentiation.

Comparison with other Pliocene faunas from Los 

Angeles Basin. Other Pliocene faunas from the Los 

Angeles Basin are briefly considered for comparison 

with the Repetto fauna.

The following fossils, represented by poorly preserved 

material, were collected in the type region of the 

Repetto formation in the Repetto Hills at localities 

pointed out by Alex Clark. Though these localities 

appear to fall in the Repetto formation as originally 

defined, they are, according to Clark, assigned by 

micropaleontologists to the transition zone between 

the Repetto and Pico formations.

77 Tegland, N. M., The fauna of the type Blakeley upper Oligocene of Washington: 

California Univ., Dept. Oeol. 8ci., Bull., vol. 23, p. 102,193?.

Fossils from transition zone between Repetto and Pico formations 

in Repetto Hills

TJ. S. G. S. locality 13614. Repetto Hills, road cut near top 

of slope west of Atlantic Boulevard, 0.33 mile S. 32° E. from 

735-foot triangulation station between Atlantic Boulevard and 

Garvey Avenue. Limy concretion in siltstone. W. P. Woodring 

and Alex Clark, August 1935: 

Gastropods:

Astraea cf. A. gradata Grant and Gale.

Neverita aff. N. reclusiana (Deshayes).

Calyptraea aff. C. mamillaris Broderip.

Calyptraea aff. C. radians (Lamarck).

Crepidula cf. C. onyx Sowerby.

Turritella cf. T. goniostoma Valenciennes.

Aletes? cf. A. &quamigerus Carpenter.

"Nassa" hamlini Arnold.

"Nassa" cf. "N." californiana (Conrad).

"Nassa" sp.

"Neptunea"? cf. "N." humerosa Gabb.

"Cancellaria" hemphilli Dall. 

Pelecypods:

Yoldia cf. Y. cooped Gabb.

Anadara aff. A. trilineata (Conrad).

Volsella? sp.

Pecten sp.

Ostrea sp.

Trachycardium cf. T. quadragenarium (Conrad).

"Protocardia" cf. "P." centifilosa (Carpenter).

Macrocallista? sp.

Callithaca aff. C. tenerrima (Carpenter).

Katherinella aff. K. subdiaphana (Carpenter).

Chione cf. C. fernandoensis English.

Macoma? sp.

Solen cf. S. sicarius Gould.

Panomya? sp.

U. S. G. S. locality 13616. Repetto Hills, west branch of 

ravine between Atlantic Boulevard and Garvey Avenue, 0.32 

mile S. 30° W. from 735-foot triangulation station. Hard limy 

layer in sandstone. W. P. Woodring and Alex Clark, August 

1935:

Gastropods:

Neverita? sp.

Calyptraea aff. C. mamillaris Broderip.

Turritella cf. T. cooperi Carpenter.

"Neptunea"? cf. "N." humerosa Gabb. 

Pelecypods:

Acila semirostrata (Grant and Gale).

Yoldia aff. Y. thraciaeformis (Storer).

Anadara? sp.

Patinopecten? sp.

Lucinoma sp.

"Nassa" hamlini, Acila semirostrata, and forms similar to Astraea cf. A. gradata and Katherinella aff. K. 

subdiaphana occur in the Repetto formation. "Neptunea"'! cf. "N." humerosa and Chione cf. C. Jernandoensis suggest forms found at the base of the Pliocene 

section in Elsmere Canyon, at the east end of the 

Ventura Basin, where Pliocene strata overlap the 

granitic rocks of the San Gabriel Range. The Elsmere 

Canyon fauna is generally considered of lower Pliocene 

age. "Cancellaria" hemphilli occurs at San Diego 

in the San Diego formation, which is currently considered middle Pliocene,
AGE RELATIONS OF LARGER FOSSILS 21

The relative stratigraphic position of the Pliocene 

larger fossils from the Puente Hills with reference to the 

Repetto and Pico formations is unknown or has not 

been recorded. English 7S found fossils in a zone 

about 3,000 feet above the base of the 5,000-foot 

section assigned to the Pliocene. Eldridge's collections 

from localities 3907 (Olinda Hill, south of western 

wells of Fullerton. Consolidated Oil Co.) and 3909 

(face of ridge north of Brea Canyon opposite wells of 

Brea Canyon Oil Co.) are the only ones in the National 

Museum. Two of Eldridge's collections appear to be 

lost (3908, 3910). Many of the species listed by 

Arnold 70 from the Puente Hills are not in the two 

collections extant. Lyropecten cerrosensis (locality 

3907) and. Ostrea vespertina (locality 3909 80) occur in 

the Repetto formation. A form of Fusitriton oregonensis (locality 3907) and Anadara aff. A. multicostata (locality 3909) appear to be more closely 

similar to modern forms than to forms from the 

Repetto formation. Lyropecten cerrosensis and Chlamys 

afF. C. etchegoini (locality 3907) have been considered 

characteristic species of the San Diego formation. 

Other fossils from the Puente Hills were described or 

recorded by Carson,81 including Cantharus breaensis 

and Solenosteira angelensis, which are considered forms 

of "Neptunea" humerosa, and Chione elsmerensis and 

Chione Jernandoensis. All these species occur in the 

Elsmere Canyon fauna of the Ventura Basin.

A small Pliocene fauna characterized by the abundance of Pectinidae and brachiopods is found in sandstone at Temescal Canyon, near Santa Monica (third 

canyon, northwest of Santa Monica on pi. 2).82 Virtually every species in. this fauna is recorded from the 

San Diego formation at Pacific Beach, near Sa,n Diego. 

The same Pliocene fauna is recorded from the south 

slope of the Santa Susana Mountains, between the 

'Ventura Basin and the Los Angeles Basin. 83 The sandstone carrying these fossils, referred to the Saugus formation, by Kew, appears to represent an extension of 

the sea from the Ventura Basin. At the time when it 

was laid, down the sea may have extended, from the 

Ventura Basin to the Los Angeles Basin across San

" English, W. A., Geology and oil resources of the Puonlo Hills region, southern 

California: U. S. Gool. Survey Bull. 708, p. 42,1926.

» Arnold, Ralph, in Eldridgo, G. H., and Arnold, Ralph, The Santa Clara Valley, 

Puento Hills, and Los Angolos oil districts, southern California: U. S. Geol. Survey 

Bull. 309, p. 107, 1907.

«° The locality number 3809 on tho specimens of this species appears to be an error 

for 3909.

81 Carson, C. M., Some now species from the Pliocene of southern California: Southern California Acad. Sci. Bull., vol. 24, pp. 31-35, p. .1, 1925. Carson, C. M., Now 

molluscan species from tho Californian Pliocene: Idem, vol. 25, pp. 49-62, pis. 1-4, 

1926.

11 Arnold, Ralph, Now and characteristic species of fossil mollusks from the oilbearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 32, 

p. 527, 1907. . Arnold, Ralph, in Eldridge, G. H., and Arnold, Ralph, op. cit. (Bull. 

309), p. 163. Woodring, W. P., In Hoots, H. W., Geology of the eastern part of the 

Santa Monica Mountains, Los Angeles County, Calif.: U. S. Geol. Survey Prof. 

Paper 165, p. 110,1031.

M Kew, W. 8. W., Oeology and oil resources of a part of Los Angeles and Ventura 

Counties, Calif.: U. 8. Oeol. Survey Bull. 763, pp. 84-85,88 (localities 8139,8144,8145, 

8161, 8153, 8164, 8167, 8160), 1024. Woodring, W. P., Pliocene deposits north ol Simi 

Valley, Calif.: California Acad. Sol. Proo., 4th ser., vol. 19, pp. 67-64,1030.

Fernando Valley. At the localities where this fauna 

is found it occurs in sandstone that overlaps rocks 

ranging in age at different places from Miocene to 

Cretaceous. Essential faunal identity would ordinarily 

be considered as indicating essential synchroneity for 

the Pliocene transgression at these localities, as I formerly assumed.84 The chronologic value of the fauna is 

not yet established, however, by its position in. stratigraphically controlled successions of faunas.

A large fauna from the upper part of the Pico formation in Los Angeles has been listed and discussed by 

Moody 85 and Grant. 86 The Recent species Trachycardium guadragenarium and Katherinella subdiaphana are 

the only species in this fauna that suggest Repetto 

forms. This fauna appears to represent water of 

moderate depth. At all events, the shallow-water genera 

Anadara, Ostrea, and Dendraster are absent. Essentially 

the same fauna occurs in the Pico formation in Potrero 

Canyon87 (the second canyon northwest of Santa Monica 

shown on pi. 2). Lyropecten cerrosensis, which occurs in 

the Repetto formation, is recorded from this locality. 

Though Potrero Canyon is only half a mile east of the 

adjoining Temescal Canyon, where the sandstone containing Pliocene fossils just mentioned is exposed, the 

field relation between the two Pliocene sections is undeterminable owing to the cover of the Santa Monica 

Plain. My attempt to fit this fauna into a chronologic 

climatic scheme 88 should be disregarded, as it was based 

on an assumption unsupported by independent evidence, 

and some of the faunal evidence is opposed to it.

Comparison with Pliocene faunas from Ventura Basin 

and San Diego region. The Pliocene mollusks of the 

Ventura Basin and San Diego region have recently been 

described or recorded by Grant and Gale,89 and the 

stratigraphy and faunal zones have been described by 

Gale. 90 The following Repetto fossils from the Los 

Angeles Basin are found in strata in the eastern part 

of the Ventura Basin assigned by Gale to the middle 

Pliocene: Acila semirostrata, Anadara camuloensis, 

Lyropecten cerrosensis, Ostrea vespertina, and Corbula 

gibbiformis. Astraea cf. A. gradata, from the Repetto 

formation, resembles A. gradata from strata in the eastern part of the Ventura Basin assigned to the middle 

Pliocene. Lyropecten cerrosensis and Ostrea vespertina 

occur in the San Diego formation, which was considered 

of middle Pliocene age by Gale.

In terms of Gale's age assignments, the few shallowwater fossils from the Repetto formation have a middle

84 Woodring, W. P., op. cit. (1930), pp. 61-63. Woodring, W. P., in Hoots, H. W., 

op. cit. (1931), p. 119.

85 Moody, C. L., Fauna of the Fernando of Los Angeles: California Univ., Dept. 

Geology, Bull., vol. 10, pp. 39-62, pis. 1-2,1916.

86 Grant, U. S., in Soper, E. K., and Grant, U. S., Geology and paleontology of a 

portion of Los Angeles, Calif.: Geol. Soc. America Bull., vol. 43, pp. 1058-1067, 1932 

[1933].

« Woodring, W. P., in Hoots, H. W., op. cit. (1931), p. 116.

8s Idem, p. 117.

«» Grant, U. S., IV, and Gale, H. R., Catalogue of the marine Pliocene and Pleistocene Mollusca of California: San Diego Soc. Nat. History Mem., vol. 1,1031.

*> Idem, pp. 26-39,46-40. Faunal lists for the localities discussed may be assembled 

from the records in the systematic part of the memoir.
22 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Pliocene aspect. If it is found that the shallow-water 

fossils represent horizons in the upper part of the 

Repetto formation, their assignment to the middle 

Pliocene is not in conflict with their occurrence in the 

Repetto formation, though a twofold subdivision of 

the Los Angeles Basin Pliocene appears preferable to 

a threefold subdivision. Larger fossils appear to be 

rare in the thick Pliocene section in the western part of 

the Ventura Basin. The stratigraphic position of 

Gale's middle Pliocene zone of the eastern part of the 

basin is not known in the western part of the basin, 

where the Repetto formation is recognized on the basis 

of its foraminiferal fauna.

DESCRIPTIONS OF SPECIES

MOLLUSKS

Family TURBINIDAE

Genus ASTEAEA ("Bolten") Roding

Subgenus POMAULAX M. E. Gray

Astraea (Pomaulax) cf. A. gradata Grant and Gale

Plate 5, figure 17

A large, poorly preserved and deformed Astraea in 

the Third Street tunnel collection was not mentioned 

by Arnold. It has a double undulated but not noded 

basal keel; and a wide band on the middle of the whorl 

has coarse nodes. Length (incomplete) 65.5 millimeters, greatest width (exaggerated by compression) 

90.5 millimeters. The sculpture suggets A. gradata 

Grant and Gale,91 expecially the form shown in their 

figures 3a, b. A. gradata was described from beds on 

both the north and south sides of Santa Clara Valley 

assigned to the middle Pliocene. This species was 

compared with the Recent A. turbanica (Dall), from 

Magdalena Bay, Lower California. The operculum 

in the aperture of the type and only specimen of A. 

turbanica in the collections of the National Museum 

has three narrow ribs, as compared with the broad ribs 

of opercula associated with shells of A. gradata, which 

more closely resemble opercula of the Recent Californian A. undosa (Wood). An incomplete operculum 

in the Elsmere Canyon collection (locality 4401) 

resembles, so far as it goes, the operculum associated 

with A. gradata figured by Grant and Gale. A. 

breaensis Carson,92 from the Pliocene of the Puente 

Hills, is strongly sculptured and may be allied to 

A. turbanica, but the type and apparently only specimen 

has nodes elongated in a protractive pattern.

« Grant, U. B., IV, and Gale, H. R., Catalogue of the marine Pliocene and Pleistocen.e Mollusca ol California: San Diego Soc. Nat. History Mem., vol. 1, pp. 818-819, 

pi. 31, figs, la, 6, 3a, b, 5, 8, 9,1931.

M Carson, C. M., New molluscan species from the Californian Pliocene: Southern 

California Acad. Sci. Bull., vol. 25, pp. 57,59, pi. 4, figs. 3,4,1926,

A. gradata and apparently also the Third Street tunnel 

form seem to be referable to Pomaulax M. E. Gray,93 

which is assigned subgeneric rank under Astraea**

Family NATICIDAE

Genus LUNATIA Gray

Lunatia cf. L. caurina (Gould)

Plate 5, figure 19

A small high-spired naticid from Standard Oil Co. 

Baldwin-Cienega No. 105, Inglewood field, depth 2,221 

feet (U. S. G. S. locality 13890), has a length of 8.4 

millimeters and a width of 6.8 millimeters. The outer 

lip and basal margin are broken back. The umbilicus 

is almost completely rilled with callus, but a narrow 

space is not covered. Very faint microscopic spiral 

markings are visible on the shell. This little shell 

resembles small Recent shells arranged under L. 

caurina (Gould).95 Specimens from the type region of 

L. caurina are larger and stouter than the fossil, and 

the umbilicus is a little more open; on some the callus 

has a slight depression. Lots arranged under this 

species represent a range from Alaska to San Diego, 

and along the coast from Washington to California 

they represent a depth range of 20 to 822. fa thorns. The 

umbilicus of Euspira acosmita Dall,96 dredged at depths 

of 34 to 822 fathoms off the coast of southern California, 

is completely filled with callus in a manner strikingly 

suggestive of Cryptonatica. E. acosmita seems to have 

been described from a single specimen, and Dall thought 

that when the operculum was known it might turn out 

to be a Cryptonatica. The type may be a Cryptonatica, 

but this seems improbable, as smaller shells in several 

lots have the same kind of callus pad, and some shells 

in these lots have a horny operculum. On unworn 

shells the callus fills the umbilicus regardless of shell 

size; and inasmuch as the callus edge shows no signs' 

of wear on the fossil from the Los Angeles Basin, it 

probably is not allied to this Recent form. The Recent 

shells include both low-spired and high-spired forms, 

the latter resembling the fossil in outline.

M Gray, M. E., Figures of molluscous animals, vol. 4, p. 87,1850. Subsequently 

designated type (Cossmann, Essais de palfioconchologie compared, pt. 11, p. 149,1918), 

Trochus japonicus Dunker, Recent, Japan. I have not seen any specimens of this 

species nor any description of the operculum. A more exhaustive search may reveal 

an earlier type designation of the Californian Trochus undosus Wood, which was 

Mrs. Gray's first species under Pomaulax. Stoliczka's claim that Trochus undosus 

Wood is the only species of Pomaulax (Cretaceous fauna of southern India, vol. 2, 

p. 357.1868) is not considered a type designation.

« Roding, P. F., in Bolten, J. F., Museum Boltenianum, pt. 2, p. 79,1798. Subsequently designated type (Suter, Manual of New Zealand Mollusca, p. 166,1913), 

Trochus imperialis Gmelin, Recent, New Zealand.

M Gould, A. A., [Descriptions of shells from collection of Exploring Expedition]: 

Boston Soc. Nat. History Proc., vol. 2, p. 239, 1847 (as Natica, Straits of De Fuca); 

Mollusca and shells: U. S. Expl. Exped., vol. 12, pp. 212-213, figs. 254, 254a, 1852 

(as Natica).

96 Dall, W. H., Descriptions of new species of Mollusca from the north Pacific 

Ocean in the collection of the Vnited States National Museum: U. S. Nat. Mus. 

Prop., YQ!', 56, p. 352,1919,
MOLLUSKS 23

The fossil is assigned to 'the genus Lunatia Gray,97 

the type of which has an open umbilicus. The type of 

Natica ampullaria, the type species of Lunatia, was 

figured by Delessert.98 Deshayes," following Reclus,

 considered N. ampullaria a high-spired form of N. 

monilifera. The Arctic and temperate Naticidae characterized by a horny operculum appear to be generically 

removed from the tropical Polinices Montfort; 1 it is 

improbable that they are allied to the Eocene Euspira 

Agassiz.2

An undetermined naticid Arnold's "Neverita recluziana Petit" 8 is represented by an imperfect poorly 

preserved specimen in the Third Street tunnel collection. Another undetermined naticid, possibly Lunatia, 

was obtained from a core in Union Oil Co. Hellman

 No. 10, Dominguez field, at a depth of 4,193 feet.

Family CYMATIIDAE

'Genus FUSITRITON Cossmann

Fusitriton aff. F. oregonensis (Redfield)

Plate 5, figures 21-23

Priene oregonensis Redfield var. angelensis Arnold, U. S. Nat. 

Mus. Proc., vol. 32, pp. 527 (list), 536-537, pi. 50, fig. 11, 

1907. Third Street tunnel, Los Angeles; probably equivalent of middle Fernando formation, lower Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43,

 ' p. 1058 (Arnold's list), 1932 (1933). Third Street tunnel, 

Los Angeles; middle Pliocene.

Priene oregonensis Redfield var.? angelensis Arnold. Arnold, in 

Eldridge and Arnold, U. S. Geol. Survey Bull. 309, pp. 152 

(list), 252, pi. 40, fig. 11, 1907. Third Street tunnel, Los 

Angeles; Fernando formation, lower Pliocene.

Ranella (Priene) oregonensis (Redfield) variety angelensis 

(Arnold) Grant and Gale, San Diego Soc. Nat. History 

Mem., vol. 1, pp. 40 (discussion), 738, 1931.

tArgobuccinum n. sp. (an uncited worker in) Reed, Geology of 

California, p. 230, 1933. Repetto formation; Pliocene.

A Fusitriton closely resembling F. oregonensis. 

Varices weak or absent. Bibs generally subdued and 

generally relatively closely spaced on later whorls of 

large shells.

Length (incomplete) 73 millimeters, width (crushed) 

42 millimeters (holotype of angelensis}. Length of body

m Gray, J. E., A list of the genera of Recent Mollusca, their synonyma and types: 

Zool. Soo. London Proo., 1847, p. 149. Originally designated type, Nlatica] ampullaria Lamarck (considered a form of Nalica monilifera Lamarck), Recent, Europe.

«s Dolessert, B., Rocueil de coquilles dficrltes par Lamarck, pi. 32, figs, lla, 6.1841.

" Desbayes, O. D., Lamarck's Histoire naturelle des animaux sans vertebres, 

2d od., vol. 8, p. 026,1838. See also Bucquoy, E., Dautzenberg, Ph., and Dollfus, O., 

Los mollusquos marins du Roussillon, vol. 1, pp. 146-148, 1883.

1 Montfort, Denys. de, Oonchyliologle syst6matique, vol. 2, pp. 222-223, 1810. 

Originally designated type, Polinices albus Montfort (=Natica mammiltaris Lamarck 

^Natica brunnea Link), Recent, West Indies.

8 Agassiz, L., in James Sowerby's Minoral-Conchologie Orossbrittaniens, pp. 14, 

15, 17, 1839. [For date see Shorborn, Index animalium, 1801-50, p. cxviii, 1922.] 

Subsequently designated type (Call, U. S. Qeol. Survey Prof. Paper 59, p. 87,1909), 

Natica glaucinoides Sowerby, Eocene, England. [Ball designated Natica labellata 

Lamarck as the type, but in the preceding synonymy he stated that Natica glaucinoides^ Natica labellata.]

' Arnold, Ralph, New and characteristic species of fossil mollusks from the oilbearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 32, 

p. 627 (list), 1907. Arnold, Ralph, in Eldridge, O. H., and Arnold, Ralph, The Santa 

Olara Valley, Puente Hills, and Los Angeles oil districts, southern California: U. 8. 

Oeol. Survey Bull. 809, p. 162 Olst), 1907. (The figured specimen is from .Elsmere 

Oanyon.)

whorl about 75.8 millimeters, width (crushed) 65.5 

millimeters (fragment of large specimen from Third 

Street tunnel). Length (incomplete) about 70 millimeters, width (crushed) 37.5 millimeters (largest core 

specimen, pi. 5, fig. 21).

This Fusitriton is the most abundant gastropod in the 

collection of core fossils and is represented by 11 specimens in the collection from the Third Street tunnel. 

The thin shells are broken and deformed, and the characters are not entirely clear. Arnold's claim that the 

canal is longer and less recurved than in the modern F. 

oregonensis (Redfield) 4 cannot be confirmed. On most 

of the fossils the ribs on the later whorls of large shells 

are more subdued and more closely spaced than on 

Recent shells of the same size; but this character is not 

uniform, and the variation apparently is not determined 

by the condition of the material. On the holotype of 

angelensis and on other specimens from the Third 

Street tunnel the ribs are hardly more closely spaced 

than on some modern shells (pi. 5, fig. 22); on others 

from this lot they are more subdued and more closely 

spaced (pi. 5, fig. 23). A moderately large specimen 

from Union Oil Co. Callender No. 22, Dominguez field, 

depth 4,146 feet, has exceptionally subdued ribs (pi. 

5, fig. 21); a fragment of a moderately large shell from 

Standard Oil Co. Baldwin No. 74, Montebello field, 

depth 1,955 to 1,975 feet, had strong widely spaced 

ribs. Small shells have strong ribs of varying spacing. 

Relatively strong varices are absent on the fossils, a 

condition possibly due to poor preservation, for the 

relative prominence of a varix may be altered by 

flattening along the varix. Better material may show 

characters to differentiate angelensis, or it may show 

that different forms are represented at different horizons. It is doubtful, however, whether better material 

will be forthcoming, as these thin shells are almost 

certain to be deformed by compaction of the sediments. 

Some specimens that are compressed in a plane at right 

angles to the long axis have assumed a grotesque 

outline.

F. oregonensis is recorded from many Pliocene 

localities,5 including the Ventura Basin6 and the Puente 

Hills.7 Arnold cited Priene oregonensis var. angelensis 

from the Pliocene of Elsmere Canyon,8 near Camulos,9 

and the Puente Hills. 10 No specimens of Fusitriton 

are now recognized in the collection from Elsmere 

Canyon. Seven poorly preserved specimens collected

< Redfield, J. H., Description of some new species of shells: New York Lyceum 

Nat. History Annals, vol. 4, pp. 165-166, pi. 11, figs. 2a, 6, 1848 (as Triton; Straits of 

St. Juan de Fuca, Oregon).

« See Grant, U. S., IV, and Gale, H. R., op. cit., p. 737.

«Merriam, J. C., in Watts, W: L., Oil and gas yielding formations of California: 

California State Min. Bur. Bull. 19, p. 222 Gist), 1901 (as Priene, Piru Creek and 

vicinity). For other Ventura Basin records see Grant and Gale, op. cit., p. 737, who 

figured a specimen with relatively strong varices from the upper Pliocene of Sulphur 

Canyon.

' Merriam, J. C., in Watts, W. L., idem, p. 222 (list, as Priene aff. P. oregonensis).

» Arnold, Ralph, op. cit., p. 526 (list). Arnold, Ralph, in Eldridge, G. H., and 

Arnold, Ralph, op. cit., p. 25 (list).

 Idem, p. 24 (list).

»Idem, p. 107 Olst).
24 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

by Eldridge in the Puente Hills (locality 3907, Olinda 

Hill, south of western wells of Fullerton Consolidated 

Oil Co.) seem to be more uniformly similar to the 

Recent oregonensis in strength and spacing of ribs, and 

one has two strong varices near the outer lip. It is not 

known whether this collection represents the Repetto 

formation or a higher Pliocene horizon. According to 

Martin's figure, some specimens from the Los Angeles 

Basin resemble the incomplete shell from Lawson's 

Wildcat series of the Eel River Basin in northern 

California (Pliocene) that served as the type of 

Argobuccinum scotiaensis Martin. 11

F. oregonensis is represented in the. collections of the 

National Museum from localities extending from Bering 

Sea to San Nicolas Island,. California. Dall 12 gave the 

range as "from the line of floating ice in winter in Bering 

Sea near the Pribiloff Islands, south on the west to the 

Okhotsk Sea and Japan, and on the east to San Nicolas 

Island, California; San Diego in deeper water (Raymond)." There are no large shells in the National 

Museum from localities south of Puget Sound; the 

largest one south of that region was dredged at a depth 

of 1,081 to 1,100 fathoms off San Nicolas Island (no. 

210537; length (tip broken) 72 millimeters, width 41 

millimeters). A fragment from the Third Street tunnel 

indicates a size about as large as the largest Recent 

shells. Of the 50 lots from Alaskan waters, 31 have 

depth records ranging from 6 to 230 fathoms. Southward along the coast of Washington, Oregon, and California the shells were dredged at depths of 40 to 1,081 

(to 1,100) fathoms, with the exception of two young 

shells from Monterey that have no depth record.

Grant and Gale 13 stated that Ranella (Priene") cancellata (Lamarck) 14 may be the proper name for oregonensis. This matter was discussed many years ago

" Martin, Brace, Descriptions of new species of fossil Mollusca from the later 

marine Neocene of California: California Univ., Dept. Geology, Bull., vol. 8, pp. 

192-193, pi. 21, fig. 3, 1914. ;

" Dall, W. H., Summary of the marine shell-bearing mollusks of the northwest 

coast of America: IT. S. Nat. Mus. Bull. 112, p. 141, 1921.

'3 Grant, U. S., IV, and Gale, H. R., op. cit., p. 737.

n Lamarck, Tableau encyclope'dique et mfithodique, Mollusques et polypes divers, 

pi. 415, fig. 1 (unnamed; Liste, p. 4, 1816 (as Triton)). [I have not seen the "Liste" 

cited by Sherborn (Index animalium, 1801-50, p. 1034,1921). The "Liste des objects 

repr6sent6s dans les planches de cette livraison" (Sherborn, C. D., and Woodward, 

B. B., On the dates of the 'Encyclop6die m6thodique' (Zoology): Zool. Soc. London 

Proc., 1893, p. 584) is not in either of two copies of this part of the Encyclopedic at the 

National Museum. Perhaps it was issued with some other part published at about 

the same time.] Lamarck, Histoire naturelle des animaux sans vertebres, vol. 7, 

p. 187, 1822 (as Triton; mers de 1'AmGrique mdridionale).

by Von Martens, 15 Lischke, 16 and Dall, 17 all of whom 

considered the two species well differentiated. Dall 

pointed out that Lamarck cited South America for 

Triton cancellatum and that a species agreeing with his 

figure is represented in the National Museum by specimens from Patagonia (Cape Horn and vicinity).

Triton cancellatum is the originally designated type of 

Fusitriton Cossmann, 18 characterized by a relatively 

long canal, heavy parietal denticle, and relatively weak 

varices. F. cancellatus and F. oregonensis are closely 

allied, though separated by a gap of several thousand 

miles. In California paleontologic literature oregonensis is generally assigned to Argobuccinum or Priene. 

Argobuccinum dates from Herrmannsen's usage 19 and 

need not be compared with Fusitriton; Argobuccinum 

Morch,20 the usage followed in many accounts of California fossils, is a homonym. Priene H. and A. Adams 21 

has a short canal, denticulate inner lip, and lirate outer 

lip. Cryotritonium Von Martens 22 appears to be the 

same genus as Fusitriton. Von Martens' publication 

bears the date 1903 on the title page, but according to 

a notation by Dall on his separate, Thiele received his 

copy January 30, 1904, and the publication was issued 

in the later part of January 1904. It was included in 

the 1903 issue of the Zoological Record, and the date 

1903 is assigned to Cryotritonium in the Index zooiogicus, 

No. II. Cossmann's publication bears the date December 1903.

F. oregonensis is recorded as a Pliocene and Recent 

species in Japan,23 and the genus is recognized in New 

Zealand.24

» Von Martens, E., Conchylien aus Alaska: Malakozool. Blatter, vol. 19, pp. 80-82, 

1872.

16 Lischke, C. E., Japanische Meers-Conchylien, pt. 2, pp. 166-167, 1871; pt. 3, pp. 

31-32, 1874.

17 Dall, W. H., Report on Bering Island Mollusca collected by Mr. Nicholas Grebnitzki: U. S. Nat. Mus. Proc., vol. 9, pp. 212-214, 1886.

1 8 Cossmann, M., Essais de paleoconchologie comparee, pt. 5, p. 109,1903.

" Hermannsen, A. N., Indicis generum malacozoorum, pt. 1, p. 77,1846 (cited as of 

Klein). Originally designated type, Ranella argus Linnfi [Murex argus Gmelin], 

Recent, "India."

2° Morch, O. A. L., Yoldi catalog, p. 105,1852 (cited as of Klein).

21 Adams, Henry, and Adams, Arthur, The genera of Recent Mollusca, vol. 2, p. 

654, 1858. Subsequently designated type (Cossmann, op. cit., p. 109), Triton scaber 

King, Recent, Chile.

« Von Martens, in Von Martens and Thiele, Die beschalten Gastroppden der deutschen Tiefsee-Expedition, pt. A, pp. 38, 40, 1903 [1904?]. Monotype, Tritonium 

(Cryotritonium) murrayi (E. Smith) (Lampusia (Priene) murrayi Smith), Recent. 

Cape of Good Hope.

» For citations see Grant, U. S., IV, and Gale, H. R., op. cit., pp. 737-738.

24 FinJay, H. J., A further commentary on New Zealand molluscan systematics: 

New Zealand Inst. Trans., vol. 57, p. 399,1926.
MOLLUSKS 

Specimens of Fusitriton aff. F. oregonensis (Redfield) from Repetto formation examined

25

.Locality Specimens Locality Specimens

Third Street tunnel, Los Angeles; Homer Hamlin. U.S. 

G. S. locality 3426.

100 feet northeast and 90 feet 

northwest from northeast 

corner of Second and Hill 

Streets, Los Angeles; about 

4 feet above level of Hill 

Street; W.H.Holman. U.S. 

G. S. locality 13862.

Standard Oil Co. Temple No. 

19, Montebello field, depth 

1,265 feet. U. S. G. S. locality 13869.

Standard Oil Co. Baldwin No. 

74, Montebello field, depth 

1,955 to 1,975 feet. U.S.G.S. 

locality 13865.

Holotype of oregonensis angelensis and 10 other broken 

and deformed specimens, 2 

of which are figured.

Broken, crushed specimen of 

medium size, sculptured with 

strong, widely spaced ribs.

Broken, crushed, slender specimen of medium size, sculptured with strong ribs. Apparent sutural collar probably due to telescoping.

Fragment of large specimen 

sculptured with moderately 

strong ribs; fragment of 

canal.

Union Oil Co. Sansinena No.

11, SE>4 sec. 30, T. 2 S./ R.

10 W., Puente Hills, depth

818 feet. Collection of

Union Oil Co. 

Standard Oil Co. Emery No.

52, West Coyote field, depth

3,625 to 3,626 feet. U. S. G. S.

locality 13878. 

Same well, depth 3,653 feet.

U. S. G. S. locality 138786.

Same well, depth 3,663 feet. 

U. S. G. S. locality 13878c.

Union Oil Co. Callender No. 

22, Dominguez field, depth 

4,146 feet. U.'S. G. S. locality 13895.

3 broken, crushed specimens of 

medium size.

Small, poorly preserved, slender (crushed?) specimen; 

fragment of small specimen.

Small, broken, slender specimen with sculptured widely 

spaced ribs.

Fragment of specimen of medium size.

Incomplete large crushed specimen- sculptured with exceptionally subdued ribs 

(figured).

Family "NASSIDAE"

Genus "NASSA Lamarck"

"Nassa" hamlini Arnold

Plate 5, figure 16

Nassa hamlini Arnold, U. S. Nat. Mus. Proc., vol. 32, pp. 527 

(list), 537-538, pi. 50, fig. 9, 1907. Third Street tunnel, 

Los Angeles; probably middle Fernando formation, lower 

Pliocene.

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 

309, pp. 152 (list), 252, pi. 40, fig. 9, 1907. Third Street 

tunnel, Los Angeles; Fernando formation, lower Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 

43, p. 1058 (Arnold's list), 1932 (1933). Third Street 

tunnel, Los Angeles; middle Pliocene.

Nassarius (Uzitd) hamlini (Arnold) Grant and Gale, San Diego 

Soc. Nat. History Mem., vol. 1, p. 678, 1931.

Nassarius (tUzita) hamlini (Arnold) Grant, in Soper and Grant, 

Geol. Soc. America Bull., vol. 43, p. 1058 (list), 1932 

[1933]. Third Street tunnel, Los Angeles; middle Pliocene (Arnold's record).

A moderately slender "Nassa" of medium size. 

Apex blunt. Sculpture consisting of narrow widely 

spaced ribs (11 on body whorl of holotype, not including varix at outer lip) and narrow weak spiral threads 

(4 on penultimate whorl of holotype) that override th'e 

ribs in subdued form. Outer lip varicose, the interior 

smooth. Canal not known. Parietal wall bearing a 

denticle. Siphonal fasciole bordered by a shallow 

groove. Length (incomplete) 15.4 millimeters, width 

8.7 millimeters (holotype).

This species is readily recognized by its sculpture. 

The typo is the only specimen in the Third Street

tunnel collection. A young shell from the Hollenbeck 

well in Los Angeles (in Hollenbeck Park approximately 

on Boyle Avenue, according to Hamlin's manuscript 

map) was identified by Arnold as hamlini. Inasmuch 

as tliis shell has retractive ribs, the identification is 

considered doubtful. The core specimens are poorly 

preserved. In addition to this material, four imperfect 

specimens collected from the transition zone between 

the Repetto and Pico formations in the Repetto Hills 

at locality 13614 are identified as hamlini. They show 

12 or 13 ribs on the body whorl and 4 or 5 spirals on the 

penultimate whorl and are a little larger than the type 

(incomplete length 18.3 millimeters, width 10.5 millimeters) . Eight other specimens from this locality, 

mostly molds that have a little shell material, may 

represent this species.

"Nassa" hamlini is characterized by subdued sculpture, varicose outer lip, and by the absence of lirations 

or wrinkles on the inner lip and on the interior of the 

outer lip. Though the type appears to be an adult 

shell, the interior of the outer lip is quite smooth. 

No fossil or living species similar to hamlini has been 

found in California, and this species may be a useful 

indicator of the Repetto or the transition zone between 

the Repetto and Picp. Perhaps hamlini is most closely 

allied to Nassa townsendi Dall,25 the type and only 

specimen of which was dredged near the Galapagos 

Islands at a depth of 812 fathoms. The edge of the

« Dall, W. H., Preliminary report on the collection of Mollusca and Brachiopoda 

obtained in 1887-88 [Albatross Kept.]: U. S. Nat. Mus. Proc., vol. 12, pp. 326-327, 

pi. 12, fig. 9, 1889.
26 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

outer lip is broken on this specimen, but the interior is 

smooth; the inner Up is smooth; and the posteriormost 

two spirals are stronger than in hamlini. Alectrion 

goniopleura 'Dall,28 from a depth of 633 fathoms near 

the Galapagos Islands, evidently is closely allied to 

townsendi, but the only specimen is a small defective 

shell that differs in sculpture from that species.

Nassarius Dumeril is of doubtful validity as a substitute name for the Lamarckian Nassa, as was recognized 

when it was recently used.28 But it is to be regretted 

that Nassarius was used, as Pilsbry and Lowe's claim 

that it is to be used for the group of Buccinum arcularia 

Linne appears to be well founded.29 It is not known to 

what genus of nassid. gastropods "N." hamlini belongs.

Specimens of "Nassa" hamlini from Repetto formation examined

Locality Specimens

Third Street tunnel, Los Angeles; Homer Hamlin. U. S. G. S. locality 

3426.

Standard Oil Co. Emery No. 52, West Coyote field, depth 3,695 feet. 

U. S. G. S. locality 13878d.

Union Oil Co. Bell No. 69, Santa Fe Springs field, depth 3,642 feet. Collection of Union Oil Co.

Ohio Oil Co. Recreation No. 1, Playa del Rey field, depth 3,821 feet. 

Collection of Union Oil Co.

Holotype.

A poorly preserved crushed specimen (figured).

2 poorly preserved specimens.

A poorly preserved specimen.

Specimens of "Nassa" hamlini from other horizons examined

Repetto Hills, slope on west side of Atlantic Boulevard, 0.33 mile S. 32° 

E. from 735-foot triangulation station between Garvey Avenue and 

Atlantic Boulevard; W. P. Woodring and Alex Clark. U. S. G. S. 

locality 13614. Transition zone between Repetto formation and Pico 

formation.

4 incomplete specimens and 8 poorly preserved specimens (identification of latter doubtful).

Family NEPTUNEIDAE?

Genus PIICIFUSTTS Dall? 

Plicifusus? sp.

Plate 5, figure 18

'Pleurotoma sp. undet., Arnold, U. S. Nat. Mus. Proc., vol. 32, 

p. 527 (list), 1907. Third Street tunnel, Los Angeles; 

middle Fernando formation, lower Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 

43, p. 1058 (Arnold's list), 1932 [1933]. Third Street 

tunnel, Los Angeles; middle Pliocene.

Pleurotoma sp. indet., Arnold, in Eldridge and Arnold, U. S. 

Geol. Survey Bull. 309, p. 152 (list), 1907. Third Street 

tunnel, Los Angeles; Fernando formation, lower Pliocene.

An incomplete crushed specimen in the Third Street 

tunnel collection, evidently Arnold's Pleurotoma, has a 

length (incomplete) of 47.2 millimeters, and a width 

(modified by compression) of 29.9 millimeters. The 

growth lines are misleading in the figured view, as the 

part of the body whorl adjoining the suture is telescoped 

and broken. A small area on the opposite side shows 

that the lines bend forward near the suture.. Faint 

ribs are visible on. the penultimate whorl. This shell 

is probably neptuneid and may represent the genus 

Plicifusus Dall,27 a few species of which reach the 

California coast in deep water.

A poorly preserved crushed shell from Union Oil Co. 

Callender No. 17, Dominguez field, depth 5,463 feet,

" Dall, W. H,, The Mollusca and the Brachiopoda [Albatross Kept.]: Harvard 

College Mus. Comp. Zoology Bull., vol. 43, pp. 308-309, 1908.

» Dall, W. H., Illustrations and descriptions of new, unflgured, or imperfectly 

known shells, chiefly American, in the U. S. National Museum: U. S. Nat. Mus. 

Proc., vol. 24, p. 623,1902 (as subgenus of Tritonofiatu). Originally designated type, 

Fuiut kroyeri Moller, Recent, north Atlantic, circumboreal.

may represent another neptuneid form. It shows some 

indication of spiral sculpture.

Family BUCCINIDAE?

Genus BUCCINUM LinnS?

Buccinum? sp.

Plate 5, figure 15

Bwccinum sp. undet., Arnold, U. S. Nat. Mus. Proc., vol. 32, 

p. 527 (list), 1907. Third Street tunnel, Los Angeles; 

middle Fernando formation, lower Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43, 

p. 1058 (Arnold's list), 1932 [1933]. Third Street tunnel, 

Los Angeles; middle Pliocene^

Buccinum sp. indet., Arnold, in Eldridge and Arnold, U. S. Geol. 

Survey BuU. 309, p. 152 (list) 1907. Third Street tunnel, 

Los Angeles; Fernando formation, lower Pliocene.

Buccinum sp., Gale, in Grant and Gale, San Diego Soc. Nat. 

History Mem., vol. 1, p. 40 (discussion), 1931.

The incomplete deformed specimen from the Third 

Street tunnel identified.by Arnold as Buccinum probably 

represents that genus. The length (incomplete) is 

42.8 millimeters, and the width (modified by deformation) 25.6 millimeters. The whorls have a strong 

.sutural constriction. In outline this specimen resembles 

the round-shouldered form of Buccinum viridum Dall,30

»s Woodring, W. P., Miocene mollusks from Bowden, Jamaica; pt. 2, Gastropods 

and discussion of results: Carnegie Inst. Washington Pub. 385, pp. 264-265, 1928. 

See this discussion for citations.

» Pilsbry, H. A., and Lowe, H. N., West American and Central American mollusks collected by H. N. Lowe, 1929-31: Philadelphia Acad. Nat. Sci. Proc., vol. 84, 

p. 68,1932.

«o Dall, W. H., Preliminary report on the collection of Mollusca and Brachiopoda 

obtained in 1887-88 [Albatross Kept.]: U. S. Nat. Mus. Proc., vol. 12, p. 320, pi. 6, 

fig. 9,1889.
MOLLUSKS 27

which ranges down the coast from Alaska and has been 

dredged at depths of 236 to 795 fathoms off California. 

The fossil apparently is more slender, and no spiral 

sculpture is discernible.

Family SOLEMYACIDAE

Genus SOLEMYA Lamarck

Subgenus ACHARAX Dall

Solemya (Acharax) aff. S. johnsoni Dall

Plate 5, figure 14

An *Acharax of medium size with the opisthodetic 

ligament preserved. Posterior part of shell sculptured 

with weak, closely spaced radial ribs and shallow 

grooves; part extending down from umbonal region 

sculptured with very weak ribs and grooves; anterior 

part sculptured with an indeterminate number (4 on 

preserved part of left valve) of strong grooves bearing a 

midrib. On the left valve the first groove from the 

umbonal region is relatively weak and the midrib is 

faint; on the others the groove and midrib are strong. 

On the right valve the first groove is relatively weak and 

the midrib is wide and low; on the second groove the 

midrib is not quite so strong as on the left valve; and 

the other grooves are not preserved. Posterior end 

bearing coarse irregular concentric ripples.

Restored length about 45 millimeters, height 15.8 

millimeters.

The genus Solemya is represented by the greater part 

of a paired gaping shell. The valves are slightly 

sheared except where they are held together by the 

ligament. This specimen was obtained from Standard 

Oil Co. Baldwin No. 73, Montebello field, at a depth of 

3,340 to 3,358 feet (U. S. G. S. locality 13864). The 

upper edge of the proximal part of the thick ligament is 

broken, and part of the right valve is broken away.

The type lot of Solemya johnsoni Dall 31 is from 

Albatross station 3010 (off California, 1,005 fathoms), 

the only locality mentioned in the original description. 

I am indebted to Dr. J. P. E. Morrison for searching 

the alcoholic collection in the National Museum for the 

material from this locality, which was not included in 

the catalog of the alcoholic collection. The material 

from locality 3010, labeled johnsoni in DalTs writing, 

consists of four paired shells that have a virtually 

intact periostracum. One that appears to agree with 

the figure is regarded as the holotype. The valves of 

this specimen are cracked, and a small part of the 

anterior end of the periostracum is missing. This 

shell has a length including the periostracum of about 

112 millimeters. A lot of three paired shells, two of

" Dall, W. H., On some new or interesting West American shells obtained from the 

dredgings of the U. S. Fish Commission steamer Albatross in 1888, and from other 

sources: U. S. Nat. Mus. Proc., vol. 14, p. 189,1891; Report on Mollusca and Brachiopoda dredged in deep water, chiefly near the Hawaiian Islands, with illustrations of 

hitherto unflgured species from Northwest America: U. S. Nat. Mus. Proc., vol. 17, 

pp. 712-713, 731, pi. 25, flg. 1, 1895.

which have the periostracum intact, from Albatross 

station 3399 (off northern Ecuador, depth. 1,740 

fathoms) is labeled "types" of johnsoni in DalTs 

writing (alcholic collection No. 3175). The largest of 

these shells has a length including the periostracum of 

about 73 millimeters. Later it was claimed that 

S. johnsoni was described from a specimen collected off 

the coast of Oregon.32 Solemya agassizi Dall,33 which 

was given a range from the Gulf of California to Peru, 

was differentiated from johnsoni on the grounds that it 

has 6 or 7 anterior radial channels, as compared with 

9 to 12 on S. johnsoni, and that the periostracum of 

johnsoni has a subtriangular outline. The type of 

agassizi is a large shell (U. S. Nat. Mus. 106885) that 

has a length exclusive of the periostracum of about 

143 millimeters and was dredged off Panama at a depth 

of 1,672 fathoms. The basal part has been broken 

since the drawing was made, or the drawing is a restoration. The anterior part of the shell has six grooves; 

some sculpture on the umbonal part of the shell is not 

shown on the drawing. It appears doubtful whether 

two species are represented in the National Museum 

coUections. All the specimens in the dried collection, 

representing localities from Oregon to Ecuador, are 

labeled agassizi in Dall's writing, or were so labeled 

under his direction. They have five or six grooves 

bordered by flat or slightly raised edges, but on some 

there is a transition from deep grooves to shallow 

grooves and ribs, and the number of grooves is a matter 

of' individual judgment. No specimen has the entire 

periostracum preserved. The specimens in the type 

lot of johnsoni have seven distinct grooves; those from 

station 3399 have seven to nine.

In some of the specimens labeled agassizi the central 

part of the groove is inflated but does not form a distinct midrib as on the fossil from the Los Angeles Basin: 

More specimens are needed to determine the significance of the midrib; it apparently is not so strong on 

the right valve.

Solemya has been recorded from the Pliocene of the 

Eel River Basin, in northern California,34 but this is 

the first record in the southern California Pliocene. 

Solemya ventricosa Conrad 36 was described at an early 

date from the Miocene of Astoria, Oreg. Figure 7 

appears to have been based on a large, paired, gaping 

specimen (U. S. Nat. Mus. 3567) on which the greater 

part of the right valve has a thin layer of shell material. 

The mineralized ligament is preserved. The specimen 

does not entirely agree with the figure, as the extreme 

posterior end is missing and more of the lower part

"Dall, W. H., The Mollusca and the Brachiopoda [Albatross Kept.]: Harvard 

College Mus. Comp. Zoology Bull., vol. 43, pp. 365-366,1908.

" Idem, pp. 365-366, pi. 16, flg. 10.

84 Martin, Bruce, The Pliocene of middle and northern California: California 

Univ., Dept. Geology, Bull., vol. 9, pp. 238 Gist), 240 (list), 254 (list), 1916 (as Solemya 

 ventricosa Conrad).

'»Conrad, T. A., in Dana, J. D., U. S. Exploring Expedition, Geology, p. 723^ 

pi. 17, figs. 7, 8, 1849.
28 LOWER PLIOCENE MOLLUSKS AND ECHI NOIDS FROM LOS ANGELES BASIN

below the umbonal region is preserved. The whole 

rock mass has been broken up and part of it glued 

together. The sculpture on the anterior part of the 

shell is not so strong as on the figure, and the number of 

grooves is indeterminable. The specimen under U. S. 

Nat. Mus. 3486 closely agrees with figure 8, aside from 

a small upper posterior part that is missing. Donax? 

protexta Conrad 36 (U. S. Nat. Mus. 3613) is probably 

a mold of a small Solemya, as Woodward,37 Meek,38 

and Dall 39 concluded, probably a small S. ventricosa. 

Tegland 40 identified as ventricosa a relatively high form, 

higher than Conrad's specimens, from the Miocene of 

Washington. A Solemya from the upper Oligpcene of 

Washington has been described as S. dalli Clark,41 and 

the genus has been recognized in the California Eocene.42 

The relations of the subgenera of Solemya were discussed by Dall. In Solemya s. s. 43 a narrow internal 

arm of the ligament extends in front of the chondrophore; in the subgenus Acharax 44 the ligament is 

thicker and wholly external, and the sculpture is 

stronger.

Family NUCUIIDAE

Genus ACIIA H. and A. Adams

Subgenus ACILA s. s. 

Acila (Acila) semirostrata (Grant and Gale)

Plate 5, figures 10, 11

Nucula (Acila) semirostrata Grant and Gale, San Diego Soc. Nat. 

History Mem., vo}. 1, pp. 113-115, figs. 2a, 2b, 3a, 3b, 

1931. Near San Martinez Grande Canyon; middle 

Pliocene.

Acila (Acila) semirostridta (Grant and Gale) Schenck, Mus. 

royale histoire nat. Belgique, vol. 11, no. 14, p. 4, table, 

1935; Geol. Soc. America Special Paper 4, p. 94, pi. 13, 

figs. 2, 8, 10, text fig. 8, 1936.

S8 Conrad, T. A., in Dana, J. D., op. cit., pp. 723-724, pi. 17, fig. 9.

*' Woodward, S. P., in Carpenter, P. P., Report on the present state of our knowledge with regard to the Mollusca of the west coast of North America; British Assoc. 

Adv. Sci. Kept, for 1856, p. 367, 1857.

38 Meek, F. B., Check list of the invertebrate fossils of North America;'Miocene: 

Smithsonian Misc. Coll., no. 183, p. 30, 1864.

ao Dall, W. H., The Miocene of Astoria and Coos Bay, Oregon: U. S. Geol. Survey 

Prof. Paper 59, p. 101, 1909.

M Tegland, N. M., The fauna of'the type Blakeley upper Oligocene of Washington: 

California Univ., Dept. Qeol. Sci., Bull., vol. 23, pp. 102-103, pi. 4, figs. 11, 12, 1933.

41 Clark, B. L., Pelecypoda from the marine Oligocene of western North America: 

California Univ., Dept. Qeol. Sci., Bull., vol. 15, p. 73, pi. 22, fig. 3, 1925. Tegland, 

N. M., op. cit., pp. 103-104, pi..4, figs. 1-10.

« Clark, B. L., and Woodford, A. O., The geology and paleontology of the type 

section of the Meganos formation (lower middle Eocene) of California: California 

Univ., Dept. Qeol. Sci., Bull., vol. 17, p. 85, pi. 14, fig. 1, 1927. According to Clark 

and Woodford, there is an earlier record of the genus from the Eocene of the Pacific 

coast, which I have not found.

43 Lamarck, Histoire naturelle des animaux sans vertebres, vol. 5, pp. 488-489, 

1818. Subsequently designated type (Children, J. Q., Lamarck's genera of shells: 

Quart. Jour. Sci., vol. 14, p. 300,1823; quoted from Kennard, A. S., Salisbury, A. E., 

and Woodward, B. B., The types of Lamarck's genera of shells as selected by J. Q. 

Children in 1823: Smithsonian Misc. Coll., vol. 82, no. 17, p. 7, 1931), Solenomya 

mediterranea Lamarck [emendation for Solemya] [= Tellina togata Poll, fide Bucquoy, 

E., Dautzenberg, Ph., and Dollfus, G., Mollusques marins du Roussilon, vol. 2, 

p. 718, 1898; = Mytilus solen von Salis Marschlins, fide Dall, W. H., op. cit., p. 362, 

1908], Recent, Mediterranean.

« Dall, W. H., A revision of the Solenomyacidae: Nautilus, vol. 22, p. 2, 1908; 

The Mollusca and the Brachiopoda [Albatross Rept.]: Harvard College Mus. Comp. 

Zoology Bull., vol. 43, p. 364,1908. Originally designated type, S. johnsoni Dall.

A moderately large, short Acila. Posterior end truncated, slightly prolonged at the ventral margin. Posterior sinus moderately strong. The apex of the main 

chevron extends downward in an arc from the umbo. 

An inverted chevron lies in the posterior sinus, and a 

minor chevron on the rostrum bacfci of the sinus.

Length 22 millimeters, height 18.5 millimeters.

A flattened right valve from Wilmington Terminal 

Oil Co. Banning No. I, Wilmington field, depth 3,265 

feet (U. S. G. S. locality 13916), has the outline of semirostrata. Most of the shell is on the impression. The 

inverted chevron in the sinus and the minor chevron 

behind it are not mentioned in the. original description 

and do not show on the figure, but Schenck described 

"secondary bifurcation especially noticeable on disk 

posterior to sinus." - The Recent Japanese .'A. mirabilis 

(Adams and Reeve)45 has an inverted chevron and minor 

chevron, but large specimens have a double or multiple 

main chevron. This species also is larger, more elongate, 

and more strongly rostrate than semirostrata.

Acila s. s. 46 appears in the Oligocene of the Pacific 

coast, and semirostrata is the latest species known there. 

This species appears to range from the Repetto formation into the Pico formation. Poorly preserved specimens agreeing in outline with semirostrata occur in the 

transition zone between the Repetto and Pico formations in the Repetto Hills (locality 13616, west side of 

valley between Atlantic Boulevard and Garvey Avenue, 

0.32 mile S. 30° W. from 735-foot triangulation station). 

Specimens collected from a concretion in the Pliocene 

sandy silt unconformably underlying Pleistocene foramiriiferal sand on the east side of Newport Lagoon are 

similar to semirostrata, as I remember them, but the 

collection has been mislaid. The Pliocene silt at this 

locality carries a meager foraminiferal fauna of Pico 

aspect, according to a communication from Mr. D. D. 

Hughes.

There appears to be no reasonable doubt that Nucula 

divaricata Hinds belongs in the rostrate division of Acila. 

Hinds' figure represents a small shell with an indistinct 

rostrum and sinus. Schenck and other workers considered mirabilis conspecific with divaricata, but apparently small shells from the type region of divaricata have 

not been available for comparison with young shells of 

mirabilis. The smallest specimen of mirabilis in the 

collections of the National Museum (length 15 millimeters) is larger than Hinds' figure and has a more 

extended posterior end. On the ground that divaricata 

was described as having 22 to 24 posterior [anterior] 

teeth, Hanley 47 considered the two forms distinct.

45 Adams, A., and Reeve, L., Zoology of the voyage of H. M. S. Samarang; Mollusca, p. 75, pi. 21, fig. 8, 1850 (as Nucula).

« Adams, H. and A., The genera of Recent Mollusca, vol. 2, p. 545, 1858. Subsequently designated type (Stoliczka, Cretaceous fauna of southern India, vol. 3, p. 

325, 1871), Nucula divaricata Hinds, Recent, China Sea.

*' Hanley, Sylvanus, Monograph of the family Nuculidae (Sowerby's Thesaurus 

conchyliorum), p. 155, 1860.
MOLLUSKS 29

Subgenus TRUNCACILA Schenck? 

Acila? (Truncacila?) cf. A. castrensis (Hinds)

Plate 5, figure 20

A right valve from Union Oil Co. Farwell No. 17, 

Santa Fe Springs field, depth 5,631 feet (U. S. G. S. 

locality 13885), appears to be similar to Acila castrensis. 

The abrupt posterior truncation and the rather pointed 

anterior end may be due to deformation. The inner 

shell material is preserved. The corresponding impression, which should show the sculpture, apparently was 

not available. A shallow groove extending downward 

in an arc from the umbo probably marks the apex of 

the chevron. Indistinct, almost vertical markings are 

visible at one place behind the groove, but it is improbable that they represent sculpture. The length is 13 

millimeters; the height 9.7 millimeters.

A. castrensis has been identified in the Pliocene beds 

at Elsmere Canyon and Pico Canyon 48 and in the beds 

near Holser Canyon assigned by Grant and Gale to the 

middle Pliocene; 40 and a form similar to castrensis has 

been described from the lower Pliocene on the south 

slope of Sulphur Mountain. 50 A. castrensis now ranges 

from Bering Sea to San Diego, and the lots in the 

National Museum have depth records of 8 to 688 

fathoms. This species is the type of the subgenus 

Truncacila,51 which lacks the posterior sinus and rostrum of Acila s. s. The differentiation is not well 

marked in some fossil species.

Family ARCIDAE

Genus ANADARA Gray

Anadara camuloensis (Osmont)

Plate 6, figures 10, 13-16

Area n. sp. (a) Merriam, in Watts, California State Min. Bur. 

Bull. 19, p. 220 (list), 1900 (fide Osmont). Puente Hills, 

Piru Creek and vicinity; middle Neocene.

Area camuloensis Osmont, California Univ., Dept. Geology, 

Bull., vol. 4, p. 98, pi. 10, pi. 11, figs. 6b, 6c, 1905. Near 

Camulos and in foothills of Santa Ana Mountains; 

probably Pliocene (p. 100).

Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 543, pi. 47, figs. 1, 

la, Ib (after Osmont; said to be holotype), 1907. Near 

Camulos; Fernando formation, lower Pliocene or upper 

Miocene.

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 

309, pp. 24, 246, pi. 37, figs. 1, la, Ib (after Osmont; said 

to be type), 1907. Near Camulos; lower part of Fernando formation.

"English, W. A., The Fernando group near Newhall, Calif.: California Univ., 

Dept. Geology, Bull., vol. 8, p. 210, 1918 (as Nucula). Grant, U. S., IV, and Gale, 

H. 11., Catalogue of the marine Pliocene and Pleistocene Mollusca of California: San 

Diego Soc. Nat. History Mem., vol. 1, p. 116,1931.

49 Osraout, V. C., Areas of the California Neocene: California Univ., Dept. Geology, 

Bull., vol. 4, p. 98, 1905. Grant, U. S., IV, and Gale, H. R., op. cit., p. 110.

»o Schenck, H. Q., op. cit. (1930), p. 98, pi. 14, figs. 2, 3.

«' Schonck, H. G., In Grant, U. S., IV, and Gale, H. R., op. cit., p. 115. Originally 

designated type.

English, California Univ., Dept. Geology, Bull., vol. 8, 

p. .209 (list), 1914. Holser Canyon; lower Fernando, 

Pliocene.

Smith, California Acad. Sci. Proc., 4th ser., vol. 9, pp. 150 

(list), 152 (list), 155 (list), 1919. Fernando, Pliocene.

Kew, U. S. Geol. Survey Bull. 753, p. 77 (list), 1924. Holser 

Canyon, between Holser Canyon and San Martinez 

Grande Canyon; Pico formation, Pliocene.

Area (Area) multicostata variety camuloensis Osmont. Grant 

and Gale, San Diego Soc. Nat. History Mem., vol. 1, 

pp.. 30 (discussion), 34 (discussion), 139, pi. 2, figs. 5a-c, 

1931. Holser Canyon and southeast of Pico Canyon 

(figured specimen); middle Pico, Pliocene.

Area multicostata Sowerby. Arnold, U. S. Geol. Survey Prof. 

Paper 47, pp. 91 (list), 95 (list, "?"), 116 (list), 123 (list), 

1906. Third Street tunnel, Los Angeles; Pliocene, probably lower. Puente Hills; lower Pliocene.

Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 527 (list), 1907. 

Third Street tunnel, Los Angeles; middle Fernando formation, lower Pliocene.

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 309, 

pp. 107 (list, "?"), 152 (list), 1907. Puente Hills; Fernando formation. Third Street tunnel, Los Angeles; 

Fernando formation, lower Pliocene.

Smith,'California Acad. Sci. Proc., 4th ser., vol. 9, pp. 152 

(list), 155 (list), 1919. Fernando, Pliocene.

English, U. S. Geol. Survey Bull. 768, p. 43 (Arnold's list), 

1926. Puente Hills; Fernando group, Pliocene.

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43, 

p. 1057 (Arnold's list) 1932 [1933]. Third Street tunnel, 

Los Angeles; middle Pliocene. 

Area (Area) multicostata Sowerby. Grant, in Soper and Grant,

idem (Arnold's record).

Not Area multicostata Sowei'by, Zool. Soc. London Proc., 1833, 

p. 21. Gulf of Tehuantepee; Recent.

A large, thick-shelled, moderately short Anadara. 

Sculpture consisting of strong ribs bearing heavy concentric ridges ("beads") that appear to be strongest on 

the anterior part of the shell and are not uniformly developed. Ribs and interspaces show indistinct radial 

threads. Cardinal area wide (from umbo to lower 

margin).

Restored length about 85 millimeters, restored height 

about 81 millimeters, diameter (right valve) about 45 

millimeters.

An incomplete right valve from the Third Street 

tunnel (pi. 5, figs. 14-16) and part of a right valve from 

A. T. Jergins Trust Robertson No. 1, Playa del Rey 

field, depth 3,830 feet (U. S. G. S. locality 13911; pi. 

5, figs. 10, 13) are identified as Anadara camuloensis. 

The shell of the outcrop specimen has a thickness of 

17 millimeters in the anterior-ventral region. The ribs 

over the greater part of the central region are worn, and 

the posterior half of the cardinal area also is worn, 

revealing the trace of the teeth. The core specimen is 

not so thick (12 millimeters) and is less inflated. The 

shell is bored and corroded, and the upper part is greatly 

worn. A thin layer of inner shell material covers the 

mold, which extends to the edge of the core in the 

lower posterior region, indicating that more of the
30 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

lower posterior part of the shell was present but was 

cut off by the core bit.

The Third Street tunnel specimen was identified by 

Arnold as Area multicostata, but the specimen of 

multicostata that Arnold figured, as stated in the 

explanation of the plate, is a Recent shell from San 

Diego (U. S. Nat. Mus. 12574). Anadara multicostata, 

which has a range from Balboa, Calif., to the Gulf of 

California,62 is not so thick-shelled and is more elongate (according to Osmont's figures); lacks the heavy 

ridges on the ribs; and generally has concentric grooves 

in the interspaces. The anterior ribs have ridges, or 

"beads", which are weaker than in camuloensis. They 

generally are confined to the umbonal part of the shell 

but may continue toward the margin of moderately 

large specimens. A. camuloensis may be a form of 

multicostata, as treated by Grant and Gale, but multicostata proper has not been certainly identified in the 

California Pliocene. There are no complete specimens 

of camuloensis in the National Museum. A well-preserved fragment of the lower anterior part of a left 

valve collected by Kew in the type region (locality 

8140, 2,223-foot hill on divide between Holser Canyon 

and San Martinez Grande Canyon) has heavy ridges 

on the ribs, relatively strong radial threads on the ribs 

and weak ones in the interspaces. The only specimens 

available from the Puente Hills (locality 3909, face of 

ridge north of Brea Canyon, opposite wells of Brea 

Canyon Oil Co.) are incomplete impressions of small 

ones (length about 35 millimeters), the most complete 

of which appears to be relatively elongate and therefore similar in outline to multicostata. It has in at 

least parts of the shell well-defined concentric grooves 

in the interspaces, as in multicostata, but the ridges 

on the ribs of the anterior half of the shell are stronger 

than in multicostata. This presumably is the material 

that Arnold identified as multicostata?, and it may be 

more similar to that form than to camuloensis. It is 

not known whether this collection represents the 

Repetto formation or a higher horizon.

Specimens of camuloensis that show the character of 

the umbo at an early stage are not available. Young 

shells of multicostata have a depression on the umbo, 

indicating a median byssal gape at an early stage. 

This depression, which may continue to a late stage, is 

found on every species of Anadara examined. Area 

grandis Broderip and Sowerby is a thick-shelled species 

that lives on the Pacific coast of Central America and 

northern South America and tolerates brackish water. 

A. grandis 55 and its allies in the Miocene of the West

" Grant, U. S., IV, and Gale, H. R., op. cit., p. 139. The type locality is cited by 

Sowerby as the Gulf of Tehuantepec.

 > Morch, O. A. L., Beitrage zur Molluskenfauna Central-Amerika's: Malakol. 

Blatter, vol. 7, p. 205,1861. Lamy, Edouard, Revision des Area vivants du Museum 

d'histoire naturelle de Paris: Jour. Conchyliologie, vol. 55, pp. 262-263, 1907.

Indies, Central America, and northern.South America 54 

have been referred to Senilia Gray. 55 Reinhart's 

objection to this arrangement 56 appears "to" be well 

founded. Young valves of grandis have a depression 

on the umbo, whereas on young valves of senilis a 

depression is absent on the strongly prosogyrate umbo. 

Senilia is considered a separate genus. Reinhart 

adopted the arrangement of placing Senilia as a subr 

genus under Anadara, though Senilia was proposed 5 

years earlier, and claimed that there is nothing in the 

International Rules of Zoological Nomenclature to 

prevent such action. Article 7 of the rules states that 

generic and subgeneric names "are coordinate that 

is, they are of the same value." Larkinia Reinhart 57 

was proposed for the American so-called Senilia. The 

type species is represented by fragments and one poorly 

preserved paired shell, part of Nelson's original material 

and labeled by him "cotypes", in the collections of the 

National Museum. It has an angular posterior ridge, 

a virtually central umbo, and a very wide cardinal area. 

The characters of the umbo at an early stage are undeterminable, and they have not been described. A. 

multicostata and camuloensis may belong to this minor 

division of Anadara, where they were placed by 

Reinhart.

The type designation of Area Linn6 58 has recently 

been considered by several writers. 59 Schumacher's 

designation 60 ("pour le type du genre j'ai donne" la fig. 2, 

PL XIX, de la charniere de VArca antiguata Lin. qu'on 

trouve figuree dans Chemn. 7, p. 201, Tab. 55, fig. 

548") is not entirely satisfactory. As contrasted with 

the use of the term "type" on pages 20, 148, and 173, 

it is doubtful whether the usage on pages 107, 108, 118, 

and 172 is to be regarded as a type designation. According to Schumacher's descriptions and figures, his 

advanced classification of pelecypods was based principally on the hinge, and he may have intended to figure 

the type of hinge in Area, not the type species of the 

genus. Area antiguata is not cited under any of the

« Woodring, W. P., Miocene mollusks from Bowden, Jamaica; pt. 2, Gastropods 

and discussion of results: Carnegie Inst. Washington Pub. 385, pp. 58, 70, 71, 79-80, 

84, 87, 1928. Olsson, A. A., Contributions to the Tertiary paleontology of northern 

Peru; pt. 5, The Peruvian Miocene: Bull. Am. Paleontology, vol. 19, no. 68, pp. 71-76, 

1932.

« Gray, J. E., Synopsis of the contents of the British Museum, ed. 44, p. 81,1842 

(genus without species). (Quoted from Iredale, Malacol. Soc. London Proc., vol. 

10, p. 308, 1913.) Tautonymic type designated by Gray (Zool. Soc. London Proc., 

1847, p. 198) Area senilis [Linnfi], Recent, West Africa.

»6 Reinhart, P. W., Classification of the pelecypod family Arcidae: Mus. royale 

histoire nat. Belgique Bull., vol. 11, no. 13, pp. 41-43,1935.

57 Idem, pp. 41-42. Originally designated type, Anadara larkinii (Nelson), Miocene, Peru.

" Linnfi, C., Systema naturae, ed. 10, pp. 693-695,1758.

" Stewart, R. B., Gabb's California Cretaceous and Tertiary type lamellibranchs: 

Acad. Nat. Sci. Philadelphia Special Pub. 3, pp. 83-86, 1930. Grant, U. S., IV, and 

Gale, H. R., op. cit., pp. 137-138,1931. Arkell, W. J., Monograph of British corallian 

Lamellibranchia, pt. 8, Pal. Soc. (vol. 88), pp. ii-iii, 1935. Reinhart, P. W., op. cit., 

pp. 14-17, 1935.

60 Schumacher, C. F., Essai d'un nouveau systeme des habitations des vers testacees, p. 172,1817.
MOLLUSKS

subdivisions of Area according to the method which, 

as pointed out by Stewart,61 Schumacher used to cite 

types, but perhaps the typical subdivision was not 

included. Even if Schumacher's designation is accepted, perhaps the International Commission on 

Zoological Nomenclature may waive the designation in 

view of the long-continued usage of Area noae Linne as 

the type of Area. My proposal of Diluvarca,62 which 

was based on a misconception of the characters of Area 

antiquata Linn6, the type species of Anadara,63 and on 

ignorance of the availability of other names, has been 

justly criticized.04 I soon abandoned Diluvarca as a 

synonym of Anadara,65 but it has been used by a 

few workers, and it will always remain an unnecessary burden.

The type of Area microdonta Conrad 66 is a wellpreserved right valve in the National Museum (no. 

1844), said to be from the "Tulare Valley(?)." Blake 

(op. cit., p. 188) cited the locality as "the hills of the 

Coast Mountains near the Tulares." The Kettleman 

Hills fit this description, and in these hills an Anadara 

that corresponds to Conrad's figure of Area trilineata 6/ 

is abundant. Area trilineata was said to have been 

collected by Newberry at Santa Barbara, but according 

to Newberry's itinerary he was nowhere near Santa 

Barbara, and this species has never been found near 

Santa Barbara. Area trilineata, Area canalis, and Mulinia densata, described at the same tune and said to 

have been collected at Santa Barbara by Newberry, 

may have been collected at some locality farther north 

in the coastal region of California. It is possible but 

unlikely that they were collected by Blake in the 

Kettleman Hills or nearby; Blake mentioned only the 

Area. The types of all three are lost, and, inasmuch as 

they have not been found at the alleged type locality, 

they are on an unsatisfactory footing. California fossils 

have been identified as Area microdonta, but no fossil or.

«' Stewart, R. B., op. cit., p. 33.

«! Woodrlng, W. P., Miocene mollusks from Bowden, Jamaica; Pelecypods and 

scaphopods: Carnegie Inst. Washington Pub. 300. pp. 40-41,1925. Originally designated type, Area diluvii Lamarck, Miocene to Recent, Mediterranean.

09 Gray, J. £., A list of the genera of Recent Mollusca, their synonyms and types: 

Zool. Soc. London Proc., 1847, p. 108. Originally designated type, Area antiguata 

ILInno].

8< Cox, L. R., Neogeno and Quaternary Mollusca from the Zanzibar Protectorate: 

Paleontology of Zanzibar Protectorate, p. 05, 1027. Stewart, R. B., op. cit., p. 86. 

Grant, U. S., IV, and Gale, H. R., op. cit., pp. 137-138.

oj Woodring, W. P., Miocene mollusks from Bowden, Jamaica, pt. 2: Carnegie Inst. 

Washington Pub. 385, p. 18, footnote, 1028.

"Conrad, T. A., in Blake, W. P., Preliminary geological report [Williomson's 

Reconnaissance in California], pp. 7 (list), 13, 1857. Conrad, T. A., Descriptions of 

the fossil shells: U. S. Pacific R. R. Expl., vol. 5, pt. 2, pp. 310 (list), 323-324, 352 

(list), pi. 3, flg. 29,1867.

87 Conrad, T. A., Descriptions of three new genera, twenty-three new species middle 

Tertiary fossils from California, and one from Texas: Acad. Nat. Sci. Philadelphia 

Proc., vol. 8, p. 314,1857; Description of the Tertiary fossils.collected on the survey: 

Q. S. Pacific R. R. Expl., vol. 0, pt. 2, p. 70, pi. 2, flg. 8, p. 85 (list). 1850 (?).

living species now known from California agrees with 

it, and whether it came from California is very doubtful. 

It shows no characters to differentiate it from "nonwinged" specimens of the Recent West Indian species 

identified by Dall as Area auriculata Lamarck. Perhaps 

Blake collected it from Pleistocene deposits on the 

Atlantic coast of Panama near Colon (Aspinwall of 

Blake's time), where the species identified as A. auriculata is known to occur. Blake collected from the 

Miocene Gatun formation, but nothing is mentioned 

about other localities in Panama.

Family LIMOPSIDAE 

Genus IIMOPSIS Sassi

Subgenus FELICIA Mabille and Rochebrune 

Limopsis (Felicia) phrear Woodring, n. sp.

Plate 5, figures 7-9, 12, 13

A large Limopsis allied to dalli and other deep-water 

species from the west coast of Central America and 

southern Chile. Obliquely elongate; some specimens, 

probably distorted, are short. Sculpture consisting of 

radial pits, between some of which faint or distinct 

narrow radial grooves extend. Near the upper posterior margin the grooves are generally replaced by 

narrow faint threads. Growth lines interrupt the 

grooves. Cardinal area and hinge plate moderately 

narrow. Hinge apparently symmetrical.

Length 17.8 millimeters, height 15.4 millimeters, 

diameter (left valve) 4 millimeters (gaping paired shell, 

holotype). Length 20.5 millimeters, height 14.7 millimeters, diameter 3 millimeters (left valve, paratype). 

Length 18.4 millimeters, height 21.5 millimeters, diameter 6 millimeters (short, probably deformed left valve).

Holotype, U. S. Nat. Mus. 496077; paratype, U. S. 

Nat. Mus. 496078.

L. phrear has not been found at outcrop localities 

but has been obtained from widely distributed wells in 

the basin. Two of the specimens are short (pi. 5, 

figs. 8, 13) and have a greater diameter than elongate 

ones; and the one short specimen on which the cardinal 

area and hinge are exposed has a wider cardinal area 

and hinge plate than the one elongate specimen on which 

these features are exposed. It is improbable that two 

forms similar in most features are represented in this 

material; and inasmuch as the allied modern species are 

elongate, it is assumed that the short specimens are 

deformed. The elongate paratype is somewhat crushed. 

The radial grooves and pits are more closely spaced on 

the paratype than on other specimens of comparable 

size. In the modern species long hairs forming part of

j.45f>«9 as-
32

a thick periostracal pelage are inserted in the pits and 

grooves. The hinge is exposed on two specimens, but 

most of the teeth are broken, probably having been 

damaged during preparation.

This species is closely allied to three large deep-water 

species from the west coast of Central America and 

southern Chile "compressus" Dall 68 (=dalli Lamy; 

southern Mexico, Panama), zonalis Dall 69 (Panama); 

and jousseaumi (Mabille and Rochebrune 70) (Strait of 

Magellan), which as shown in the table under the heading "Inferred depth range of larger fossils" were dredged 

by the Albatross at depths of 122 to 2,232 fathoms. 

These three species were differentiated by Dall principally on characters of the periostracum. L. phrear 

is so far as now known smaller than these three species, 

elongate specimens are more elongate, and the radial 

grooves and pits are more widely spaced, except on the 

holotype. L. zonalis generally has a wider ligament 

area and hinge plate, and jousseaumi.h&s slightly fainter

sculpture. The fossils appear to be most closely allied 

to dalli. 

Several subdivisions have been proposed under 

Limopsis,71 based principally on characters of the inner 

margin of the shell and sculpture,72 .but there is no 

agreement as to the value of these characters. Felicia 73 

was proposed on the grounds that it has no ligament pit 

and that the muscle scars differ from those of Limopsis. 

Bernard,74 Dall,75 and Lamy,76 the last of whom examined the type material, showed that jousseaumi has 

a ligament pit. Numerous specimens dredged by the 

Albatross in the type region are similar to the figure of 

jousseaumi. They have a ligament pit, and the muscle 

scars are essentially like those of L. aurita. Nevertheless Felicia appears to be useful for a minor group of 

large deep-water western American and southern South 

American species that have a smooth inner margin, 

relatively widely spaced radial grooves and conspicuous 

pits, and a more symmetrical hinge than Limopsis s. s.

Specimens of Limopsis phrear from Repetto formation examined.

Locality Specimens Locality Specimens

Standard Oil Co. Emery No. 57, 

West Coyote field, depth 5,265 

feet. U. S. G. S. locality 13882.

Taylor Oil Co. Uharriet No. 1, near 

Culver City, depth 3,221 feet. 

U. S. G. S. locality 13887.

Pacific Western Oil Corporation 

Cone No. 16, Inglewood field, 

depth 2,926 to 2,945 feet. U. S. 

G. S. locality 13892.

Western Consolidated Oil Co. 

Smith No. 1, Inglewood field, 

depth 3,941 feet. U. S. G. S. locality 13924.

Ufiion Oil Co. Callender No. 27, 

Dominguez field, depth 4,998 feet. 

U. S. G. S. locality 13896.

Elongate left valve. 

Short right valve.

Virtually complete short 

left valve (figured).

Incomplete short left 

valve and impression of 

part of a valve.

Elongate left valve (figured paratype).

Union Oil Co. Hellman No. 19, 

Dominguez field, depth 4,292 feet. 

Collection of Union Oil Co.

Shell Oil Co. Reyes No. 43, Dominguez field, depth 5,128 feet. 

Collection of Union Oil Co.

Shell Oil Co.Reyes No. 101, Dominguez field, depth 5,245 feet. 

U. S. G. S. locality 13900.

Signal Finance Corporation Woods 

No. 1, southwestern part of sec. 

10, T. 3 S., R. 14 W., depth 5,100 

feet. Collection of Union Oil Co.

Standard Oil Co. Bolsa No. 38, 

Huntington Beach field, depth 

3,874 to 3,894 feet. U. S. G. S. 

locality 13974.

Incomplete left valve.

Incomplete paired specimen.

Elongate paired gaping 

specimen (figured holotype) .

Elongate right valve and 

impression; part of shell 

on impression.

Incomplete elongate deformed right valve.

Family PECTINIDAE 

Genus LYROPECTEN Conrad

Lyropecten cerrosensis (Gabb)

Plate 7 

Peclen cerrosensis Gabb, California Geol. Survey, Paleontology,

vol. 2, p. 32, 1866; p. 103 (list), pi. 9, figs. 55, 55a, 1869.

Cerros Island, Lower California; probably Miocene

(p. 32), post-Pliocene (p. 103). 

Watts, California State Min. Bur. Bull. 19, p. 222 (list,

"?"), 1900. Pirn Creek and vicinity; middle Neocene. 

English, California Univ., Dept. Geology, Bull., vol. 8,

p. 210 (list), 1914. Elsmere Canyon, Holser Canyon;

lower Fernando, Pliocene. . .

68 Dall, W. H., Diagnoses of new species of mollusks from the west coast of America: 

U. S. Nat. Mus. Proc., vol. 18, p. 16,1896; The Mollusca and the Brachippoda [Albatross Kept.]: Harvard College Mus. Comp. Zoology Bull., vol. 43, no. 6, p. 394, pi. 7, 

figs. 7, 8, 1908. Lamy, E., Revision des Limopsis vivants du Museum d'histoire 

naturelle de Paris: Jour. Conchyliologie, vol. 60, p. 137, footnote, 1912 (L. dalli, new 

name for L. compressus Dall, 1896, not L. compressa G. and H. Nevill, 1874). Finlay, 

H. J., Invalid molluscan names, no. 1: New Zealand Inst. Trans., vol. 61, p. 67,1930 

(L. solicola, new name for L. compressus Dall, 1895 [1896], not L. compressa G. and H. 

Nevill, 1874).

«» Dall, W. H., op. cit. (1908), pp. 393-394, pi. 7, figs. 6, 9.

'<> Rochebrune, A. T. de, and Mabille, J., Mollusques: Miss. Sci. Cap Horn, Zoologie, vol. 6, p. H116, pi. 7, fig 9.1889 (as Felicia).

Kew, U. S. Geol. Survey Bull. 753, p. 78 (list),. 1924.

Elsmere Canyon, Holser Canyon; Pico formation, lower

Pliocene. /. .« 

Stewart, Acad. Nat. Sci. Philadelphia'Special Pub. 3, p. 118,

1930. . ' ' k., 

Pecten (Lyropecten) ashleyi Arnold,. U. S.. Geol. Survey Prof.

Paper 47, pp. 122-123, pi. 47, figs,.1,.la, pi. 48, fig. i; 1906.

Cerros Island, Lower California (type locality), San Diego,

Third Street tunnel, Los Angeles; Pliocene.

71 Sassi, A., Giorn. ligustico, vol. 1, p. 476, 1827 (Cited from SherbOrn, Index animalium, sec. 2, 1801-1850, p. 3572, 1927). Type (fide Sacco; Molluschi dei terreni 

terziarii del Piemonte e.della Liguria, pt. 26, p. 39,1898), Area aurita, Brocchi, Miocene to Recent, Mediterranean. ... ...

72 See Dall, W. H., Harvard College Mus. Comp. Zoology Bull., vol. 43, p. 393,1908; 

Lamy, E., op. cit., pp. 110-112,1912. The generic names Loringella, Phrynelima, and 

Aspalima (Iredale, Tom, Mollusca from the continental shelf of eastern Australia, 

no. 2: Australian Mus. Rec., vol. 17, p. 160. 1929) and Versipella 'and Seneclidens 

(Iredale, Tom, Australian molluscan notes, no. 1: Idem, vol. 18, pp. 203-204, 1931) 

have been proposed for' Australian species.

" Rochebrune, A. T. de, and Mabille. J., op. cit., pp. H115-116, 1889. Monotype, 

Felicia jousseaumi Mabille and Rochebrune.

74 Bernard, F61ix, Recherches ontogfiniques et morphologiques sur la coquille des 

lamellibranchs: Annales sci. nat., Zoologie, 8th ser., vol. 8; p. 107, 1898.

« Dall, W. H., op. cit., pp. 393, 395, 1908.

78 Lamy, E., Mission dans 1'Antarctique dirigee par M. le Dr. Charcot; P616cypodes: Mus. nat. histoire nat. (Paris) Bull., vol. 7, p. 392,1910; Revision des Limopsis 

vivants du Museum d'histoire naturelle de Paris: Jour. Conchyliologie, vol. 60, 

p. Ill, 1312. '
MOLLUSKS 33

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 

309, p. 240, pi. 34, fig. 2 (type), 1907. Cerros Island, 

Pliocene. 

Pecten ashleyi Arnold. Arnold (part), U. S. Geol. Survey Prof.

 Paper 47, pp. 28 (list), 91 (list), 95 (list), 116 (list), 121 

(list), 1906. San Diego, Puente Hills, Third Street 

tunnel, Los Angeles; Pliocene.

Arnold, U. S. Nat. Mus. Proc... vol. 32, p. 527 (two lists), 

1907. Third Street tunnel, Los Angeles, Temescal Canyon; middle Fernando formation, lower Pliocene.

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 309, 

pp. .107, 152 (lists), 1907. Puente Hills; Fernando formation. Third Street tunnel, Los Angeles; Fernando 

formation, lower Pliocene.

English, California Univ., Dept. Geology, Bull., vol. 8, p. 

210 (list), 1914. Elsmere Canyon; lower Fernando, 

Pliocene.

Kew, U. S. Geol. Survey Bull. 753, p. 78 (list), 1924. Elsmere Canyon, between Holser Canyon and San Martinez 

Crande Canyon; Pico formation, lower Pliocene.

English, U. S. Geol. Survey Bull. 768, p. 43 (list, from 

Arnold's list), 1926. Puente Hills; Fernando group, 

Pliocene.

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43, 

p. 1058 (Arnold's list), 1932 [1933]. Third Street tunnel, 

Los Angeles; middle Pliocene.

Peclen (Plagioclenium) cerrosensis Gabb. Hertlein, California 

Acad. Sci. Proc., 4th ser., vol. 14, pp. 15-16, pi. 6, fig. 1 

(type), 1925. Cedros Island, Lower California; Pliocene 

(see p. 6).

Pecten (Lyropecten) cerrosensis Gabb. Jordan and Hertlein, 

California Acad. S6i. Proc., 4th ser., vol. 15, pp. 418, 432- 

433, pi. 32, fig. 4, 1926. Cedros Island, Lower California; 

Pliocene.

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43, 

p. 1058 (list), 1932 (1933). Third Street tunnel, Los 

Angeles; middle Pliocene (Arnold's record of P. ashleyi). 

"Peclen" cerrosensis Gabb. Woodring, California Acad. Sci. 

Proc.,,4th.ser., vol. 19, pp. 59, 62 (lists), 1930. North of 

Simi Valley, Temescal Canyon; Pliocene.

Woodring, in Hoots, U. S. Geol. Survey Prof. Paper 165, 

p. 116 (list). Potrero Canyon; upper Pliocene. Idem, 

p. 119 -(list), 1931. Temescal Canyon; San Diego formation, middle or upper Pliocene.

Pecten (Lyropecten) estrellanus (Conrad) var. cerrosensis Gabb. 

Grant and Gale, San Diego Soc. Nat. History Mem., vol. 

1, pp. 21 (discussion), 33 (discussion), 34 (discussion), 40 

(discussion), 46 (discussion), 187, pi. 8, figs, la, Ib, 2a, 2b, 

pi. 9, fig..'2, 1931. Figured specimens from Holser Canyon, Picb Canyon, and a locality between San Fernando 

Pass and Pico Canyon; middle Pliocene.

Not Pecten (Plagioclenium} cerrosensis Gabb. Arnold, U. S. 

GeoL Survey Prof. Paper 47, pp. 123-124, pi. 44, fig. 5, 

pi. 49, figs. 1, la, Ib.

A large Lyropecten sculptured with 16 or 17 ribs. 

Ribs and interspaces bearing riblets. Ears (of left valve) 

sculptured with numerous riblets.

Restored length about 125. millimeters, restored 

height about 120 millimeters, length of cardinal margin 

about 60 millimeters (figured left valve). Length about 

132 millimeters, restored height about 130 millimeters 

(mold, identification doiibtful).

An incomplete left valve (pi. 5, fig. 2), backed by a 

mold of another valve, and parts of an apparently different valve (pi. 5, fig. 1) in Hamlin's Third Street

tunnel coUection are referred to L. cerrosensis. A mold 

of a valve, which has some inner shell material, of comparable size and ribbing, and the interior of the lower 

part of a large valve from the same locality are doubtfully referred to it. A midrib is absent in the interspaces in the umbonal part of the left valve. Fragments from the Puente Hills (locality 3907, Olinda Hill, 

south of western wells of Fullerton Consolidated Oil 

Co.) also fail to show a strong midrib near the lower 

margin of the valve, but in some interspaces one riblet 

is a little stronger than others. Fragments of an exceptionally large valve from San Diego mentioned by 

Arnold 77 (locality 2474, second bench back on mesa, 

three-fourths of a mile northeast from Pacific Beach, 

near San Diego; associated with Patinopecten healeyi} 

have a riblet stronger than the others in the interspaces 

some distance from the margin of the valve, in the 

middle of the interspaces or a short distance from the 

middle. Hertlein's figure of the type of cerrosensis 

shows a riblet slightly stronger than others in interspaces on the middle of the right valve about halfway 

between the umbo and lower margin; Arnold's figures 

of the type of ashleyi apparently do not show a stronger 

riblet on either valve. The figure of a young right 

valve of P. cerrosensis from the type locality, published 

by Jordan and Hertlein, shows a relatively strong midrib in at least some of the interspaces.

Lyropecten cerrosensis was considered a variety of 

estrellanus by Grant and Gale. It was compared with 

crassicardo by Arnold and appears to be allied to crassicardo. A lot of seven imperfect specimens from the 

Estrella Valley (U. S. Nat. Mus. 13317) is regarded as 

the type lot of L. estrellanus (Conrad), 78 unless the type 

is found at the Philadelphia Academy of Natural 

Sciences. The specimen figured by Conrad is not' 

recognized, 79 and the right valve figured by Arnold 80 

is taken as the lectotype. These valves are strongly 

inflated; the lectotype and two others, on which the 

number of ribs is discernible, have 17 ribs; the interspaces are occupied by a strong midrib, which is split 

toward the margin, and the two branches may be 

flanked by a riblet. The anterior ear of a right valve 

has four relatively strong ribs. L. estrellanus has been 

recognized in the Santa Margarita sandstone of the 

type region, but the horizon of the Santa Margarita, 

generally assigned to the upper Miocene, in this region 

is not recorded. Arnold's figured right valve from the 

Santa Margarita sandstone of the Coalinga region 81

77 Arnold, Ralph, Tertiary and Quaternary Pectens of California: U. S. Qeol. 

Survey Prof. Paper 47, p. 123, 1906.

7« Conrad, T. A., Descriptions of three new genera, twenty-three new species middle Tertiary fossils from California, and one from Texas: Acad. Nat. Sci. Philadelphia 

Proc., 1856, p. 313, 1857 (as Pallium); Description of the Tertiary fossils collected 

on the survey: U. S. Pacific R. R. Expl., vol. 6, pt. 2, p. 71, pi. 3, fig. 15, 1856 (?), 

as (Pallium).

« The figured specimen was not recognized by Marcou (U. S. Nat. Mus. Proc., 

vol. 8, p. 341, 1885).

so Arnold, Ralph, op. cit. (Prof. Paper 47), pi. 20, fig. 1, 1906.

81 Arnold, Ralph, Paleontology of the Coalinga district, California: U. S. Oeol. 

Survey Bull. 396, pi. 10, fig. 3, 1909 [1910] (as Pecten).
34 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

is strongly inflated; is sculptured with 17 ribs; has a 

strong midrib that is not split toward the margin but 

in some interspaces is not stronger than riblets added 

near the margin; and has four relatively strong ribs on 

both ears. Strongly marked "resting stages", possibly 

induced by unfavorable conditions, produce humps in 

the profile. Arnold 82 figured another specimen from 

the Santa Margarita (San Pablo of Professional Paper 

47) of the Coalinga region that closely resembles the 

typical form aside from the strong "resting stages." 

Arnold's figured left valve from locality 3586, in the 

Salinas Valley,83 is not so strongly inflated and has 

15 ribs and a narrow midrib that does not split but is 

a little heavier (or of about the same strength) than 

riblets added near the margin. This is not the typical 

form of estrettanus; it is probably estrellanus terminus 

(Arnold), 84 the type of which, from an indefinite locality 

in Monterey County, is in the collections of the University of California. Arnold thought that this form 

that has fewer ribs is at a higher horizon than the 

typical form. 85 Nomland's "Pecten terminus Arnold," 

from the Chione elsmerensis zone (Jacalitos formation) 

and Turntella nova zone (lower part of Etchegoin formation or upper part of Jacalitos formation) of the 

Coalinga region, 86 is larger, relatively longer, and more 

inflated and has squarer ribs. If the interpretation of 

estrellanus terminus here offered is confirmed, the 

Jacalitos form is an unnamed species allied to estrellanus. Perhaps the Jacalitos form is the one that 

occurs in the Pliocene at Elsmere Canyon, recorded by 

Ashley 87 as Liropecten estrellanum (Conrad), by 

Arnold 88 as Pecten estrellanus (Conrad) var. catalinae 

Arnold, and by Grant and Gale 89 as Pecten (Lyropecteri) 

estrellanus (Conrad) s. s. The only specimen in the 

National Museum from Elsmere Canyon is part of a 

large flat (crushed?) valve showing wide, rather square 

ribs. The flatness probably led Arnold to identify it 

as estrellanus var. catalinae. According to the figure, 90 

the type of catalinae from Santa Catalina Island has a 

strong midrib filling the interspaces, as in estrellanus s. s. 

Material from the Pliocene at Temescal Canyon mentioned by Arnold 91 as representing catalinae is not 

recognized in the National Museum collection. This 

record is probably an error, as catalinae is not men8» Arnold, Ralph, op. cit. (Prof. Paper 47), pi. 21, figs. 1, la, Ib, 1906.

8' Idem, pi. 19, figs. 1, la.

8< Idem, p. 77, pi. 23, figs. 2, 2a [as Pecten (Lyropecten)].

" Idem, p. 76.

so Nomland, J. 0., The Etchegoin Pliocene of middle California: California Univ., 

Dept. Geology, Bull., vol. 10, pp. 212, 213, 219, table opp. p. 230, pi. 6, fig. 4,1917.

s? Ashley, Q. H., The Neocene stratigraphy of the Santa Cruz Mountains of 

California: California Acad. Sci. Proc., 2d ser., vol. 5, p. 338, 1895.

ss Arnold, Ralph, New and characteristic species of fossil mollusks from the oilbearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 32, 

p. 527, 1907.

8» Grant, U. S., IV, and Gale, H. R., op. cit., pp. 185-186, pi. 8, fig. 4,1931.

10 Arnold, Ralph, op. cit. (Prof. Paper 47), pp. 76-77, pi. 20, figs. 3, 3a, 4, 1906.

«Idem, p. 77.

tioned in Arnold's later lists from this locality. The 

strong midrib indicates that Pecten (Lyropecten) gallegosi 

Jordan and Hertlein, 92 from Cedros Island, where it is 

associated with cerrosensis, is allied to estrellanus. It 

was considered the same as cerrosensis by Grant and 

Gale. 93 Two fragments from the Puente Hills (locality 

3907, already mentioned), associated with fragments 

of cerrosensis, have more closely spaced and squarer 

ribs than cerrosensis and may represent gallegosi. The 

larger fragment, representing an area near the lower 

margin of a valve, does not have a strong midrib; the 

other, from the region near an ear, is poorly preserved 

but also does not show a strong midrib.

L. cerrosensis is larger than L. estrellanus, estrellanus 

catalinae, and estrellanus terminus but is not much 

larger than the Jacalitos form and gallegosi; it also lacks 

the strong midrib of estrellanus and its allies, those on 

the young shell figured by Jordan and Hertlein being 

weaker than in estrellanus. It is almost as large as the 

Miocene L. crassicardo (Conrad),94 which has similar 

ribs and riblets, but the ribs of crassicardo are squarer 

near the margin of large valves, and the ears are 

sculptured with fewer riblets. On some specimens of 

crassicardo a riblet in some of the interspaces is stronger 

than the others. A fragment of a large valve from 

locality 3586 in the same tray with Arnold's figured 

"estrellanus" is indistinguishable from fragments of 

crassicardo and cerrosensis. Arnold identified and 

figured a specimen, from an unknown California 

locality, in the collections of the Philadelphia Academy 

of Natural Sciences as the type of crassicardo. This 

species is widely distributed in the upper Miocene and 

is recorded from horizons assigned to the middle 

Miocene.

Lyropecten 95 is characterized by its large, heavy 

shell, approximately equal inflation of the valves and 

equal size of the ears, strong undivided radial ribs, and 

strong cardinal lamellae. At an early date Meek 9e 

pointed out the principal characters, and Verrill 97 

indicated that it should be given generic rank. Verrill

82 Jordan, E. K., and Hertlein, L. G., Contribution to the geology and paleontology 

of the Tertiary of Cedros Island and adjacent parts of Lower California: California 

Acad. Sci. Proc., 4th ser., vol. 15, pp. 434-435, pi. 29, fig. 1, 1928.

93 Grant, U. S., IV, and Gale, H. R., op. cit., p. 187.

84 Conrad, T. A., Descriptions of three new genera, twenty-three new species 

middle Tertiary fossils from California, and one from Texas: Acad. Nat. Sci. Philadelphia Proc., 1856, p. 313, 1857 (as Pallium). Arnold, Ralph, op. cit. (Prof. Paper 

47), pp. 71-73, pi. 16, figs. 1, la, pi. 17, figs, 1, la, Ib, pi. 18, figs..l, 2, 2a, 1906 [as Pecten 

(Lyropecten)]. Arnold, Ralph, Paleontology of the Coalinga district, California: 

U. S. Geol. Survey Bull. 396, pi. 12, fig. 1,1909 [1910] (as Pecten). Grant, U. S., IV, 

and Gale, H. R., op. cit., pp. 183-184, pi. 9, figs. 4, 5, 1931 (as Pecten (Lyropecten) 

magnificus Sower by variety crassicardo).

85 Conrad, T. A., Descriptions of new genera, subgenera, and species of Tertiary 

and Recent shells: Acad. Nat. Sci. Philadelphia Proc., 1862, p. 291. Subsequently 

designated type (Dall, Wagner Inst. Sci. Philadelphia Trans., vol. 3, pt. 4, pp. 695, 

701,1898), Pallium estrellanum Conrad, Miocene, California.

8« Meek, F. B., Check list of the invertebrate fossils of North America; Miocene: 

Smithsonian Misc. Coll., no. 183, p. 27,1864.

»' Verrill, A. E., A study of the family Pectinidae, with a revision of the genera and 

subgenera: Connecticut Acad. Sci. Trans., vol. 10, pp. 63-64, 1897.
MOLLUSKS 35

and also Stoliczka °8 cited Pecten nodosus (Linne1 ) ai 

the type of Lyropecten, probably following Fischer'i 

citation 90 of that species as an example. In a later 

account Conrad l included nodosus under this genus. 

P. nodosus is the type of Nodipecten Dall,2 which has 

hollow nodes on the ribs and is regarded as a subgenu 

of Lyropecten that also appeared in the Miocene, 

nodosus itself being identified in the Miocene of the 

West Indies. Species of Lyropecten that have humps 

on the shell are not properly assignable to Nodipecten. 

Lyropecten appears on the Pacific coast in the lower 

Miocene (Vaqueros formation), and the large shells of 

this genus are used by field geologists as a readily 

recognized aid in distinguishing the late Tertiary from 

the early Tertiary. There are large Pectens in the late 

Eocene and Oligocene of the Pacific coast (ynezianus 

Arnold, porterensis Weaver), but they belong to an 

endemic genus, Vertipecten,3 which became extinct in 

the Miocene and is not directly related to Lyropecten, 

as pointed out by Grant and Gale. On the Atlantic 

coast Lyropecten appears in the Oak Grove sand of 

Florida and the Calvert formation of the Chesapeake 

embayment. These formations are now considered of 

about the same age and are assigned to the middle 

Miocene,4 as that term is used in a relative sense. 

Lyropecten proper is unknown in the Tampa limestone 

(basal Miocene) of Florida but may occur in beds 

correlated with the Chipola formation of Florida (lower 

Miocene).5 Facies control may affect this distribution, 

for Lyropecten is not known in the Shoal River formation, which is younger than the Chipola formation and 

Oak Grove sand. In the Miocene of the Atlantic and 

Gulf coasts Lyropecten is associated with faunas of coolwater aspect. The Pacific coast Lyropecten has been 

considered a migrant from the West Indies and Central 

America,6 or from the Atlantic coast through Central 

America,7 but Lyropecten proper has not certainly been 

recognized in the West Indian and .Central American 

Miocene. Nodipecten, however, is widely distributed 

in the Miocene of that region. Young valves from the 

type locality of Pecten (Lyropecten) arnoldi Aguerrevere,8

88 Stoliczkn, F., Cretaceous fauna of southern India, vol. 3, p. 425, 1871 (as Liropectcn).

" Fischor, P., Manuol do conchyliologie, p. 944, 1886 (as Liropectcri).

' Conrad, T. A., Paloontological miscellanies: Am. Jour. Conchology, vol. 3, p. 6, 

1867.

»Dall, W. H., Wagner Inst. Sci. Philadelphia Trans., vol. 3, pt. 4, p. 695, 1898.

> Grant, U. S., IV, and Gale, H. R., op. cit., p. 188. Originally designated type, 

Pecten netmdanus Conrad, Miocene, California. Grant and Gale's designation of a 

specimen of uncertain provenance as the neotype of nevadanus (p. 190) is to be ignored.

4 Mansfield, W. C., Stratigraphic significance of Miocene, Pliocene, and Pleistocene 

Pcctinldaoln the southeastern United States: Jour. Paleontology, vol. 10, p. 173,1936

4 Gardner, J. A.. The molluscan fauna of the Alum Bluff group of Florida: U. S. 

Cool. Survey Prof. Papor 142-A, p. 46,1926 (Chlamys (Lyropecten) acanikos Gardner).

«Smith, J. P., Climatic relations of the Tertiary and Quaternary faunas of the 

California region: California Acad. Sol. Proc., 4th ser., vol. 9, p. 161,1919.

' Grant, U. S., IV, and Gale, H. R., op. cit., p. 176.

8 Aguorrovore, P. I., Description of a new pecten from Venezuela, S. A.: Southern 

California Acad. Sol. Bull., vol. 24, pp. 51-53, pi. 5,1925.

a Pliocene (?) species from Venezuela, indicate that it 

is a Nodipecten, probably an exceptionally large form of 

nodosus. In the Peruvian Miocene Lyropecten is 

recognized by Olsson 9 in the Tumbez formation, which 

is assigned to the upper Miocene. At the present time 

the predecessors of Lyropecten and its route of migration 

between the two coasts of America are unknown.

Similar large Pectens with strong undivided ribs and 

heavy cardinal lamellae, assigned to Gigantopecten, 10 

are found in the European Miocene and Pliocene. 

Cossmann and Peyrot claimed that Gigantopecten lacks 

a byssal sinus, but illustrations support Sacco's and 

Philippi's statement 11 that young valves have a shallow 

sinus that disappears, or virtually disappears, on 

adults. Lyropecten and Gigantopecten apparently are 

closely related. American species that have a few 

wide ribs (jeffersonius Say and magnolia Conrad) 

appear to be very similar to latissima. Gigantopecten 

was recognized by Sacco in the Oligocene (Tongrian).

Genus HYALOPECTEN Verrill

Subgenus DELECTOPECTEN Stewart

Hyalopecten (Delectopecten) aff.'H. randolphi (Dall)

Plate 6, figures 5-7, 11

Pecten (Pseudamusiuni) pedroanus (Trask) Arnold (part), U. SGeol. Survey Prof. Paper 47, pp. 90-91, pi. 28, figs. 4, 5,

1906. Figured specimens from Third Street tunnel, Los

Angeles; Pliocene, probably lower. 

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull.

309, p. 244, pi. 36, figs. 5, 6, 1907. Third Street tunnel,

Los Angeles; lower Pliocene. (Same illustrations as in

Prof. Paper .47, but considerably reduced.) 

Pecten pedroanus (Trask) Arnold, U. S. Geol. Survey Prof. Paper

47, pp. 116 (list), 123 (list), 1906. Third Street tunnel,

Los Angeles; Pliocene. 

Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 527 (list), 1907.

Third Street tunnel, Los Angeles; middle Fernando

formation, lower Pliocene. 

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull.

309, p. 152 (list), 1907. Third Street tunnel, Los Angeles;

Fernando formation, lower Pliocene. 

?Arnold, idem, p. 153 (list). Normal School and Clark

estate, Los Angeles; Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol.

43, p. 1058 (Arnold's list), 1932 (1933). Third Street

tunnel, Los Angeles; middle Pliocene.

8 Olsson, A. A., Contributions to the Tertiary paleontology of northern Peru, 

pt. 5, The Peruvian Miocene: Bull. Am. Paleontology, vol. 19, no. 68, p. 83, pi. 6, 

figs. 1, 4, 1932 (Pecten (Lyropecten) hoj>k\nsi, renamed Pecten tucilla on p. 226).

1° Roverto, G., Rectifications de nomenclature: Rev. crit. pa!6ozoologie, year 3, 

p. 90,1899; new name for Macrochlamys S.acco, 1897, not Benson, 1832; type (see under 

Macrochlamys), Ostrea latissima Brbcchi, Miocene, Italy. Macrochlamys Sacco, 

Molluschi dei terreni terziarii del Piemonte e della Liguria, pt. 24, p. 32, 1897 (as 

subgenus of Chlamys); originally designated type, M. latissima (Brocchi). Grandipecten Cossmann and Peyrot, Conchologie n6og6nique de I'Aquitaine, vol. 2, pt. 2, 

p. 273, 1914; new name for Macrochlamys Sacco, 1897, not Benson, 1832 (as section of 

Amussiopecten, subgenus of Pecten). Cossmann overlooked Roverto's name issued 

n his own publication.

11 Philippi, E., Beitrage zur Morphplogie und Phylogenie der Lamellibranchier, 

II, Zur Stammesgeschichte der Pectinidae: Deutsche geol. Gesell. Zeitscbr., vol. 52, 

p. 105,1900.
36 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Pecien (Pseudamussiu-m) pedroanus (Trask) Grant and Gale

(part), San Diego Soc. Nat. Hist. Mem., vol. 1, pp. 236-

237, 1931. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol.

43, p. 1058 (list), 1932 (1933). Third Street tunnel, Los

Angeles; middle Pliocene (Arnold's record). 

IPecien pedroanus (Trask) Cooper, in Watts, California State

Min. Bur., Bull. 11, p. 4 (mentioned), 1897. Clark estate

[between Los Angeles River and Arroyo Seco, see fig. 30];

Miocene. Idem, p. 80 (list). Normal School, Clark

estate, Los Angeles. 

Not Plagiostoma pedroana Trask, California Acad. Sci. Proc.,

vol. 1, p. 86, figs. 1, la, 1856 (pedrona in text). San

Pedro; Cretaceous [Miocene].

A large Delectopecten allied to randolphi. Concentric, 

undulations strong on some specimens; moderately 

strong or weak on others. Radial sculpture absent 

except on right anterior ear, the upper part of which is 

sculptured with 5 or 6 radial ribs. Growth lines conspicuous on right anterior ear, forming low scales on 

the radial ribs. Entire shell bearing microscopic, 

somewhat pustular radial threads that bend upward 

near anterior and posterior ends of shell (camptonectes sculpture).

Length 25 millimeters, height 22.8 millimeters (right 

valve figured by Arnold). Length 32.5 millimeters, 

height 30.6 millimeters (distorted left valve figured by 

Arnold). Length 34.5 millimeters, height 33.5 millimeters (left valve, largest in core material; from a 

horizon assigned to Pico formation).

Exteriors generally have only part of the inner shell 

preserved. The camptonectes sculpture is visible on 

small patches of shell, on some impressions (pi. 6, fig. 11), 

and shows" through the thin shell on some interiors.

The fossils from the Los Angeles Basin identified as 

H. af¥. H. randolphi represent horizons ranging from 

upper Miocene to upper Pliocene. Large specimens 

are somewhat larger than the largest shells of randolphi. 

The concentric undulations on upper Miocene and 

Repetto specimens (pi. 6, fig. 7) are stronger than on 

most specimens of randolphi. The undulations are 

exceptionally strong on Third Street tunnel fossils, 

including those figured by Arnold. Perhaps these 

strongly undulated fossils .are to be regarded as a 

variety of pedroanus that lacks radial ribs except on

the right anterior ear. Fossils from the Pico formation 

have moderately strong to weak undulations, and 

specimens that have undulations of varying strength 

occur together (pi. 6, figs. 5, 6). Those that have weak 

undulations appear to be indistinguishable from 

randolphi.

The Third Street tunnel is the only outcrop locality 

for this Delectopecten in the collections at hand. The 

specimens figured by Arnold and others in the lot from 

which they were selected have the locality number 3428 

(Broadway tunnel, Los Angeles), which appears to be 

an error for 3426, as the label reads Third Street tunnel. 

Additional specimens are under a Third Street tunnel 

number (3432). Watts and later Arnold recorded 

pedroanus from other localities in Los Angeles the 

Clark estate and the Normal School. According to 

Watts' map, the Clark estate was in a region where 

strata now assigned to the Miocene crop out. The 

Normal School was on the site of the present Los 

Angeles Public Library, which is underlain by the 

Pico formation. Arnold also recorded pedroanus from 

the Pliocene of the Puente Hills. 13 The only specimen 

.from the Puente Hills now in the collections of the 

National Museum that may represent Delectopecten is 

a valve which lacks shell material and in which the ears 

are not exposed. It has weak undulations, is 16 millimeters long, and may represent a form of peckhami. 

The matrix is dense diatom-bearing limestone, possibly 

from the Miocene Puente formation. Limestone of 

coarser grain under the same locality number (3909, 

face of ridge north of Brea Canyon, opposite wells of 

Brea Canyon Oil Co.) contains molds and impressions 

of Pliocene fossils. McLaughlin and Waring's figure 

:of a pecten, identified as "pedroanus Arnold", from the 

Miocene near Eastlake [now Lincoln] Park, Los 

Angeles,13 shows the posterior ear set off from the main 

part of the shell and radial lines 011 the main part of 

the shell.

; Delectopecten is represented on the Pacific coast from 

the Eocene to the Recent.. The following names have 

been proposed:

' 2 Arnold, Ralph, op. cit. (Prof. Paper 47), p. 91.

13 McLaughlin, R. P., and Waring, 0. A., Petroleum industry of California: 

California State Min. Bur. Bull. 69, map folio, pi. 1, fig. 35, 1914.
MOLLUSKS

Names proposed for Tertiary and Recent forms of Delectopecten from Pacific coast

37

Name Type locality Characters Remarks

Plagiostoma pcdroana 

Trask.1

Plagiosloma annulalus 

Trask. 2

Plagiostoma truncata 

Trask.8

Pecton peckhami Gabb 4 ___

Pecten (Pseudamusium) 

vancouverensis W h i t - 

eaves.5

Pecten randolphi Dall °.__

Pcctcn (Pseudamusiuni) 

randolphi var. tillamookensis Arnold.7

Pcctcn (Pscudamusium) 

polyloptus Dall.8

Pecten (Pseudamusium). 

arces Dall.8

San Pedro [east coast of 

Palos Verdes Hills], Calif. 

Cretaceous [Miocene].

.do.

.do.

Ojai ranch, Santa Barbara 

[now Ventura] County, 

Calif. Bituminous shale 

of upper Miocene [Monterey shale of some geologists and Modelo formation of others].

Forward Inlet, Quatsino 

Sound, Vancouver Island; 

depth 10 to 20 fathoms.

Off Destruction Island, 

Wash.; depth 516 fathoms.

Off Tillamook Bay, Oreg.; 

depth 786 fathoms.

Off Hood Island, Galapagos; 

depth 300 fathoms.

Santa Barbara Channel, 

Calif., off Santa Cruz 

Island; depth 534 fathoms.

Large; length about 35 mm [apparently 

exaggerated by deformation]. Concentric undulations strong. Right 

anterior ear sculptured with about 13 

radial ribs. (Fide Trask.)

Large; length about 32 mm [apparently 

exaggerated by deformation]. Concentric undulations strong. Left anterior ear sculptured with about 12 

radial ribs. (Fide Trask.)

Large; length about 28 mm [apparently 

slightly exaggerated by deformation]. 

Concentric undulations strong. 

(Fide Trask.)

Small; length of 3 specimens in lectotype lot 12 to 14.8 mm. Concentric 

undulations weak. Lectotype sculptured with weak, relatively widely 

spaced radial ribs on main part of 

shell. Right anterior ear sculptured 

with a few radial ribs (6 or 7; fide 

Arnold).

Small; length 8.5 to 10 mm. Concentric undulations weak or absent. 

Main part of shell sculptured with 

weak to strong radial ribs; absent on 

some specimens. Right anterior ear 

sculptured with 5 to 7 radial ribs.

Large; length 28 to 30.8 mm. Concentric undulations moderately strong or 

weak. Right anterior ear sculptured 

with 5 to 8 radial ribs.

Large; length 29 to 32.5 mm. Concentric undulations moderately strong or 

weak. Type sculptured with weak 

radial ribs on main part of shell. In 

other specimens this radial sculpture 

varies from a few faint ribs to strong 

ribs covering entire shell. Some left 

valves that lack radial sculpture are 

paired with faintly sculptured right 

valves. Right anterior ear sculptured with 5 to 8 radial ribs.

Small; length 9.6 to 10 mm. Concentric undulations weak or absent. 

Main part of shell sculptured with 

weak radial ribs, mainly in form of 

vaulted scales. Right anterior ear 

sculptured with 4 or 5 radial ribs.

Moderately large; length 19.5 to 23 mm 

(type lot). Concentric undulations 

moderately strong or weak. Main 

part of shell sculptured with strong 

radial ribs. Right anterior ear 

sculptured with 5 to 7 radial ribs.

Large number of ribs on right 

anterior ear needs confirmation.

Considered same as pedroanus. 

Radial ribs on left anterior 

ear suggest that well-preserved specimens may show 

radial ribs on main part of 

shell.

Considered same as pedroanus.

On -many specimens that appear to represent peckhami 

radial ribs are not discernible, except on right anterior 

ear. Forms resembling peckhami have been recorded 

fr.om horizons ranging from 

Eocene to Miocene:

Radial sculpture very variable 

in lots assigned to this form. 

Apparently ranges from 

southern Alaska to San 

Diego in shallow to moderately deep water (12 to 200 

fathoms).

Apparently ranges from Bering 

Sea to Cape Blanco, Oreg., 

in deep water (225 to 1,064 

fathoms).

Considered a sculptured variety of randolphi, as- described by Arnold. Radial 

sculpture very variable in 

suites of shells assigned to 

this variety. Apparently 

ranges from Bering Sea to 

San Diego, generally in deep 

water (30 to 1,084 fathoms).

Represented in two lots from 

depths of 300 and 392 

fathoms near Galapagos. 

Apparently closely allied 

to H. gelatinosus (Mabille 

and Rochebrune), a larger 

form from southern South 

America.

Considered a synonym of tillamookensis; strongly sculptured form.

' Trask, J. B., Description of throo now species of the genus Plagiostoma from the Cretaceous rocks of Los Angeles: California Acad. Sci. Proc., vol. 1, p. 86, flgs. I, la, 

.1850 (yedrona in text). 

1 Idem, p. 86, flg. 2.

4 Gabb, W. M., California Ocol. Survey, Paleontology, vol. 2, pp. 59-60, pi. 16, flgs. 19,19a, 1869. Stewart, R. B., Gabb's Cretaceous and Tertiary typo lamellibranchs: 

Acad. Nat. Scl., Philadelphia Special Pub. 3, pp. 119-120, pi. 13, fig. 4,1930.

4 Whltoavos, J. F., Notes on some marine Invertebrata from the coast of British Columbia: Ottawa Naturalist, vol. 7, no. 9, pp. 133-134, pi. 1, figs. 1, la, 1893. Illustrations reproduced by Arnold, Ralph, op. cit. (Prof. Paper 47), p. 140, pi. 52, figs.. 3,- 3a, 1906.

« Dall, AV. II'., Now west American shells: Nautilus, vol. 11, p. 86, 1897; Illustrations and descriptions of new, unfigured, or imperfectly known shells, chiefly American, 

lu the U. S. National Museum: U. S. Nat. Mus. Proc., vol. 24, p. 559, pi. 40, fig. 2,1902. Arnold, Ralph, Tertiary and Quaternary pectens of California: U. S. Geol. Survey 

Prof. Paper 47, pp. 138-139, pi. 48, figs. 2, 2a, 1906.

' Arnold, Ralph, op. clt. (Prof. Paper 47), p. 139, pi. 48, figs. 3, 3a, 1906.

8 Dall, W. H., The Mollusca and the Brachiopoda [Albatross Rept.J: Harvard College Mus. Comp. Zoology Bull., vol. 43;-p. 403, pi. 10, fig. 9,1908.

0 Dall W H., Diagnoses of new shells from the Pacific Ocean: U.S.Nat. Mus. Proc., vol.45, pp. 592-593,1913; Illustrations of unflgured types of shells in the collection of 

the U. S. National Museum: U. S. Nat. Mus. Proc., vol. 66, p. 24, pi. 27, flg. 4,1925.
38 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Names proposed for Tertiary and Recent forms of Delectopecten from Pacific coast Continued

Name Type locality Characters Remarks

Pecten (Pseudamusium) 

alternilineatus Clark. 10

Pecten (Pseudamusium) 

vancouverensis sanjuanen- 

. sis Clark and Arnold. 11

Pecten (Pseudamusium) 

vancouverensis fernandoensis Hertlein. 12

Peclen (Pseudamusium) 

lillisi Hertlein.13

Peclen (Delectopecten) zacae 

Hertlein.14

Presumably a locality near 

Walnut Creek, Contra 

Costa County, Calif, (see 

Clark, table opp. p. 80). 

San Ramon sandstone, 

assigned to Oligocene.

Vancouver Island, British 

Columbia. Sooke formation, assigned to Oligocene.

Ventura River, % mile 

south of Taylor well no. 

1 and \}{ miles north of 

Ventura, Calif. Fernando, Pliocene [upper 

Pliocene].

Crow Creek road, Stanislaus County, Calif. 

Kreyenhagen shale, upper 

Eocene or lower Oligocene [apparently from 

part of Kreyenhagen 

shale now assigned to 

Eocene].

Gulf of Panama; depth 322 

fathoms.

Small; length 5 to 5.5 mm. [Concentric undulations apparently weak or 

absent.] Main part of shell sculptured with radial ribs. Right anterior ear sculptured with about 5 

radial ribs. (Fide Clark.)

Small; length 7 mm. Concentric undulations moderately strong. Main 

part of shell sculptured with radial 

ribs. (Fide Clark and Arnold.)

Of medium size to moderately large; 

length 12.5 to 22.7 mm. Concentric 

undulations moderately strong to 

weak; main part of shell sculptured 

with radial ribs of varying strength. 

Right anterior ear sculptured with 

5 to 7 radial ribs.

Small; length 9 to 15.6 mm. Concentric undulations weak or moderately 

strong. Main part of shell sculptured 

with a few or many radial ribs, especially on right valves. Right anterior 

ear sculptured with 4 to. 8 radial ribs.

Moderately large; length 19 to 22 mm. 

Concentric undulations weak. Main 

part of shell sculptured with a few or 

many weak radial ribs. Right 

anterior ear sculptured with 4 to 6 

radial ribs.

Apparently allied to vancouverensis.

Apparently allied to vancouverensis.

Apparently closely allied to tillamookensis. Pliocene specimens from Los Angeles 

Basin are smaller than tillamookensis, and some have 

stronger concentric undulations.

Relations to peckhami, to which 

this form was formerly assigned, not determined. 

Some specimens have 

stronger concentric undulations than peckhami.

Specimens in collection of 

U. S. National Museum 

more obliquely elongate 

than those of other recent 

species of comparable size.

10 Clark, B. L., The San Lorenzo series of middle California: California Univ., Dept. Geology, Bull., vol. 11, pp. 132-133, pi. 13, figs. 14, 15, 1918.

11 Clark, B.L., and Arnold, Ralph, Fauna of the Sooke formation, Vancouver Island: Idem, vol. 14, pp. 140-141, pi. 16, figs. 5, 6,1923.

i" Hertlein, L. G., New species of marine fossil Mollusca from western North America: Southern California Acad. Sci. Bull., vol. 24, p. 43, pi. 4, flgs. 6, 7,1925. 

i 3 Hertlein, L. G., New oysters and a new pecten from the Tertiary of southern California: Idem, vol. 33, pp. 5-6, pi. 1, fig. 1; pi. 2, flgs. 2, 3,1934.

 u Hertlein, L.G., The Recent Pectinidae [Templeton Crocker Expedition Rept.]: California Acad. Sci. Proc.. vol.21, pp. 321-322, pi. 18, flgs. 3-6, 9, 10,1935. (New name 

for Pecten (Psendamusium) panamensis Dall, Harvard College Mus. Comp. Zoology Bull., vol. 43, p. 404, pi. 6, flgs. 8,10,1908; not Pecten panamensis Dall, 1898.)

These little pectens apparently do not have many 

characters to serve as a basis for differentiation. 

Those that have been adequately described have the 

same kind of camptonectes sculpture and a few (4 to 

8, generally 5 to 7) radial ribs on the right anterior ear, 

with the apparent exception of pedroanus. According 

to Trask's description and figure, pedroanus has 13 

radial ribs on the right anterior ear. Nevertheless, as 

has recently been suggested,14 it appears desirable to 

attempt some differentiation in this large group embracing small to relatively large forms, weakly to strongly 

sculptured forms, and forms having weak to strong 

concentric undulations.

The presence or absence of radial ribs on parts of the 

shell other than the right anterior ear appears to be of 

doubtful value for specific differentiation. Large 

suites of specimens agreeing in other characters show 

gradations from strong sculpture to none. This 

gradation is well shown in the modern forms (vancouverensis, randolphi, and tillamookensis), in the 

Oligocene and Miocene forms assigned to peckhami, 

and in the form from the Eocene part of the Kreyenhagen shale formerly assigned to peckhami and recently 

named lillisi. The radial ribs vary from strong 

beaded or scaly ribs covering the entire shell to weak

n Slodkewitsch, W. S., Stratigraphy and fauna of the Tertiary deposits of the 

western coast of Kamchatka, pt. 1: Geol. Oil Inst. Trans., ser- A, fasc. 79, pp. 171-173 

(English summary), 1936-

ribs confined to a small part or parts of the shell. 

Many right valves that elsewhere lack radial ribs, 

aside from those on the anterior ear, have a few at 

the anterior margin of the shell. Some left valves that 

are paired with weakly sculptured right valves lack 

radial ribs entirely or they are restricted to the anterior 

ear. The presence or absence of radial ribs is considered 

of varietal rank, and perhaps this rank is open to 

question.

The size of the shell and the strength of the concentric 

undulations appear to offer grounds for specific differentiation. The possible value of these characters, however, is undetermined in many of the forms. The outline of the shell may be a characteristic feature in some 

Recent forms, but many fossil specimens are deformed.

The three forms named by Trask have been regarded 

since Gabb's time as specimens of the same species 

representing varying degrees of deformation. According to a communication from L. G. Hertlein, Trask's 

material is not in the collections of the California 

Academy of Sciences. Trask's descriptions and illustrations evidently represent a large species that has 

strong concentric undulations. He described and 

showed "about 13" radial ribs on the right anterior ear 

of pedroanus and "about 12" on the left anterior ear of 

annulatus. The sculpture on the left anterior ear 

suggests that well-preserved specimens of this species 

may show radial ribs on the main part of the shell.
MOLLUSKS 39

The large number of ribs on the right anterior ear 

needs confirmation. Other radially sculptured forms 

have 10 to 13 ribs on the left anterior ear, but only 4 to 

8 on the right anterior ear, the lower part of 'which 

lacks radial ribs. Trask's specimens were examined by 

Gabb,15 who stated that they were casts and that the 

sculpture is unknown. Trask's specimens evidently 

came from the lower part of the Valmonte diatomite 

member of the Monterey shale or the upper part of the 

underlying Altamira shale member exposed near the 

breakwater at Cabrillo Beach, for this is the only 

locality on the east coast of the Palos Verdes Hills 

where the beds dip as steeply as recorded by Trask 

("about 50°")- Through the kindness of Hertlein a 

collection of pectens from the Valmonte diatomite 

about 220 yards northwest from the breakwater is 

available (California Acad. Sci. no. 1894). These 

specimens have weak or moderately strong concentric 

undulations, and the largest (length 15 millimeters, 

height 14.7 millimeters) is about half as large as 

Trask's. Impressions of two incomplete right valves 

show a few radial ribs near the anterior margin of the 

shell; impressions of two left valves show weak radial 

ribs on the anterior ear, and one of these shows indistinct traces of radial ribs at the margin of the shell near 

the anterior ear. This material appears to be similar 

to peckhami. No trace of radial ribs on the left 

anterior ear or on the main part of the shell can be 

seen on the specimens from the Valmonte diatomite 

collected a few miles from the type locality of pedroanus 

and recently cited as that species 10 (locality 13837). 

They have a maximum length of 15 to 16 millimeters, 

weak concentric undulations, and 4 to 7 ribs on the right 

anterior ear and apparently represent a form oi peckhami.

A large Delectopecten (length 30 to 36 millimeters) from 

the Monterey shale in the Temblor Range at locality 

3881, 4 miles southwest of McKittrick, was identified 

by Arnold 17 as pedroanus. It has moderately strong 

concentric undulations. An impression of a left valve 

shows numerous fine radial ribs. The number of ribs 

on the right anterior ear is undeterminable. Incomplete 

impressions of a large Delectopecten (length 25+ millimeters) are represented in a collection from the Monterey shale at locality 8136, in Las Virgenes Canyon, 

on the south slope of the Simi Hills, in southeastern 

Ventura County. These impressions show numerous 

fine radial ribs. The right anterior ear is not preserved. 

The concentric undulations are weaker than in Trask's 

illustrations and in most of the impressions from 

locality 3881.

Cabb failed to compare peckhami with pedroanus. 

A squeeze of the lectotype of peckhami is available

> Gabb, W. M., California Cool. Survey, Paleontology, vol. 2, p. 60,1869.

« Woodring, W. P., in Woodring, W. P., Bramlette, M. N., and Kleinpell, R. M., 

Miocene stratigraphy and paleontology of Palos Verdes Hills, California: Am. Assoc. 

Petroleum Geologists Bull., vol. 20, p. 146,1936.

» Arnold, Ralph, op. cit. (Prof. Paper 47), p. 91,1906.

through the courtesy of W. E. Schevill, of the Museum 

of Comparative Zoology. It is a left valve that has a 

length of about 12 millimeters, weak concentric undulations, and weak, relatively widely spaced radial ribs, 

which are absent in most of the area extending downward from the umbo. These ribs are not well shown 

on the photograph of the lectotype, the radial lines of 

which appear to have been added by retouching. The 

other two specimens in the lectotype lot also are 

available through the kindness of Schevill. One a 

left valve exposed in interior view has a length of 

13 millimeters; the other a right valve that lacks the 

shell aside from small patches of inner layers has a 

length of 14.8 millimeters. Both specimens have weak 

concentric undulations, and neither shows radial ribs, 

with the exception of traces on the right anterior ear.

H. peckhami seems to be a small species that has weak 

concentric undulations and weak, relatively widely 

spaced radial ribs. In many specimens the ribs are 

apparently absent. They are absent on the specimens 

from the Monterey group of the San Francisco Bay 

region figured by Arnold. 18 On some specimens the 

apparent absence of ribs may be a matter of preservation, as the shell itself is generally not preserved, and 

preservation in the form of impressions is generally 

needed to show such weak ribs. H. peckhami is recorded from the Monterey shale and from other formations ranging in age from Eocene to Miocene.

A moderately large Delectopecten (length 20 millimeters) that has weak or moderately strong undulations 

is abundant in collections from the Miocene of Astoria, 

Oreg. (localities 2263, 5314, 5315, 5317, 5318, 5319, 

5322, 5332, 5379), where peckhami has been recorded. 19 

Impressions of a right valve from locality 5315 (loose 

concretion on river bank, lower part of Astoria) and of 

another right valve from locality 5332 (bridge on Youngs 

River 2 miles from Astoria on road to Portland, NW % 

sec. 21, T. 8 N., R. 9 W.) show a few radial ribs at the 

anterior end of the valve.

A small strongly undulated Delectopecten (length 11.5 

millimeters) is represented in the Whepley shale (of 

drillers), assigned to the lower Miocene, of the subsurface section in the Kettleman Hills, on the west side 

of the San Joaquin Valley. The specimens available 

(Petroleum Securities Felix No. 3, depth 8,495 to 9,516 

feet; Kettleman North Dome Association No. 61-2-P, 

depth 8,312 to 8,328 feet) retain some shell material 

replaced by pyrite showing the camptonectes sculpture. 

Some show obscure indications of radial ribs, but this 

may be a matter of preservation.

A right valve (length 18 millimeters) that lacks shell 

material and shows radial ribs only on the anterior ear 

was collected at the south end of the San Joaquin

» Idem, pp. 56-57, pi. 3, fig. 8.

" Howe, H. V., Astoria; mid-Tertic type of Pacific coast: Pan-Am. Geologist, vol. 

45, pp. 298, 304,1926.
40 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Valley in an area mapped as underlain by the Vaqueros 

formation 20 (locality 13315, canyon draining eastward into Santiago Creek about 2 miles below San Andreas rift).

The material from Weaver's Blakeley formation of 

Washington (Oligocene) and strata of equivalent age on 

the south shore of the Strait of Juan de Fuca cited by 

Arnold 21 as peckhami is poorly preserved. An impression of a left valve from locality 4112a, on Bainbridge 

Island, has radial ribs; and impressions of two right 

valves from locality 4114, near Gettysburg, have a few 

radial ribs at the anterior end of the valve.

Radial ribs are not discernible on imperfect specimens of a small form (length 9 millimeters) from the. 

Oligocene of Columbia and Clatsop Counties, Oreg. 

(localities 2712, 5382, 5387).

The Delectopecten from the part of the Kreyenhagen 

shale now assigned to the Eocene was identified by 

Arnold 22 as peckhami and has recently been named 

lillisi by Hertlein. This form is represented in collections at the National Museum from localities extending 

from the north limb of the Coalinga anticline northward to the type region near Crow Creek, in Stanislaus County (localities 205, 4616, 5745, 5747, 5752, 

5760, 5762, 5787). A few right valves have ribs over 

the entire valve; others have ribs on the greater part 

of the anterior half of the valve; and on many, as on 

the one from which the squeeze figured by Arnold .was

prepared, only one or two ribs, or rows of knobs, are 

discernible at the anterior margin. Ribs were observed 

on only one left valve. This form appears to resemble 

peckhami closely; some specimens have stronger concentric undulations than peckhami. The Delectopecten 

from the Eocene part of the Kreyenhagen shale is 

associated with Propeamussium interradiatum (Gabb) 

at localities 4616 (north limb of Coalinga anticline) 

and 205 (Big Panoche Creek).

A strongly undulated right valve (length 12.5 millimeters) that lacks radial ribs is in a collection from the 

Oligocene part of the Kreyenhagen AtwilPs "Tumey 

formation" ^at locality 5756, on Arroyo Ciervo. 23

Pecten vanwinkleae,2* from the Oligocene of Washington, was described as having the right posterior ear 

differentiated from the main part of the shell, and the 

illustration shows this feature in a form that otherwise 

appears to resemble forms of peckhami.

Delectopecten,25 proposed as a subgenus of Palliolum, 

may not be closely allied to Hyalopecten,26 a deep-water 

North Atlantic genus that has a notched posterior ear, 

weaker ctenolium, concentric undulations, fine radial 

sculpture, and no camptonectes sculpture. It appears, 

however, to be more closely related to Hyalopecten, with 

which Stewart compared it, than to Palliolum,27 which 

has a heavier shell, differentiated posterior ear, and 

camptonectes sculpture of minute pustules.

Specimens of Hyalopecten aff. H. randolphi from Repetto formation examined

Locality Specimens Locality Specimens

Third Street tunnel, Los 

Angeles; Homer Hamlin. 

U. S. G. S. locality 3426. 

Specimens figured by Arnold 

and others have the locality 

number 3428 (Broadway 

tunnel, Los Angeles), which 

apparently is an error for 

3426.

Third Street tunnel, Los 

Angeles; Homer Hamlin. 

U. S. G. S. locality 3432.

7 right and 5 left valves of 

various size, 3 of which were 

figured by Arnold. Undulations strong.

Standard Oil Co. Baldwin No. 

41, Montebello field, depth 

3,600 feet. U. S. G. S. local-

: ity 13907.

Union Oil Co. Bell No. 43, 

Santa Fe Springs field, depth 

5,518 feet. Collection of 

Union Oil Co.

Incomplete large valve and 

impression (figured); part of 

left valve and impression. 

Undulations strong.

Parts of: small right (?) valve 

and impression. Undulations strong.

Right and 2 left valves, 

dulations strong.

Un20 Pack, R. W., The Sunset-Midway oilfield, California, pt. 1: U. S. Geol. Survey 

Prof. Paper 116, pi. 2, 1920.

21 Arnold, Ralph, op, cit. (Prof. Paper 47), p. 57,1906.

21 Arnold, Ralph, Paleontology of the Coalinga district, California: U. S. Geol. 

Survey Bull. 396, p. 13, pi. 3, figs. 2, 2a, 1909 [1910]. .

23 For records of a peckhami-like form in this part of the Kreyenhagen see Anderson, 

F. M., A stratigraphic study in the Mount Diablo Range of California: California 

Acad. Sci. Proc., 3d ser., vol. 2, p. 173,1905; A further stratigraphic study in the Mount 

Diablo Range of California: Idem, 4th ser., vol. 3, p. 16, 1908. Woodring, W. P., in 

Condit, D. D., Age of the Kreyenhagen shale in the Cantua Creek-Panoche district, 

California: Jour. Paleontology, vol. 4, p. 261,1930. Atwill, E. R., Oligocene Tumey' 

formation of California: Am. Assoc. Petroleum Geologists Bull., vol. 19, p. 1200, 

1935.

2< Clark, B. L., Pelecypoda from the marine Oligocene of western North America: 

California Univ., Dept. Geol. Sci., Bull., vol. 15, pp. 82-83,.pl. 15, fig. 2,1925.

25 Stewart, R. B., Gabb's California Cretaceous and Tertiary type lamellibranchs: 

Acad. Nat. Sci. Philadelphia Special Pub. 3, p. 118,1930. Originally designated type, 

Pecten (Pseudamusium) Vancouver ensis Whiteaves.

26 Verrill, A.- E., A study of the family Pectinidae, with a^revision of the genera and 

subgenera: Connecticut Acad. Sci. Trans., vol. 10, p. 71,1897. Originally designated 

type, Hyalopecten undatus Verrill, Recent, off Maryland (cf. Pecten ftagilis Jeffreys, 

1876, North Atlantic).

' « Monterosato, Marchese di, Nomenclature generica e specifica di alcune conchiglie 

imediterranee, p. 5, 1884. Subsequently designated type (Crosse, Jour. Con? 

chyliologie, vol. 33, p. 140, 1885), Pecten incomparabilis Risso, Recent, Mediterranean (frequently cited as P. testae Bivona).
MOLLUSKS 

Specimens of Hyalopecten aff. H. randolphi from other horizons examined

41

Locality Specimens Locality Specimens

Standard Oil Co. Bolsa No. 31, 

Huntington Beach field, 

depth 3,086 to 3,092 feet. 

U. S. G. S. locality 13905. 

Miocene.

Standard Oil Co. Schumacher

. No. 1, Huntington Beach

field, depth 4,430 to 4,44.0

feet. U. S. G. S. locality

13902. Miocene.

Same well, depth 4,4.40 to 4,453 

feet. U. S. G. S. locality 

13902b. Miocene.

\ Right and left valves of medium size and corresponding 

impressions. Undulations 

strong.

Right valve of medium size 

superimposed on interior of 

left valve of medium size 

(probably sheared paired 

specimen). Undulations 

strong.

Part of large left valve; parts 

of right and 2 left valves and 

impressions. Undulations 

strong.

Marine Oil Co. Strong No. 1, 

near Nbrwalk, depth 3,535 

feet. U. S. G. S. locality 

13886. Pico formation.

Southern California Drilling 

Co. Ma'tteson No. 1, near El 

Segundo, depth 2,081 feet. 

U. S. G. S. locality 13912. 

Pico formation.

Imperfect large right valve. 

Undulations moderately 

strong.

Large left valve (figured). 

Impression of part of right 

valve showing sculpture on 

anterior ear (figured). Incomplete right valve (figured). Impression of part 

of right valve. Undulations 

moderately strong to weak.

Hyalopecten (Dclcctopecten) aff. H. randolphi tillamookensis

(Arnold)

Pccton (Pscudamusium) Vancouver'ensis fernandoensis Hertlein, 

Soil them .California Acad. Sci. Bull., vol. 24, pp. 43, 44, 

pi. 4, figs. 6, 7, 1925. Ventura River; Fernando, Pliocene 

(type). Well at Signal Hill; lower Fernando, lower 

Pliocene (paratype).

Peclen (Pseudamussium) pedroanus (Trask) variety vancouverensis Whiteaves. Grant and Gale (part), San Diego Soc. 

Nat. History Mem., vol. 1, p. 238, 1931.

A Delectopecten, allied to tillamookensis, of medium 

size or moderately large. Concentric undulations moderately strong to weak. Sculpture consisting of fine 

radial ribs and concentric threads; minute knobs at the 

intersections. Right anterior ear sculptured with 5 to 7 

radial ribs and concentric threads. Camptonectes 

sculpture as in Hyalopecten aff. H. randolphi.

Length 22.7 millimeters, estimated height 22 millimeters (left valve; from a horizon assigned to Pico 

formation). Length 12.5 millimeters, height about 7 

millimeters (left valve).

Exteriors generally have only a thin, veneer of inner 

shell substance preserved. Parts of the entire shell are 

preserved on some specimens, and the sculpture shows 

through the'thin translucent shell.

It has not been determined whether fernandoensis is 

differentiated from tillamookensis. The fossils from the 

Los Angeles Basin are considerably smaller than large 

shells of tillamookensis. Some of the fossils have 

stronger concentric undulations than Recent shells, but

the strength of the undulations is variable in both fossil 

and Recent specimens.

The type locality of fernandoensis, on the south flank 

of the Ventura anticline, represents strata of upper 

Pliocene age. The specimens from the Los Angeles 

Basin are from core material representing horizons 

in the Repetto and Pico formations. Hertlein recorded 

fernandoensis from a well in the Long Beach field at a 

depth determined by Wissler as representing a horizon 

near the top of the Repetto formation. In the material 

at hand specimens from the Repetto formation are 

smaller (length 9.2 to 12.5 millimeters) than those from 

the Pico formation (length 14.3 to 22.5 millimeters).

Two specimens from the upper Miocene, or a horizon 

near the contact between Miocene and Pliocene, have 

.exceptionally strong concentric undulations and are 

identified as H. cf. H. pedroanus. One (pi. 6, fig. 1; 

St. Helen's Petroleum Co. P. & B. No. 6, Montebello 

field, depth 5,704 feet; U. S. G. S. locality 13870; from 

a horizon near contact between Miocene and Pliocene) 

has a length of 30.5 millimeters and is much larger than 

:the specimens from the Repetto and Pico formations. 

It has faint radial ribs near the lower margin of part 

of the shell. The other (pi. 6, fig. 2; Graham & Loftus 

Oil Co. No. 1, East Coyote field, depth 5,592 to 5,615 

'feet; U. S. G. S. locality 13872; Miocene) has a length 

of 17 millimeters and strong radial ribs. Right anterior 

ears are not preserved in the material from either well.

In addition to the Repetto records in the following 

table, Wissler has identified H. aff. H. randolphi 

tillamookensis in a core from A. N. Macrate Gray No. 1, 

;Rosecrans field, depth 5,620 feet.

Specimens of Hyalopecten aff. H. randolphi tillamookensis from Repetto formation examined

Locality

Julian Oil. Co. Farnsworth No, 

2, Huntington Beach field, 

depth 2,081 feet. . U. S. G/ 

S. locality 13908. 

Same well, depth- 2,135 feet! 

U. S. G. S. locality 13908a.

Specimens

Left valve of medium size and 

impression (figured) ; most of 

shell on impression.

Interior .of small right valve; 

most' of shell preserved.

Locality

Huntington Signal Oil Co. 

", Hand No. 2, Huntington 

Beach field, depth 3,454 feet. 

U. S. G. S. locality 13909.

!

Specimens

Interior of small right valve; 

most of shell preserved.
42 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN 

Specimens of Hyalopecten aff. H. randolphi tillamookensis from other horizons examined

Locality Specimens Locality Specimens

Standard Oil Co. Vickers No. 1 

lease, well No. 27, Inglewood 

field, depth 1,240-1,253 feet. 

U. S. G. S. locality 13888. 

Pico formation.

Standard Oil Co. Los Angeles 

Investment No. 71, Inglewood field, depth 1,323- 

1,324 feet. U. S. G. S. locality 13891. Pico formation.

Interior of valve of medium 

size (figured). Exterior of 

parts of 2 other valves; shell 

not preserved.

Interiors and impressions of 4 

incomplete valves of medium 

size or moderately large.

Union Oil Co. Mosier No. 1, 

Rosecrans field, depth 3,000 

feet. U. S. G. S. locality 

13894. Pico formation.

Left valve of medium size and 

impression; most of the shell 

on the impression. Greater 

part of distorted left valve 

of medium size. Strongly 

sculptured left valve of medium size; shell not preserved.

Family OSTREIDAE

Genus OSTREA Linne

Ostrea vespertina Conrad

Plate 9, figure 5 

Localities in coastal region of California and San Joaquin Valley

Ostrea vespertina Conrad, Gabb (part), California Geol. Survey, 

Paleontology, vol. 2, p. 107 (list), 1869. Santa Barbara; 

Pliocene.

Cooper (part), California State Min. Bur. 7th Ann. Rept., 

p. 256 (list), 1888. Santa Barbara, San Fernando; 

Pliocene.

Cooper, in Watts, California State Min. Bur. Bull. 11, p. 

80 (list), 1897. Los Angeles oil wells.

Arnold, U. S. Geol. Survey Bull. 396, pp. 31 (list), 35 (list), 

39 (list), 42 (discussion), 43 (discussion), 44 (discussion), 

77-79, pi. 24, figs. 4, 5, 1909 [1910]. Coalinga district; 

Etchegoin formation, uppermost Miocene. [Figured 

specimens from Pecten coalingaensis zone, now referred to 

San Joaquin formation; Pliocene.]

Arnold, in Arnold and Anderson, U. S. Geol. Survey Bull. 

398, pp. 126 (list), 129 (list), 132 (list), 137 (discussion), 

138 (discussion), 139 (discussion), pi. 46, figs. 4, 5, 1910. 

Coalinga district; Etchegoin formation, uppermost Miocene. [Figured specimens from Pecten coalingaensis zone, 

now referred to San Joaquin formation; Pliocene.

Smith, California Acad. Sci. Proc., 4th ser., vol. 3, pp. 167 

(list), 172 (list), 1912. Etchegoin, upper Miocene.

Nomland, California Univ., Dept. Geology, Bull., vol. 10, 

p. 219 (list), table opposite p. 230 (list), 1917. Coalinga 

district; Etchegoin, Pliocene.

Nomland, California Univ., Dept. Geology, Bull., vol. 10, pp. 

299 (list), 300 (list), 302 (list, "cf."), 1917. Coalinga district; Santa Margarita, Miocene.

Gester, 1917, California Acad. Sci. Proc., 4th ser., vol. 7, p. 

224 (mentioned), 1917. Blown out of well at McKittrick; 

Pliocene.

Smith (part), California Acad. Sci. Proc., 4th ser., vol. 9, p. 

147 (list), 1919. Etchegoin-Jacalitos; Pliocene.

Woodring, California Acad. Sci. Proc., 4th s.er., vol. 19, pp. 

59 (list), 62 (list), 1930. North of Simi Valley, Temescal 

Canyon; Pliocene.

Woodring, in Hoots, U. S. Geol. Survey Prof. Paper 165, p. 

119 (list), 1931. Temescal Canyon; San Diego formation, 

middle or upper Pliocene.

Grant and Gale (part), San Diego Soc. Nat. History Mem,, 

vol. 1, pp. 30 (discussion), 34 (discussion), 152-153, pi. 12, 

figs, la, 1&, 1931. Figured specimen from Holser Canyon; 

San Diego zone, middle Pliocene.

Grant, in Soper and Grant, Geol. Soc. America Bull., vol43, p. 1057 (list), 1932 (1933). Third Street tunnel, Los

Angeles; middle Pliocene [Arnold's record of 0. veatchii]. 

Ostrea veatchii Gabb. Dall, U. S. Nat. Mus. Proc., vol. 1, p. 11

(list), 1879. San Diego. 

Dall, U. S. Nat. Mus. Proc., vol. 1, p. 29 (list), 1879. 10

miles north of San Diego. 

Ashley, California Acad. Sci. Proc., 2d ser., vol. 5, p. 338

(list), 1895. San Fernando Pass; Merced series. 

Watts, California State Min. Bur. Bull. 19, p. 222 (list, "?"),

1900. Piru Creek and vicinity; middle Neocene. 

Arnold, California Acad. Sci. Mem., vol. 3, p. 63 (list)

("veatchi ?"), 1903. San Diego; Pliocene. 

Osmont, California Univ., Dept. Geology, Bull., vol. 4, p. 94

(Ashley's list), 98 (list), 1905. 5 miles northeast of

Camulos; probably Pliocene (p. 100). 

Arnold (part), U. S. Geol. Survey Prof. Paper 47, pp. 28

(list), 91 (list), 116 (list), 123 (list), 1906. Pacific Beach,

near San Diego; Pliocene. Third Street tunnel, Los

Angeles; Pliocene. 

Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 527 (list), p. 544,

pi. 49, fig. 1, 1907. Third Street tunnel, Los Angeles;

middle Fernando formation, lower Pliocene. [Figured

specimen from San Diego.] 

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull.

309, pp. 24 (list), 107 (list), 152 (list), 153 (list), 250, pi.

39, fig. 1, 1907. Near Camulos; Fernando formation,

Pliocene. Puente Hills; Fernando formation, Pliocene.

Third Street tunnel, Los Angeles; Fernando formation,

lower Pliocene. Los Angeles oil wells; Pliocene. [Figured specimen from San Diego.] 

Arnold, Smithsonian Misc. Coll., vol. 50, no. 1781, pp. 423

(list), 445, pi. 56, fig. 10, 1907. Santa Maria district;

Fernando, upper Miocene-Pliocene-Peleistocene. 

Arnold, in Arnold and Anderson, U. S. Geol. Survey Bull. .

322, pp. 58 (list), 148, pi. 23, fig. 10, 1907. Santa Maria

district; Fernando, base of Pliocene. 

Smith, California Acad. Sci. Proc., 4th ser., vol. 3, pp. 167

(list), 172 (list), 1912. Upper Miocene to Pliocene. 

English, California Univ., Dept. Geology, Bull., vol. 8, p.

210 (list), 1914. Holser Canyon; lower Fernando, Pliocene. 

Dievendorff, in Collom, California State Min. Bur. Bull.

82, pp. 212 (list), 213 (list) ("veatchi"), 1918. Santa

Maria district; Fernando, Pliocene. 

Smith (part), California Acad. Sci. Proc., 4th ser., vol. 9

("veatchi"), pp. 146 (list), 147 (list), 150 (list, part),

151 (list), 152 (list), 166 (discussion), 1919. Pliocene. 

Kew, U. S. Geol. Survey Bull. 753, pp. 78 (list), 88 (list),

1924. Holser Canyon; Pico formation, Pliocene.

Browns Canyon; Saugus formation, Pliocene.
MOLLUSKS 43

Carson, Southern California Acad. Sci. Bull., vol. 24, pp.

31 (list), 32 (2 lists), 1925. Brea Canyon, Puente Hills,

Holser Canyon, Gavin Canyon; Fernando formation,

lower Pliocene. 

English, U. S. Geol. Survey Bull. 768, p. 43 (Arnold's list),

1926. Puente Hills; Fernando group, Pliocene. 

Carson, Southern California Acad. Sci. Bull., vol. 25, pp. 49

(list), 51 (2 lists), 55 (list), 56 (list), 57 (list), 1926.

Fugler's Point, half a mile north of Schuman, Elsmere

Canyon; Fernando formation, lower Pliocene. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol.

43, p. 1057 (Arnold's list), 1932 (1933). Third Street

tunnel, Los Angeles; middle Pliocene.

Localities in Colorado Desert

Oslrea vesperlina Conrad, Acad. Nat. Sci. Philadelphia Jour., 

2d ser., vol. 2, p. 300, 1854. Near San Diego; Miocene.

Meek, Smithsonian Misc. Coll., no. 183, p. 3 (list), 1864. 

"Con." [? error for Calif.]

Conrad, in Blake, Preliminary report, U. S. Pacific I?,. R. 

Expl., app., pp. 7 (list), 15, 1855. Carrizo Creek; 

Miocene.

Blake, U. S. Pacific R. R. Expl., vol. 5, pt. 2, pp. 108 (mentioned), 122 (mentioned), 175 (mentioned), 176 (mentioned), 235 (mentioned), 351 (list), 352 (list), 1857. 

Carrizo Creek.

Conrad, idem, pp. 317 (mentioned), 319 (list, "nov. sp."), 

325-326, pi. 5, figs. 36-38, 1857. Carrizo Creek; Miocene.

Conrad, in Emory, Report on the United States and Mexican boundary survey, vol. 1, pt. 2, p. 160, pi. 17, figs. 

la-Id, 1857. Carriso Creek and near San Diego; Miocene.

Carpenter, British Assoc. Adv. Sci. Rept. for 1863, p. 590 

("resembles 0. lurida var."), 1864. Colorado Desert; 

Miocene.

Gabb (part), California Geol. Survey, Paleontology, vol. 2, 

p. 107 (list), 1869. Colorado Desert; Pliocene.

Heilprin, in White, U. S. Geol. Survey 4th Ann. Rept., 

p. 315, pi. 71, figs. 2-4, 1884. Carrizo Creek; Miocene 

(Conrad), Pliocene (Gabb).

Marcou, U. S. Nat. Mus. Proc., vol. 8, p. 341 (list, "types, 

U. S. Nat. Mus. no. 9832"), 1885.

Cooper (part), California State Min. Bur. 7th Ann. Rept., 

p. 256 (list), 1888. West of Colorado Desert, San Diego 

County; Pliocene.

Orcutt, California State Min. Bur. 10th Ann. Rept., p. 917 

("described from Carrizo Creek"), 1890.

Dall, Wagner Inst. Sci. Philadelphia Trans., vol. 3, pt. 4, 

p. 685 ("types in Nat. Mus."), 1898.

Schuchert, U. S. Nat. Mus. Bull. 53, pt. 1, p. 475 (list, 

"cotypes U. S. Nat. Mus. no. 9832"), 1905. Carrizo 

Creek and near San Diego; Miocene.

Arnold, U. S. Geof. Survey Prof. Paper 47, pp. 22 (list), 61 

(mentioned), 1906. Carrizo Creek; Miocene.

Kew, California Univ., Dept. Geology, Bull., vol. 8, pp. 44 

(mentioned), 45 (mentioned), 46 (list), 1914. Carrizo 

Creek region; Carrizo formation, age not definitely 

determined.

Smith (part), California Acad. Sci. Proc., 4th ser., vol. 9, 

p. 153 (list), 1919. Carrizo; Pliocene.

Hanna, California Acad. Sci. Proc., 4th ser., vol. 14, pp. 

468-469, pi. 26, figs. 4-7, 1926. Coyote Mountain; 

Pliocene.

Woodring, Carnegie Inst. Washington Pub. 418, pp. 9 

("probably different species"), 11 (" vesperUna"), 1931. 

Imperial formation; Miocene.

Localities in Lower California

Ostrea veatchii Gabb, California Geol. Survey, Paleontology, vol. 

2, pp. 34-35, 1866; pp. 60-61, 106 (list), pi. 11, fig. 59, pi. 

17, fig. 21, 21a, 1869. Cerros Island; probably Miocene 

(p. 32), post-Pliocene (p. 106). Near Loreto; postPliocene (pp. 61, 106).

Ostrea vespertina Conrad. Jordan and Hertlein, California Acad. 

Sci. Proc., 4th ser., vol. 15, p. 212 (list), 1926. Maria 

Madre Island; Pliocene.

Jordan and Hertlein, California Acad. Sci. Proc., 4th ser., 

vol. 15, pp. 417 (list), 420 (list), 428-429, 1926. Cedros 

Island; Pliocene.

Hanna and Hertlein, California Acad. Sci. Proc., 4th ser., 

vol. 16, pp. 141 (list), 145 (list), 146 (list), 149 (list), 1927. 

Localities bordering Gulf of California; Pliocene.

Oslrea haitensis Sowerby subsp. vespertina Conrad. Stewart, 

Acad. Nat. Sci. Philadelphia Special Pub. 3, pp. 128-129, 

pi. 14, fig. 4, 193Q. Cedros Island; Pliocene.

A broken strongly plicate left valve in Hamlin's 

collection from the Third Street tunnel represents an 

apparently elongate-ovate oyster (height 66.6 millimeters, restored length about 50 millimeters). It 

closely resembles strongly plicate left valves from San 

Diego referred to 0. vespertina or veatchii.

Ostrea vespertina was one of the first fossils to be 

described from California. It was described in 1854 

on the basis of material collected "near San Diego" by 

Le Conte. The locality record is equivocal, and both 

San Diego and Carrizo Creek, which lies in the Colorado 

Desert 65 miles east of San Diego in a direct line, have 

been claimed as the type locality. Through the kindness of Dr. H. A. Pilsbry a lot of nine specimens in the 

collections of the Philadelphia Academy of Natural 

Sciences (no. 13366), which is regarded as the type lot, 

is available for examination. The locality and collector 

are not recorded on the label, which doubtless was 

written after Conrad's time. The largest specimen, an 

incomplete right valve riddled by a boring sponge (?) 

shown on plate 8, figures 3, 8, agrees with Conrad's 

dimensions ("from beak to base 1%; transversely 1%" 

[inches]) and is selected as the lectotype. The type 

lot represents a small ovate or ovate-falcate oyster that 

agrees in characters with the oyster found at Carrizo 

Creek, and the specimens have the brown color and 

vitreous luster of Carrizo Creek specimens. The collector presumably was John L. Le Conte, who traveled 

down Carrizo Cjreek in 1850 to examine the mud 

volcanoes at Salton Sea and in his account mentioned 

oyster shells observed along Carrizo Creek but left no 

record of having collected specimens. 28 "Near San 

Diego" would not be an unreasonable description for 

Carrizo Creek at the tune when this oyster was described. Conrad's later citation "Carriso Creek and 

near San Diego" indicates that he thought he had this 

species from two localities, and this citation has sups' Le Conte, J. L., Account of some volcanic springs in the Desert of the Colorado in 

southern California: Am. Jour. Sci., 2d ser., vol. 19, p. 3,1855.
44 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

ported the literal interpretation of "near San Diego" 

that is the current one.

The plicate oysters in the Miocene and Pliocene of 

California and Lower California appear to represent two 

closely related poorly defined groups ^(1) large circular-ovate oysters; (2) ovate, ovate-falcate, or elongate 

oysters of small or medium size. A satisfactory nomenclature for these oysters has not been worked out. 

Large circular-ovate oysters are not recorded from the 

Pliocene of the coastal region of California and the San 

Joaquin Valley, but aside from the difference in size 

some specimens resemble the large circular-ovate form. 

The plicate oysters from the coastal region and the San 

Joaquin Valley appear to resemble vespertina, and that 

name is used for them.

The coastal vespertina is of medium size, and almost 

any collection of fair size includes elongate specimens. 

A collection from locality 2474 (second bench back on 

mesa, three-fourths mile northeast of Pacific Beach, 

near San Diego) consists of 38 valves, associated 

with Pecten stearnsii, Lyropecten cerrosensis, and Patinopecten healeyi. In outline they range from ovate to 

ovate-falcate; a few are markedly elongate. The largest 

has a length of 66.4 millimeters and a height of 84.4 

millimeters. Left valves have relatively few (5 to 7) 

plications; right valves are strongly to weakly plicate, 

and a few are only undulate. The inner margin below 

the ligament area is strongly fluted, weakly fluted, or 

smooth. Three corresponding right and left valves 

from locality 2272 (mesa between San Diego and National City) have stronger and more numerous plications, and right valves are as strongly plicate as left 

valves. The left valve from this locality figured by 

Arnold 29 is more elongate and larger than the others, 

except the corresponding right valve. The inner margin below the ligament area is smooth or weakly fluted. 

Despite the outline the lower margin of the shell figured 

by Arnold is not broken. An elongate left valve and a 

paired small ovate shell from locality 2661 (Crystal 

Springs) are strongly plicate. A small left valve from 

Pacific Beach (locality 2458) is ovate and moderately 

plicate; three ovate right valves from the same locality 

but under a different locality number (2657) are undulate.

In addition to localities near San Diego representing 

the Pliocene San Diego formation, the coastal oyster 

is recorded as vespertina or veatchii from Pliocene localities in the Puente Hills, Los Angeles, and Temescal 

Canyon (all around the borders of the Los Angeles 

Basin), in the hills north of Simi Valley in Ventura 

County, in the Ventura Basin, in the Santa Maria 

Basin, and in San Joaquin Valley. A right valve from 

an indefinite locality near Newhall, in the eastern part

w Arnold, Ralph, U. S. Nat. Mus. Proc., vol. 32, pi. 49, fig. 1,1907 (as Ostrea veatchii 

Qabb). Eldridge, O. H., and Arnold, Ralph, U. S. Qeol. Survey Bull. 309, pi. 39, 

fig. 1, 1907 (as Ostrea veatchii Qabb).

of the Ventura Basin close to San Fernando Pass (locality 3514), has a circular-ovate outline and exceptionally deep plications (incomplete length 59 millimeters, 

height 67 millimeters). It closely resembles the Lower 

California form (veatchii). An elongate paired shell in 

the same collection also. has very deep plications. 

Arnold 30 figured a relatively large ovate, moderately 

plicate left valve from locality 4474, in the Santa Maria 

Basin (railroad cut 1 mile north of Schumann), where 

this species, is represented by numerous specimens, 

most of which are strongly fluted on the inner margin 

below the ligament area. A few valves are elongate, 

and some right valves are undulate. Arnold received 

from Orlando Barton a fine lot of 83 valves from the 

Pecten coalingaensis zone, now assigned to the San 

Joaquin formation, on the east side of South Dome, at 

the south end .of the Kettleman Hills (locality 4715),31 

in San Joaquin Valley, a left valve and a right valve of 

which were figured. Most of thes.e shells are ovate, 

like the figured right valve; the figured left valve, which 

is not correctly oriented, is about as strongly ovatefalcate as any other; and a few are markedly elongate. 

Left valves are strongly plicate, and all except two or 

three right valves are us strongly plicate as left valves. 

Fluted margins were not observed 'on any of the 25 left 

valves, and 17 of 52 right valves that show the inner 

margin are clearly fluted. Of these 17 only 5 are fluted 

on the anterior margin. These shells resemble strongly 

plicate shells from San Diego but are a little smaller, 

the largest having a length of 56.3 millimeters and a 

height of 71.7 millimeters. A smaller, generally less 

plicate oyster, most right valves of which are undulate 

rather than plicate, occurs in the uppermost part of the 

San Joaquin formation. It was named Ostrea vespertina var. seguens by Arnold 32 and appears to be a variety 

or subspecies of the oyster found at lower horizons in 

this region. .No character aside from smaller size is 

apparent to distinguish elongate, weakly plicate left 

valves and most right valves of vespertina seguens from 

moderately elongate shells of the modern 0. lurida 

Carpenter,33 some left valves of which are weakly plicate 

,or strongly undulate, and perhaps lurida is derived 

from this form. Modern shells from the Gulf of 

California, Lower California, and fuget Sound, labeled 

0. palmula Carpenter,34 resemble ovate or ovate-falcate

3° Arnold, Ralph, Smithsonian Misc. Coll., vol. 50, no. 1781, pi. 56,-flg. 10, 1907 (as 

Ostrea veatchii Gabb). Arnold, Ralph, and Anderson, Robert, U. S. Geol. Survey 

Bull. 322, pi. 23, fig. 10, 1907 (as Ostrea veatchii-Gabb).

ii This locality is listed'in Bull. 396 (pp. 34-36, 47) and Bull. 398 (pp. 135) 153) under 

both the Etchegoin and Tulare formations, presumably on account of the occurrence 

of fresh-water shells, which were mistaken for Tulare fossils.

3' Arnold, Ralph, Paleontology of the Coalinga district, California: U. S. Qeol. 

Survey Bull. 396, pp. 79-80, pi. 29, figs. 5, 6, 1909 [1910].

33 Carpenter, P. P., Supplementary report on the present state of our knowledge 

with regard to the Mollusca of the west coast of North America: British Assoc. Adv. 

Sci. Rept. for 1863, p. 645, 1864.

34 Carpenter, P. P., Catalogue' of the collection of Mazatlan shells in the British 

Museum, pp. 163 ("Ostreall conchaphilla var. palmula"), 550 ("the examination of 

additional specimens confirms the opinion that Oslrea.palimda is a distinct species"), 

1857. '
MOLLUSKS 45

specimens of the coastal vespertina of medium size, but 

they have an exceptionally long strongly fluted area 

on the inner margin.

The small ovate-falcate oyster from Carrizo Creek 

and other localities around the borders of Carrizo 

Mountain and nearby regions in the Colorado Desert 

was described by Conrad as vespertina, which was again 

treated as a new species in 1857 but not in 1855. Two 

left valves figured by Conrad in volume 5 of the Pacific 

Railroad reports (pi. 5, figs. 37, 38) are in the U. S. 

National Museum (no. 1854). According to a later label 

they were identified by Meek, which probably means 

that Meek recognized them as Conrad's figured specimens. Five less satisfactory specimens, labeled "identified by Conrad", are under the number 8397. Dall 

added "types" to the label; therefore, these specimens 

were claimed by Dall as the "types" of vespertina and 

were identified as 0. haitensis Sowerby.35 The wellexecuted drawings by Meek in Emory's report on the 

geology of the Mexican boundary survey are based on 

a left and a right valve also in the National Museum 

(no. 9832). They were listed by Marcou as "types" .and 

by Schuchert as "cotypes" of vespertina. Another drawing of the same left valve was published by Heilprin. : 

This oyster is a little smaller than the coastal vespertina. 

It also is generally more distinctly ovate-falcate. 

Ovate specimens that show no suggestion of a falcate 

outline are rare, and the few elongate specimens are 

more distinctly falcate than elongate coastal specimens. 

The posterior margin of the lectotype (pi. 8, figs. 3, 8) 

is broken and it may have had a more ovate-falcate 

outline than is apparent. Two complete right valves 

from Carrizo Creek (locality 3921; Barrett's oil well 

[on south side of Carrizo Creek], about 20 miles north 

of Mexican boundary) are shown in plate 8, figures 1, 

2, 4, 9.. Left valves are strongly plicate, and with few 

exceptions right valves also are plicate, aside from an 

undulate or smooth area extending downward from the 

umbonal region, but generally are not so strongly, 

plicate as left valves. Most specimens from Carrizo 

Creek and the coastal region are twisted clockwise 

when viewed in attached position; a few are counterclockwise. The largest valve in a lot of 40 from locality 

3921 has a length of 48.7 millimeters and a height of 

61.7 millimeters, being thus exceptionally large' for this 

form. Left and right valves from this locality are 

strongly fluted on the inner margin below the ligament 

area, but this character is not uniform; some lots consist of weakly fluted or smooth specimens. Of the shells 

at hand from the coast and San Joaquin Valley the. 

Carrizo Creek form is most similar to the one from the 

Pecten coalingaensis zone of the Kettleman Hills, one of 

the similarities that led Arnold to consider the forma88 Dall, W. H., Contributions to the Tertiary fauna of Florida: Wagner Inst. Sci. . 

Philadelphia Trana., vol. 3, pt. 4, p. 086, 1898.

tions at these localities to be of about the same, age.36 

Some specimens from the Kettleman Hills are as distinctly ovate-falcate as those from Carrizo Creek, but 

an ovate outline is general, and a few specimens are 

elongate-ovate. The Carrizo Creek oyster is abundant 

in the upper part of the Imperial formation associated 

with Aeguipecten circularis deserti and Anomia subcostata, an association indicating brackish water. It is 

more similar to the coastal and San Joaquin vespertina 

than to any described Miocene or Pliocene oyster from 

the Pacific coast.

0. veatchii was considered identical with vespertina by 

Dall, by Jordan and Hertlein, who had topotype material from Cedros Island, and by Stewart. Gabb's 

specimens of veatchii are available through the kindness of Dr. Pilsbry. The left valve from Cedros Island 

(or Cerros Island), off Lower California, identified by 

Stewart as the holotype, agrees in outline and dimensions with Gabb's figure; differences in details of 

sculpture probably are due to free drawing. This 

left valve is strongly plicate and of medium size (length 

about 69 millimeters, height 75.5 milhmeters). As 

noted by Stewart, the upper anterior margin is broken. 

Gabb's drawing of this part of the shell may be a reconstruction. The corresponding right valve, which also 

is strongly plicate, is more complete (length 67 millimeters, height 73 millimeters). A smaller left valve 

also is circular-ovate and strongly plicate. An exceptionally deep right valve is irregularly undulate and 

probably represents some other form. The much 

larger circular-ovate left valve later figured by Gabb is 

in the same tray, but whether it came from Cedros 

Island or is one of the large specimens from the gulf 

side of Lower California described at the time when it 

was figured is not clear. The shell is very thick, and 

the plications are not so deep as on the holotype and 

corresponding right valve (length 123 millimeters, 

height 131 milhmeters, maximum thickness about 42 

milhmeters). The characters of large suites of specimens from Cedros Island have not been described. If 

the holotype and corresponding right valve are representative, veatchii has deeper plications than most 

specimens of the coastal vespertina and has a more 

circular-ovate outline than most coastal specimens; 

and if the large left valve is conspecific, veatchii reaches 

a much larger size than the coastal vespertina. Some 

strongly plicate coastal specimens, however, such as 

those from localities near San Diego (2272) and Newhall (3514), closely resemble small specimens of veatchii.

 0. veatchii apparently belongs in the group of large, 

circular-ovate plicate oysters that was widespread in 

the Miocene. This group of oysters is found in the 

Miocene of the Caribbean region, where it is represented

"Arnold, Ralph, Paleontology of the Coalinga district, California: U. S. Qeol. 

Survey Bull. 396, pp. 44, 78, 1909 [1910].
46 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

by 0. haitensis Sowerby,37 from the Dominican Republic, and 0. gatunensis Brown and Pilsbry,38 from the 

Gatun formation of the Canal Zone. Gabb considered 

veatchii identical with haitensis when he became acquainted with haitensis as a result of his explorations 

in the Dominican Republic.39 Dall also considered 

veatchii identical with haitensis, and Stewart cited 

vespertina (-f- veatchii) as a subspecies of haitensis. 

Though now extinct in the Caribbean region, this group 

of oysters is still living in the Gulf of California, where 

it is represented by the oyster that Dall named 0. 

fisheri.40 For no apparent reason several small shells 

and a large one from the Gulf of California were differentiated by Dall as 0. veatchii.*1

0. heermanni Conrad,48 from the Imperial formation 

of the Colorado Desert, is another representative of this 

group of large circular-ovate plicate oysters. The type 

of heermanni, according to a communication and photograph from Dr. Pilsbry, is a large, thick, weakly plicate 

right valve (Acad. Nat. Sci. Philadelphia no. 13367). 

Tne large oyster figured by Gabb as veatchii appears to 

be indistinguishable from the strongly plicate form of 

heermanni, which is the usual form. 0. heermanni is 

found in sandstone and limestone near the base of the 

Imperial formation and at places in the upper part of 

the formation in association with the abundant small 

ovate-falcate vespertina. These two forms are under 

the same locality number in one of Bower's early collections (locality 3921, Barrett's oil well, about 20 miles 

north of Mexican boundary, on south side of Carrizo 

Creek), and in another of his collections (locality 3919, 

east end of Carrizo Mountain) vespertina is under the 

same number as species characteristic of the lower part 

of the Imperial formation. Small shells varying in 

outline from circular-ovate to ovate-falcate are associated with large specimens of heermanni and some of 

intermediate size in another of Bower's collections 

(locality 3922, head of Garnet Canyon [on north slope 

of Carrizo Mountain]) from the lower part of the Imperial formation. Some of these small specimens 

(length 37.8 to 44.4 millimeters) have fewer and broader 

plications than vespertina, but some ovate-falcate speci87 Sowerby, Q. B., Description of new species of fossil shells found by J. S. Heniker, 

Esq.: Qeol. Soc. London Quart. Jour., vol. 6, p. 53,1850.

f8 Brown, A. P., and Pilsbry, H. A., Fauna of the Gatun formation, Isthmus of 

Panama: Acad. Nat. Sci. Philadelphia Proc., vol. 63, p. 366, pi. 29, figs. 1, 2, 1911. 

The type is more ovate than a paired shell at Washington.

« Gabb, W. M., On the topography and geology of Santo Domingo: Am. Philos. 

Soc. Trans., new ser., vol. 15, pp. 257-258,1873.

« Dall, W. H., Notes on West American oysters: Nautilus, vol. 28, p. 1,1914; new 

name for 0. jacobaea Rochebrune, 1895 (Mus. hist. nat. Paris Bull., vol. 1, p. 241), 

not Linnfi, 1758. Lamy (Jour. Conchyliologie, vol. 57, pp. 218-219, 1909) considered 

jacobaea identical with O. cumingiana Dunker (Zeitschr. Malakozoologie, year 3, 

p. 48, 1846; Philippi, Abbildung und Beschreibungen neuer oder wenig gekannter 

Conchylien, vol. 2, p. 81, Ostrea, pi. 1, figs. 1-4,1847), which he cited as a variety of the 

oriental O. sinensis Gmelin. 0. cumingiana was originally described from an unknown locality.

<i Dall, W. H., idem, pp. 1-2; Summary of the marine shell-bearing mollusks of the 

northwest coast of America: U. S. Nat. Mus. Bull. 112, p. 17,1921.

4J Conrad, T. A., Description of eighteen new Cretaceous and Tertiary fossils: 

Acad. Nat. Sci. Philadelphia Proc., vol. 7, p. 267,1855. Hanna, G. D., Paleontology 

of Coyote Mountain, Imperial County, Calif.: California Acad. Sci. Proc., 4th ser., 

vol. 14, p. 467, pi. 22, figs. 7, 8, pi. 23, flgs. 1, 2, 1926.

mens (length 27.3 to 40.7 millimeters) are indistinguishable from that form in outline, plication, fluting of the 

inner margin, and character of the ligament area. The 

possibility that two species of plicate oysters are represented at this locality seems to be remote. These small 

specimens indicate that vespertina from the upper part 

of the Imperial formation is a form of heermanni and 

that heermanni should be treated as a nomenclatural 

variety of vespertina. Nevertheless, it does not seem 

desirable to unite heermanni with vespertina, for typical 

heermanni is readily distinguishable from any lot of 

small oysters from the upper part of the Imperial formation. Dall considered veatchii, heermanni, and vespertina identical with haitensis, and Stewart suggested 

that the small Carrizo Creek form is the young of heermanni. Though a satisfactory nomenclature has not 

been worked out for the plicate oysters named haitensis, 

vespertina, heermanni, veatchii, Jisheri, and gatunensis, 

it may be advantageous to differentiate the coastal 

vespertina, for large circular-ovate, plicate oysters are 

not recorded in the coastal and San Joaquin Valley 

Pliocene. Loel and Corey considered a large plicate 

Vaqueros oyster a variety of vespertina**

The distribution of 0. virleti Deshayes and similar 

species in the Mediterranean region and in the Orient 

has been discussed by Davies,44 who included vespertina 

in the virleti group, and by Cox,45 who pointed out the 

similarity of haitensis to virleti.

The type of Ostrea 4e is the Recent European 0. edulis 

Linne. Oysters with strong plications on both valves 

are generally assigned to the subgenus Lopha.*7

The Imperial formation of the Colorado Desert is 

considered Miocene by some workers 48 and Pliocene by 

others.49 Mansfield 50 has called attention to the similarity of fossils considered of Pliocene age, recovered 

from limestone dug up along the Tamiami Trail, in

« Ostrea vespertina Conrad loeli Hertlein. Loel and Corey, California Univ., D ept 

Geol. Sci., Bull., vol. 22, pp. 193-194, pi. 16, figs, la, Ib, 2, pi. 17,1932.

44 Davies, A. M., in Wayland, E. J., and Davies, A. M., The Miocene of Ceylon: 

Geol. Soc. London Quart. Jour., vol. 79, pp. 588-589,1923. Davies, A. M., Tertiary 

faunas, vol. 2, pp. 160-161, London, 1934.

<s Cox, L. R., Neogene and Quaternary Molluscs from the Zanzibar Protectorate: 

Report on the paleontology of the Zanzibar Protectorate, pp. 67-69, London, 1927.

49 Linne', C.,Systema naturae, ed. 10, p. 696,1758. Subsequently designated type(Children, Lamarck's genera of shells: Quart. Jour. Sci., vol. 15, p. 43,1823; cited from Keiinard, Salisbury, and Woodward, Smithsonian Misc. Coll., vol. 82, no. 17, p. 15,1931).

« RSding, P. F., in Bolten, J. F., Museum Boltenianum, pt. 2, p. 168, 1798. Subsequently designated type (Dall, Wagner Inst. Sci. Philadelphia Trans., vol. 3, pt. 

4, p. 672, 1898), Ostrea crista-galli (Linn6) (cited by Roding as crista galli Gmeliu), 

Recent, Indian Ocean.

« Dickerson, R. E., Ancient Panama Canals: California Acad. Sci. Proc., 4th ser., 

vol. 7, pp. 200-201,1917. Woodring, W. P., Distribution and age of the marine Tertiary deposits of the Colorado Desert: Carnegie Inst. Washington Pub. 418, pp. 14-25, 

1931. Bramkamp, R. A.-, Molluscan fauna of the Imperial formation of San Gorgonio 

Pass [abstract]: Geol. Soc. America Proc., 1934, p. 385, 1935.

« Vaughan, T. W., The reef-coral fauna of Carrizo Creek, Imperial County, Calif., 

and its significance: U. S. Geol. Survey Prof. Paper 98, p. 368,1917. Kew, W. S. W., 

Cretaceous and Cenozoic Echinoidea of the Pacific coast of North America: California Univ., Dept. Geology, Bull., vol. 12, pp. 32, 33, 56, 59, 60, 61,137,1920. Hanua, 

G. D., Paleontology of Coyote Mountain, Imperial County, Calif.: California Acad. 

Sci. Proc., 4th ser., vol. 14, p. 434,1926. Strong, A. M., Hanna, G. D., and Hertlein, 

L. G., Marine Mollusca from Acapulco, Mexico, with notes on other species: California Acad. Sci. Proc., 4th ser., vol. 21, p. 125,1933.

M Mansfield, W. C., Pliocene fossils from limestone in southern Florida: U. S. 

Geol. Survey Prof. Paper 170, p. 46,1932.
MOLLUSKS 47

southern Florida, with species from the Imperial formation. Of the mollusks compared with Imperial species 

all except Pecten (Lyropecten} tamiamiensis compare 

favorably with West Indian and Central American 

Miocene species (Ostrea tamiamiensis with 0. haitensis 

Sowerby and allies, Pecten (Nodipecten) pittieri with 

Lyropecten (Nodipecten) nodosus (Linn6), Pecten (Plagioctenium) evergladensis with Aequipecten (Plagioctenium) 

levicostatus (Tonla) and allies). 51 The hinge of Pecten 

tamiamiensis is not exposed, but it appears to be a 

moderately inflated Lyropecten. The strong midrib 

filling the interspaces points to alliance with the California Miocene L. estrellanus (Conrad). (See discussion 

under L. cerrosensis.) The Imperial L. mediacostatus 

(Hanna), 82 with which tamiamiensis was compared, is a 

species of the estrellanus stock, as Hanna recognized; 

and it has been considered the same as L. estrellanus 

catalinae (Arnold),53 described from beds on Santa 

Catalina Island referred to the Miocene. There is no 

record of a pecten similar to tamiamiensis in the Miocene 

of Central America, the West Indies, or the Atlantic 

coast. Pecten interlineatus Gabb, 54 a Miocene species 

from the Dominican Republic that has a moderately 

strong midrib, is probably an Aequipecten. . Inasmuch 

as estrellanus and its allies occur in the California 

Miocene, tamiamiensis is a migrant from California, if 

it is allied to estrellanus and if it is of Pliocene age. The 

Florida species may not have any bearing on the age 

of the Imperial formation, but it opens an interesting 

paleogeographic problem. This species or its unknown 

predecessor may have reached the Gulf of Mexico 

through an mteroceanic passage across Tehuantepec, 

postulated by some workers. 55

Family LIMIDAE

Genus LIMA Bruguiere

Subgenus ACESTA H, and A. Adams

Lima (Acesta) hamlini Ball

Plate 8, figures 5, 7, 10, 11

Lima hamlini Dall, Nautilus, vol. 14, pp. 15-16, 1900. Third 

Street tunnel, Los Angeles; probably Pliocene.

Arnold, U. S. Geol. Survey Prof. Paper 47, pp. 91 (list), 116 

(list), 123 (list), 1906. Third Street tunnel, Los Angeles; 

Pliocene.

Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 527 (list), 1907. 

Third Street tunnel, Los Angeles; middle Fernando formation, lower Pliocene.

Arnold, in Eldridge and Arnold, U. S. Geol. Survey Bull. 

309, p. 152 (list), 1907. Third Street tunnel, Los Angeles; 

Fernando formation, lower Pliocene.

«' Thrada (Cyathodonta) tristana Olsson, doubtfully identified in the Tamiami 

collection, is a Costa Rican Miocene species.

" Hanna, O. D., op. cit, p. 472, pi. 22, fig. 0, pi. 24, fig. 2.

" Grant, U. S., IV, and Oalo, H. R., op. cit., p. 186, 1931.

81 Soo Pilsbry, H. A., Rovision of W. M. Gabb's Tertiary Mollusca of Santo Domingo: Acad. Nat. Sci. Philadelphia Proc., vol. 73 (1921), p. 411, pi. 45, fig. 3,1922.

" Schuchort, Charles, Historical geology of the Antillean.Caribbean region, pp. 29, 

375, 378-379, pi. 15, Now York, 1935.

145500 38 1

Dall, U. S. Nat. Mus. Proc., vol. 66, art. 17, p. 18, pi. 29,

fig. 6, 1925. Pliocene clays of Los Angeles. 

Grant and Gale, San Diego Soc. Nat. History Mem., vol. 1,

p. 239 (Dall's and Arnold's records), 1931. Pliocene

clays of Los Angeles. 

Grant, in Soper and Grant, Geol. Soc. America Bull., vol.

43, p. 1057 (Arnold's list), 1932 [1933]. Third Street

tunnel, Los Angeles; middle Pliocene.

A giant Lima allied to the modern Panamanian 

agassizii. Depressed area at anterior end and posterior 

auricle sculptured with relatively strong radial ribs that 

are more closely spaced toward the center of the shell, 

the interspaces being gradually transformed into narrow 

grooves, microscopically punctated by concentric 

threads. On some specimens (pi. 8, fig. 10) subdued 

grooves continue over the central part of the shell, except 

in the umbonal region, but in most specimens (pi. 8, figs. 

5, 7, 11) they are absent on a central area of varying 

width. Ligament area not exposed.

Greatest length about 52 millimeters, height 37 

millimeters, diameter of both valves 15.8 millimeters 

(holotype). Restored greatest length about 110 millimeters, height (crushed) about 95 millimeters, diameter 

of both valves (crushed) about 31 millimeters (largest 

outcrop specimen). Greatest length about 100 millimeters, height 79 millimeters, diameter (right valve) 

about 20 millimeters (largest virtually complete outcrop 

specimen). Restored greatest length about 110 millimeters, height 94.5 millimeters (largest specimen from 

well cores).

Holotype, U. S. Nat. Mus. 495186; 4 paratypes, U. S. 

Nat. Mus. 495187.

This giant Lima has been recorded heretofore only 

from the Third Street tunnel in Los Angeles, a locality 

now inaccessible. Two poorly preserved small specimens were recently collected by W. H. Holman, of the 

Standard Oil Co. of California about two blocks east 

of the type locality; and a large specimen from the 

excavation for the Los Angeles Times Building is in the 

collection of Alex Clark, of the Shell Oil Co. Outcrop 

specimens have also been collected at Malaga Cove, on 

the west coast of the Palos Verdes Hills, on the south 

side of the Los Angeles Basin, and fragmentary remains 

too imperfect to collect were recognized in a small 

outcrop of siltstone of the Repetto formation at the 

head of the fourth ravine west of Walteria, at the north 

edge of the Palos Verdes Hills. This species is the 

most widely distributed fossil in the core collections. 

It probably has a considerable stratigraphic range in 

the Repetto formation, and a small crushed right valve 

from the Huntington Beach field (Standard Oil Co. 

Schumacher No. 1, depth 4,400 feet, U. S. G. S. locality 

13902a) is assigned to the upper Miocene. In two wells 

(Emery No. 53, in the West Coyote field, and Reyes 

No. 43, in the Dominguez field) it was recovered at two 

horizons, which, dip disregarded, are 921 feet apart in 

the Emeiy well and 706 feet in the Reyes well,
48 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

The holotype, selected by Dall for figuring, is the 

smallest of five specimens in the type lot but has more 

of the outer shell layer preserved than the others. Part 

of the shell has evidently been broken off since the 

drawing was made, and the drawing is somewhat misleading, as there are no grooves or ripples on the central 

part of the shell. The type lot, which bears the locality 

number 3322, was received at an earlier date (1900) 

than the larger lot under locality no. 3426, though both 

lots were collected by Homer Hamlin in the Third 

Street tunnel.

The thin shells of this species are generally crushed 

and distorted, and paired specimens are generally 

sheared. The brown translucent outer shell layer, 

composed of calcite, readily peels from the inner chalky 

layers, consisting of aragonite,56 and generally is absent 

on part or all of the shell. The 17 specimens from the 

type locality show more or less clearly the central part 

of the shell. On four of these specimens the radial 

grooves extend in subdued form over the central part 

except in the umbonal region; on the others they are 

absent, and the smooth area is exceptionally wide on 

some specimens. On the shells that have a smooth 

central part the grooves gradually disappear or stop 

abruptly. Outcrop specimens from Malaga Cove and 

also core specimens that show the sculpture have a 

generally wide, smooth central area.

Lima hamlini belongs in a group of thin-shelled deepwater Limas that are widely distributed in the modern 

seas, as shown in the table under the heading "Inferred 

depth range of larger fossils." It closely resembles 

L. agassizii Dall 57 but has stronger ribs at the anterior 

and posterior ends and more symmetrical grooves on 

the posterior part. The only specimen of agassizii is a 

right valve dredged by the Albatross at a depth of 322 

fathoms in the Gulf of Panama. Part of the anterior 

depressed area is pathologically infolded on this specimen. These deep-water Limas represent the subgenus 

Acesta,5S which has a larger, thinner shell than Lima 

s. s.,58a a narrower cardinal area, a more oblique ligament pit, and weak ribs instead of strong scaly ribs.

»» For the shell composition of Lima see Boggild, O. B., The shell structure of the 

mollusks: Danemark Acad. roy. sci. let., Sec. sci., 9th ser., vol. 11, p. 263, 1930.

» Dall, W. H., Notes on the giant Limas: Nautilus, vol. 16, p. 16, 1902; The Mollusca and the Brachiopoda [Albatross Rept.]: Harvard College Mus. Comp. Zoology Bull., vol. 43, no. 6, p. 407, pi. 16, fig. 1, 1908.

 » Adams, H. and A., The genera of Recent Mollusca, vol. 2, p. 558, 1858. Monotype, [Ostrea] excavata [etc.] Chemnitz (= Ostrea excavata Fabricius), Recent, Norway.

58» Bruguiere, J. G., Tableau encyclopfedique et mfithodique, Vers testacfies, vol. 2, 

p. 206, 1797 (genus without named species). Tautonymic type, Lima sguamosa 

Lamarck. Systeme des animaux sans vertebres, p. 136,1801 (=0strea lima Linne, 

cited in synonymy), Recent, Mediterranean.

Callolima 59 was proposed for Philippine species that are 

weakly sculptured and have a narrow oblique ligament 

pit even on large adults. The shape of the ligament 

pit appears to depend on the width (distance from umbo 

to lower edge of chondrophore) of the cardinal area, and 

the species that have a narrow cardinal area also have 

a narrow anterior impressed area. The sculpture of the 

type species, rathbuni, is very weak, but in bartschi it is 

variable though still relatively weak The Japanese 

goliath has a ligament pit that is less oblique than in 

excavata and weak sculpture; agassizii has a narrow 

oblique ligament pit and moderately strong sculpture. 

It appears that Callolima does not differ essentially 

from Acesta, as Thiele claimed.60 Some writers cite the 

modern deep-water Limas under the subgenus Plagiostoma J. Sowerby,61 the type of which is a giant Jurassic 

species. This Jurassic species and its allies may not 

have a closer relation to Acesta than one of family or 

generic resemblance and large size. Arkell 62 rated 

Acesta and Plagiostoma as subgenera and compared their 

characters.

No living species of Acesta is known along the Pacific 

coast north of Panama, and hamlini is the only species 

recorded from the Pliocene of the Pacific coast. Lima 

(Plagiostoma) oregonensis Clark,63 from the Oligocene 

of Oregon, is the only other described form from the 

Tertiary of this region. It evidently needs comparison 

with hamlini; according to the illustrations, it resembles 

hamlini in outline and sculpture. A giant Lima is 

represented in the Oligocene of Washington by an 

incomplete, poorly preserved specimen from locality 

4092 (Strait of Juan de Fuca, 4^ miles west of Gettysburg). Tegland 64 recorded a giant Lima from this 

region and also from Weaver's Lincoln formation. 

L. goliath has been found in the later Tertiary of Japan.65

' Bartsch, Paul, The giant species of the molluscan genus Lima obtained in Philippine and adjacent waters: U. S. Nat. Mus. Proc., vol. 45, p. 235, 1913. Originally 

designated type, Lima (Callolima) rathbuni Bartsch, Recent, Philippines.

60 Thiele, J., Familia Limidae: Systematisches Conchylien-Cabinet, vol. 7, pt. 2a, 

p. 5, 1918.

81 Sowerby, James, Mineral conchology of Great Britain, vol. 1, pp. 175-176, 1814. 

Tautonymic type, Pectinites plagiostomus [etc.] Lhuyd (= Plagiostoma gigantea J. 

Sowerby), Lias, England.

62 Arkell, W. J., Monograph of British corallian Lamellibranchia, pt. 3: Paleont. 

Soc., vol. 83, pp. 128-129, 1931.

63 Clark, B. L., Pelecypoda from the marine Oligocene of western North America: 

California Univ., Dept. Geol. Sci., Bull., vol. 15, p. 84, pi. 14, figs. 3,4,1925. Schenck, 

H. G., Nuculid bivalves of the genus Acila: Geol. Soc. America Special Paper 4, 

p. 62 (list), 1936.

e< Tegland, N. M., The gastropod genus Galeodea in the Oligocene of Washington: 

California Univ., Dept. Geol. Sci., Bull., vol. 19, p. 399, footnote, 1931.

6S Yokoyama, Matajiro, Tertiary fossils from western Hi?en: Tokyo Imp. Univ., 

Fac. Sci., Jour., sec. 2, vol. 2, p. 188, pi. 50, fig. 1,1927. (Includes earlier citations of 

fossil records.)
MOLLUSKS

Specimens of Lima hamlini from Repetto formation examined

49

Locality

Third Street tunnel, Los Angeles; 

Homer Hamlin. U. S. G. S. 

locality 3322.

Third Street tunnel, Los Angeles; 

Homer Hamlin. U. S. G. S. 

locality 3426.

100 feet northeast and 100 feet 

northwest from northeast corner 

of Second and Hill Streets, Los 

Angeles; about 4 feet above level 

of Hill Street; H. W. Holman. 

U. S. G. S. locality 13862a.

Excavation for Times Building, 

First and Spring Streets, Los 

Angeles. Collection of Alex 

Clark, Shell, Oil Co.

Malaga Cove, west coast of Palos 

Verdes Hills north limb of northern syncline near trough, 5 to 10 

feet below lower bed of volcanic 

ash in Repetto formation; W. P. 

Woodring. U. S. G. S. locality 

13838.

Malaga Cove, west coast of Palos 

Verdes Hills, north limb of syncline near trough and not more 

than 10 feet below lower bed of 

volcanic ash. Collection of Union 

Oil Co.

Standard Oil Co. Murphy Coyote 

No. 117, West Coyote field, 

depth 5,910 feet. U. S. G. S. 

locality 13875a.

Standard Oil Co. Emery No. 53, 

West Coyote field, depth 4,273 

feet. U. S. G. S. locality 13879.

Same well, depth 6,194 feet. U. S. 

G. S. locality 13879a.

Specimens

Holotype (small sheared 

paired specimen) and 4 

paratypes (2 paired 

shells, 1 right valve), 1 

left valve), all of medium size.

12 specimens, of medium 

to large size, 3 of which 

are figured (4 paired, 4 

right valves, 4 left 

valves.

Part of distorted small 

left valve; very small 

right valve.

Crushed, broken large 

paired specimen.

Small distorted right valve; 

part of right valve of 

medium size; fragment 

of large right valve.

Part of large- distorted, 

very weakly sculptured 

right valve.

Large crushed right valve 

(figured).

Impression and part of 

shell of distorted right 

valve of medium size.

Part of distorted right 

valve and impression.

Locality

Standard Oil Co. Emery No. 59, 

West Coyote field, depth 4,304 

feet. U. S. G. S. locality 13883a.

Union Oil Co. Bell No. 45, Santa Fe 

Springs field, depth 5,564 feet. 

Collection of Union Oil Co.

Union Oil Co. Bell No. 53, Santa Fe 

Springs field, depth 6,237 feet. 

U. S. G. S. locality 14012.'

Standard Oil Co. Baldwin-Cienega 

No. 105, Inglewood field, depth 

5,713 feet. U. S. G. S. locality 

13890a.

Union Oil Co. Rosecrans No. 15, 

Rosecrans field, depth 5,686 feet. 

U. S. G. S. locality 14013.

Barnsdall Oil Co. Trust No. 1, 

Rosecrans field, depth 5,760 feet. 

Collection of Union Oil Co.

Union Oil Co. Hellman No. 17, 

Dominguez field, depth 4,216 

feet. Collection of Union Oil Co.

Shell Oil Co. Reyes No. 43, Dominguez field, depth 4,135 feet. 

U. S. G. S. locality 14014.

Same well, depth 4,841 feet. Collection of Union Oil Co.

Standard Oil Co. San Gabriel No. 

25, Seal Beach field, depth 4,929 

feet. U. S. G. S. locality 13901.

Standard Oil Co. Bolsa No. 7, 

Huntington Beach field, depth 

3,720 feet. U. S. G. S. locality 

13904.

Ohio Oil Co. Del Rey No. 2, Playa 

del Rey field, depth 4,001 feet. 

U. S. G. S. locality 14015.

Shell Oil Co. Barkdall No. 1, Lawndale field, depth 5,346 feet. Collection of Union Oil Co.

Standard Oil Co. Bodger No. 1, 

southeast of Lawndale field, sec. 

22, T. 3 S., R. 14 W., depth 

5,398 feet. U. S. G. S. locality 

14002.

Specimens

Greater part of right valve 

of medium size and impression.

Part of distorted right 

valve of medium size.

Part of moderately large 

right valve and impression.

Small crushed left valve 

and fragment.

Part of distorted paired 

specimen and impression of right side.

Small crushed paired specimen.

Part of right valve of 

medium size.

Part of right valve of 

medium size and impression.

Part of right valve of 

medium size.

Part of large left valve.

Part of right valve of 

medium size.

Greater part of large left 

valve and impression.

Part of crushed right valve 

of medium size; greater' 

part of shell preserved.

Large gaping paired specimen exposed in anterior 

(?) view and impression.

Through the kindness of S. G. Wissler the following 

additional records of Lima hamlini are available, based 

on specimens collected under his direction and deposited in the collection of the Union Oil Co.'s micropaleontology laboratory:

Additional specimens of Lima hamlini in collection of Union

Oil Co.

Union Oil Co. Bell No. 88, Santa Fe Springs field, depth 4,491

feet. 

Pacific Gulf Oil Co. Rosecrans No. 1, Rosecraus field, depth

5,401 and 5,407 feet. 

A. N. Macrate Gray No. 1, Rosecrans field, depth 6,025 and

6,122 feet.

Union Oil Co. Hellman No. 16, Dominguez field, depth 5,072 feet. 

Union Oil Co. Callendar No. 32, Dominguez field, depth 5,450

feet. 

Shell Oil Co. Peck No. 1, center of sec. 20, T. 3 S., R. 14 W., near

Hermosa Beach, depth 5,656 feet.

Genus L1MATTJLA S. V. Wood 

Limatula aff. L. "subauriculata (Montagu)"

Plate 8, figure 6

A small moderately elongate valve (height 7.6 millimeters, length 4.4 millimeters) from Universal^Consolidated Oil Co. Nutt No. 2, Montebello field, depth 3,627 

to 3,655 feet (U. S. G. S. locality 13871), represents a 

species of Limatula. Part of the shell is missing. The 

sculpture consists of fine radial ribs, slightly roughened 

by microscopic concentric threads. Two median ribs 

are heavier than the others and modify the interior 

outline. On the interior of the lower part of the shell, 

where the exterior is missing, a narrow midrib lies 

between the heavy ribs.

This species is probably the Recent form that ranges 

from Alaska to Lower California at depths of 14 to 984 

fathoms and is known as Lima (Limatula) subauriculata
50 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

(Montagu).66 Recent shells attain a height of 16.4 

millimeters and a length of 10.4 millimeters. They have 

one to three relatively heavy median ribs that are differentiated by strong interspaces on the interior, even 

though the ribs are not conspicuously differentiated on 

the exterior, a characteristic feature of Limatula shown 

by the fossil. This Recent form probably needs a new 

name, as it does not appear to be conspecific with the 

North Atlantic Limatula subauriculata (Montagu),67 

which is smaller and narrower. The small, narrow 

Alaskan Limatula attenuata Dall 68 appears to be more 

closely allied to subauriculata. The only Alaskan lot of 

"subauriculata" in the collections of the National 

Museum was dredged by George Willett at Forrester 

Island, west of Prince of Wales Island, at a depth of 40 

fathoms.

Limatula,69 characterized by small, closed, virtually 

equilateral shells that have strong median ribs or interspaces, is considered generically removed from Lima. 

The modern species have a wide distribution.70 On the 

Pacific coast of America they are found from Alaska to 

Panama and the Galapagos Islands and along the coast 

of Chile. No species has heretofore been recorded from 

the California Pliocene.

Family VESICOMYACIDAE?

Genus PHREAGENA Woodring, n. gen.

Phreagena lasia Woodring, n. sp.

Plate 5, figures 3, 4

ICypricardia pedroana (Conrad) Cooper, California State Min. 

Bur. BuU. 4, p. 25 (list), 1894. Los Angeles, about 20-30 

feet below surface, Mrs. N. B. Williamson. 

Cooper (part?), in Watts, California State Min. Bur. Bull. 

11, p. 79 (list), 1897. Well on Green Meadow ranch, 

Shatto estate, West Los Angeles; Normal School, Los 

Angeles.

Dall, Wagner Inst. Sci. Philadelphia Trans., vol. 3, pt. 6, p. 

1500, 1903. "The Cypricardia pedroana of Cooper probably is a Calyptogena."

IPetricola carditoides (Conrad) Arnold (part?), in Eldridge and 

Arnold, U. S. Geol. Survey BuU. 396, p. 153 (list), 1907. 

Well on Greenmeadow ranch, Shatto estate. West Los 

Angeles; Normal School, Los Angeles; Pliocene.

ICalyptogena pacifica Dall (part), op. cit., pp. 1435-1436, 1903. 

Los Angeles; Pliocene.

Carditoid. Arnold, U. S. Nat. Mus. Proc., vol. 32, p. 527 (list), 

1907. Third Street tunnel, Los Angeles; middle Fernando formation, lower Pliocene.

Grant, in Soper and Grant, Geol. Soc. America Bull., vol. 43, 

p. 1057 (Arnold's list), 1932 [1933]. Third Street tunnel, 

Los Angeles; middle Pliocene.

M Dall, W. H., Summary of the marine shell-bearing mollusks of the northwest 

coast of America: U. S. Nat. Mus. Bull. 112, p. 20,1921.

67 Montagu, George, Testacea Britannica, supplement, p. 63, pi. 29, fig. 2, 1808 (as 

Pecteri).

w Dall, W. H., Diagnoses of new species of marine bivalve mollusks from the northwest coast of America in the collection of the United States National Museum: U. S. 

Nat. Mus. Proc., vol. 52, p. 404, 1916.

" Wood, S. V., Descriptions of the species of the genus Lima, from the Coralline 

Crag, in the cabinet of Searles Valentine Wood, Esq.: Mag. Nat. Hist., new ser., volt 

3, pp. 233, 235-236,1839 (as subgenus of Lima). Subsequently designated type (Gray, 

Zool. Soc. London Proc., 1847, p. 200), Pecten subauriculata Montagu, Recent, northeastern Atlantic.

 See Thiele, J., op. cit., pp. 38-56,1918.

Moderately large, elongate, thick-shelled. Lunule 

absent; escutcheon long, abruptly angulated and 

flattened. Sculpture consisting of strongly defined 

growth lines. Hinge of right valve consisting of a 

short, weak anterior cardinal, a heavy bifid middle 

cardinal, and a bifid posterior cardinal. Hinge of left 

valve consisting of a heavy anterior cardinal, joined to a 

heavy bifid middle cardinal, and a posterior cardinal. 

Adductor and pedal muscle scars deeply sunk. Pallial 

line apparently simple.

Length about 41.5 millimeters, height 22 millimeters 

(holotype). Length about 39 millimeters, height about 

24 millimeters.

Holotype, U. S. Nat. Mus. 496097.

This species is the type of the genus Phreagena. It 

has a hinge of venerid type, but the same structural

FIGURE 2. Hinge of Phreagena, Calyptogena, and Ectenagena. a, Phreagena lasia, 

U. S. Nat. Mus. 496097; 6, Calyptogena pacifica, U. S. Nat. Mus. 222323; c, Ectenagena 

elongata, U. S. Nat. Mus. 205888.

elements modified and arranged differently appear to 

be recognizable in the genus Calyptogena Dall. 71 Calyptogena was placed in the family Carditidae by Dall. 

Its hinge seems to be vesicomyacid and it is assigned to 

the family Vesicomyacidae. In Calyptogena pacifica 

the right anterior cardinal is thin, virtually parallels the 

margin of the valve, and is joined to the anterior part 

of the broad bifid posterior cardinal; the middle cardinal 

lies under the anterior cardinal and almost parallels 

the margin of the hinge plate. The left anterior cardinal joins the broad bifid middle cardinal and makes a 

right angle with it; the posterior cardinal is long and 

slender. (See fig. 2.) The hinge of Phreagena might 

be converted into that of Calyptogena by rotation of the 

anterior and middle cardinals, by shortening of the 

middle cardinals, and by elongation of the posterior 

cardinals. These two genera are similar in texture, 

sculpture, escutcheon, ligament area, and insertion of 

pedal muscle. Calyptogena lacks a pallial sinus, and 

Phreagena apparently has none. The hinge of Calyptogena pacifica resembles that of Vesicomya lepta

71 Dall, W. H., On some new or interesting west American shells obtained from the 

dredgings of the U. S. Fish Commission steamer Albatross in 1888, and from other 

sources [Albatross Rept.]: U. S. Nat. Mus. Proc., vol. 14, pp. 189-190, 1891. Monotype, Calyptogena pacifica Dall, Recent, Alaska.
51

(Dall),72 dredged off Oregon at a depth of 786 fathoms 

and in the Gulf of California at depths of 857 and 1,005 

fathoms. In other species from the Pacific coast 

assigned to Vesicomya, all from deep water, further 

hinge modifications are apparent. Though it is not 

certain that Vesicomya lepta and other species from the 

Pacific coast represent Vesicomya 73 proper, they probably are allied to it.

Calyptogena elongata Dall,74 from depths of 270 fathoms off Santa Rosa Island and 183 and 275 fathoms off 

Point Loma, is the only other Recent species that has 

been assigned to Calyptogena. It has a thinner and 

more elongate shell than pacifica; the right anterior 

cardinal is suppressed, the middle cardinal swings up 

to the umbo, and the posterior cardinal is shorter and 

narrower than in pacifica; the left anterior cardinal is 

not so strongly joined to the middle one and is not 

parallel to the margin of the valve, and the posterior 

cardinal is short. In many respects the hinge of 

elongata resembles that of lasia, aside from the suppression of the right anterior cardinal. The generic 

name Ectenagena is proposed for Calyptogena elongata.

Phreagena may possibly be related to the larger 

Peruvian Oligocene shells assigned by Olsson 7fi to the 

genus Pleurophopsis Van Winkle. 76 The hinge of the 

Peruvian shells is not known. The fossils associated 

with the Peruvian Pleurophopsis include Solemya and 

species assigned to Vesicomya. The Trinidad Pleurophopsis was described as having two cardinals in each 

valve. The peculiar fauna that includes Pleurophopsis 

has been recognized by Olsson in Peru, Ecuador, 

Colombia, and Trinidad.

Phreagena lasia is represented by material from the 

Third Street tunnel and from wells in the Montebello 

and West Coyote fields, near the north edge of the basin, 

but much of it is imperfect and in a poor state of preservation. Three imperfect valves and doubtful fragments 

from the Inglewood field are assigned to the Pico 

formation. An umbonal fragment of a small left valve 

from the Third Street tunnel has a hinge like the left 

valve of the holotype. The gaping valves of the holotype are held together by a remnant of the ligament. 

The shell has a thickness of about 1.7 millimeters.

» Dall, W. H., Diagnoses of new species of mollusks from the west coast of America: 

U. 8. Nat. Mus. Proc., vol. 18, pp. 17-18, 1895 [1896] (as Catlocardia). Dall, W. H., 

The M'ollusca and the Brachiopoda [Albatross Kept.]: Harvard College Mus. Comp. 

Zoology Bull., vol. 43, p. 416, pi. 18, figs. 13, 14, 1908.

" Dall, W. H., Report on the Molhisca, pt. I, Brachiopoda and Pelecypoda [Blake 

Kept.]: Harvard College Mus. Comp. Zoology Bull., vol. 12, pp. 272-273,1886 (as 

subgenus of Callocardia). Originally designated type, Callocardia atlantica Smith 

[Callocardiaf atlantica Smith], Recent, eastern Atlantic and West Indies in deep 

water.

H Dall, W. H., Diagnoses of new species of marine bivalve mollusks from the northwest coast of America in the collection of the United States National Museum: U. S. 

Nat. Mus. Proc., vol. 52, p. 408,1916; Summary of the marine shell-bearing mollusks 

'of the northwest coast of America: U. S. Nat. Mus. Bull. 112, p. 32, pi. 3, fig. 3,1921.

" Olsson, A. A., Contributions to the Tertiary paleontology of northern Peru, pt. 4, 

The Peruvian Oligocono: Bull. Am. Paleontology, vol. 17, no. 63, pp. 43-44, pi. 4, 

flgs. 1, 2, 4, 5, 7, 9, 1931.

" Van Winkle, Katherine, Remarks on some new species from Trinidad: Idem, 

vol. 8, no. 33, pp. 23-25, pi. 3, flgs. 12-14, 1919. Monotype, Pleurophopsis uninoides 

Van Winkle, probably middle Tertiary [Oligocene, fide Olsson], Trinidad.

Molds of paired valves with some shell attached in old 

collections from Los Angeles probably represent this 

species, including specimens received from J. G. Cooper 

and Mrs. M. B. Williamson in 1893. A search through 

Ball's letters from Cooper and Mrs. Williamson covering the period 1891 to 1893 fails to reveal any information about these fossils. The Cooper and Williamson 

lots are labeled Cypricardia pedroana Conrad. They 

show no trace of a pallial sinus and therefore are not 

Petricola pedroana (Conrad), which was based on a 

Pleistocene fossil from San Pedro and is considered a 

synonym of P. carditoides (Conrad).

Calyptogena pacifica is recorded by Grant and Gale 77 

as a Pliocene fossil blown out of a well in the Salt Lake 

field in Los Angeles. C. gibbera Crickmay 78 was described from the early Pleistocene silt on Deadman 

Island (Arnold's Pliocene; Alex dark's Timms Point 

formation) and was compared with pacifica. The 

hinge was not described and apparently was inaccessible.

The thick shell of C. pacijica belies its depth range. 

The type lot, consisting of 4.2 shells (still paired or 

corresponding valves) and an extra left valve, was 

dredged at a depth of 322 fathoms in Clarence Strait, 

Alaska; a paired shell is from a depth of 506 to 680 

fathoms off Santa Cruz; and a pair of corroded valves 

from a depth of 30 to 41 fathoms off Santa Rosa Island. 

The probable depth significance of Phreagena lasia is 

unknown, as its living counterpart has not been found.

Dall 79 claimed that the gills of Vesicomya stearnsii 

are foliobranch or at least intermediate between foliobranch and eulamellibranch, but Ridewood 80 found 

them to be eulamellibranch. The anatomy of Calyptogena and Ectenegena is unknown.

Specimens of Phreagena lasia from Repetto formation examined

Locality

Third Street tunnel, Los Ang

:les; Homer Hamlin. U. S. 

. S. locality 3426.

Los Angeles; J. G. Cooper. 

U. S. Nat. Mus. 115368. 

[Repetto formation (?).]

Los Angeles: Mrs. N. B. 

Williamson. . U. S. Nat. 

Mus. 115367. [Repetto formation (?).]

Sixth and Lucas Streets, Los 

Angeles, altitude 370 feet: 

R. E. C. Sterns. U. S. G. 

S. locality 2483. [Repetto 

formation (?).]

Specimens

4 imperfect paired specimens 

(3 gaping),5 imperfect valves 

(1 of which is figured) and 

fragments, including umbonal part of a small left valve 

that shows the hinge; a high 

(deformed?) right valve 

(identification doubtful).

3 paired molds, 2 of which have 

some shell attached (identification doubtful).

2 paired molds; some inner 

shell attached (identification 

doubtful).

3 paired molds, 1 of which has 

some inner shell attached 

(identification doubtful).

» Grant, U. S., IV, and Gale, H. R., op. cit., p. 279.

« Crickmay, C. H., On a new pelecypod, Calyptogena gibbera: Canadian FieldNaturalist, vol. 43, p. 93, 1 fig., 1929.

" Dall, W. H., Report on Mollusca and Brachiopoda dredged in deep water, chiefly 

near the Hawaiian Islands, with illustrations of hitherto unflgured species from 

northwest America: U. S. Nat. Mus. Proc., vol. 17, pp. 696-697, fig. 1 (p. 693), 1895 

(as Callocardia).

w Ridewood, W. G., On the structure of the gills of the Lamellibranchia: Roy. 

Soc. London Philos. Trans., ser. B, vol. 195, pp. 224-226, 1903.
LOWE& PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Specimens of Phreagena losia from Repetto formation examined 

Continued

Locality

Standard Oil Co. Baldwin No.

73, Montebello field, depth

3,340-3,358 feet. U. S. G.

S. locality 13864.

Standard Oil Co. Baldwin No.

77, Montebello field, depth

4,500 feet. U. S. G. S.

locality 13867.

Standard Oil Co. Temple No.

18, Montebello field, depth

3,044 feet. U. S. G. S.

locality 13868.

Standard Oil Co. Temple No.

19, Montebello field, depth

4,811-4,825 feet. U. S. G.

S. locality 13869a.

Standard Oil Co. Emery No.

54, West Coyote field, depth

5,900 feet. U. S. G. S.

locality 13880a.

Specimens

An imperfect paired gaping

specimen exposed in interior

view (figured holotype); 2

imperfect paired specimens.

2 imperfect paired specimens;

ligament preserved.

Imperfect left valve.

Doubtful fragments.

Incomplete left valve (identification doubtful).

Specimens of Phreagena lasia from other horizons examined

Locality

Standard Oil Co. Los Angeles

Investment No. 71, Inglewood field, depth 1,323-

1,324 feet. U. S. G. S.

locality 13891. Pico fornaa-

. tion.

Specimens

3 imperfect valves and doubtful fragments.

Family VESICOMYACIDAE

Genus CALYPTOGENA Ball

Calyptogena n. sp.

Plate 5, figures 5, 6

An incomplete, thick-shelled, short left valve, on 

which the umbonal part is corroded, from Standard Oil 

Co. Emery No. 54, West Coyote field, depth 4,230 feet 

(U. S. G. S. locality 13880), is identified as a new species 

of Calyptogena. It is less elongate than C. pacifica and 

has stronger sculpture consisting of low concentric 

lamellae. The escutcheon is abruptly angulated and 

flattened, as in pacifica. Part of the ligament is 

preserved. The hinge is imperfect but resembles the 

hinge of pacifica, as the anterior cardinal parallels the 

margin of the valve and forms a right angle with the 

bifid middle cardinal, and a wide socket lies between 

the middle and posterior cardinals. Both the anterior 

and posterior cardinals are closer to the dorsal edge 

of the hinge plate than in pacifica. An imperfect left 

valve, doubtfully determined as Phreagena lasia, was 

recovered at a lower horizon in the same well at a depth 

of 5,900 feet.

This species has the outline of Vesicomya ovalis 

(Dall) . 81 Perhaps an imperfect left valve from Standard

81 Dall, W. H., Diagnoses of new species of mollusks from the west coast of America: 

U. S. Nat. Mus. Proc., vol. 18, p. 18, 1895 (1896) (as Callocardia); The Mollusca and 

the Brachiopoda [Albatross Kept.]: Harvard College Mus. Comp. Zoology Bull., 

vol. 43, p. 417, 1908.

Oil Co. Temple No. 19, Montebello field, depth 4,811 

to 4,825 feet (U. S. G. S. locality 13869a), associated 

with Phreagena lasia, represents the same form. It 

has stronger sculpture than the specimen from the 

Emery well, and the hinge is not exposed.

Family IUCINIDAE

Genus LTICINOMA Dall

Lucinoma aff. L. aequizonata (Stearns)

Plate 5, figures 1, 2

An incomplete small right valve (height 20 millimeters) in the collection from the Third Street tunnel 

represents a Lucinoma. characterized by a strongly 

truncated posterior margin (pi. 5, fig. 1). In view of 

its outline it is improbable that this is the specimen 

identified by Arnold 82 as "Astarte species"; no specimen 

comparable to Astarte is now in the collection. The 

specimen from the Third Street tunnel appears to 

represent the same species as a moderately large right 

valve from a horizon in the East Coyote field assigned 

to the Miocene (Graham & Loftus Oil Co. No. 1, 

depth 5,957 to 5,980 feet, U. S. G. S. locality 13872a). 

The core specimen has the relatively elongate outline, 

strongly depressed posterior area and correspondingly 

strong posterior truncation, and heavy primary lamellae of the modern aequizonata (pi. 5, fig. 2). It has a 

length of 43.7 millimeters and a height of 41.5 millimeters. Parts of the outer shell layer and at places 

the entire shell are missing.

The genus Lucinoma,^ characterized by suppressed or 

weak lateral teeth and strong lamellar sculpture, is 

represented on the Pacific coast in beds assigned to the 

Oligocene and is now found from Alaska southward to 

California and in deep water to Lower California and 

along the coast of Chile. Lucina acutilineata Conrad,84 

from the Miocene of Astoria, Oreg., was the first species 

to be described from the Pacific coast. The type 

material is in the National Museum (no. 3519). The 

specimen shown in figure 2, said to be natural size, is 

not recognized. A paired specimen having most of the 

shell on the left valve and part of the shell on the right 

one, evidently the specimen shown in figures 2a, 2b, is 

designated the lectotype (length 36.8 millimeters, height 

33.9 millimeters). Two other specimens now under this 

number are molds of paired specimens. The holotype 

of Pectunculus patulus Conrad 85 (no. 3605) was recog82 Arnold, Ralph, New and characteristic species of fossil mollusks from the oilbearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 32, 

p. 527 (list), 1907. Arnold, Ralph, in Eldridge, G. H., and Arnold, Ralph, The Santa 

Clara Valley, Puente Hills, and Los Angeles oil districts, southern California: U. S. 

Geol. Survey Bull. 309, p. 152 (list), 1907.

83 Dall, W. H., Synopsis of the Lucinacea and of the American species: U. S. Nat. 

Mus. Proc., vol. 23, p. 806, 1901 (as subgenus of Phacoides). Originally designated 

type Lucina filosa Simpson, Recent, Maine to Florida.

14 Conrad, T. A., in Dana, 3. D., Geology, U.S. Expl. Exped., p. 725, pi. 18, figs. 

2, 2a, 2b, 1849.

« Idem, p. 726, pi. 18, figs. 8, 8a.
MOLLUSKS 53

nized as a mold of acutilineata by Meek. 88 The impression of the elongate anterior muscle scar is clearly 

visible on the mold; the puckers near the lower anterior 

margin are too strong on the drawing. A specimen of 

acutilineata somewhat larger than the lectotype (length 

47.4 millimeters, height 42.8 millimeters) has been 

figured from the Miocene of southern Washington,87 

and this species has been recognized in the Miocene 

Vaqueros 88 and Temblor 89 formations of California. 

It has been pointed out that the type of acutilineata 

has a shorter posterior dorsal margin than the modern 

annulata This difference also holds for the Miocene 

specimen from the Coalinga region figured by Arnold, 

but other specimens from the same locality (4803, 

Coalinga anticline) have a longer posterior dorsal margin 

than the one figured. Miocene representatives so far 

figured are relatively small; an incomplete one from 

locality 4860 (Wagonwheel Mountain, Devil's Den 

district) has a'length of about 57 millimeters. The 

range of variation in outline and size of the Miocene 

Lucinoma has not yet been determined, and the hinge 

is still unknown. L. annulata (Reeve) 91 attains a 

length of 70 millimeters and a height of 64 millimeters 

in Puget Sound and surrounding waters. Shells from 

Alaska are considerably smaller, and those from 

California, dredged at depths of 10 to 414 fathoms, are 

smaller still. Small shells from California resemble the 

figure published by Reeve, who cited the locality as 

"California?". A large shell labeled "San Pedro" 

(U. S. Nat. Mus. 151726), which has some sand matrix 

adhering to it, evidently is a fossil from the lower 

Pleistocene San Pedro sand; it agrees with fossils collected from that formation on Deadman Island (locality 

12530). L. annulata densilirata Dall,92 based on a pair 

of valves from Sitka, Alaska, is larger than other 

Alaskan specimens and has a more steeply sloping 

posterior dorsal margin and more closely and more 

irregularly spo,ced primary lamellae. A relatively wellpreserved shell from the Jacalitos formation (locality 

4644), fossils from Elsmere Canyon (locality 4401) 

where Lucinoma is abundant, and a flattened left valve 

from Ring Oil Co. More No. 1, .near Goleta, Santa 

Barbara County, depth 4,957 feet, received from 

W. S. W. Kew, resemble modern shells. Most specimens from the Etchegoin formation (localities 4664,

" Meek, F. B., Chock list of the invertebrate fossils of North America; Miocene: 

Smithsonlan Misc. Coll., no. 183, p. 29,1864. Meek erroneously cited Lucina acutilineata as Lucina occidentalis.

" Etherington, T. J., Stratigraphy and fauna of the Astoria Miocene of southwest 

Washington: California Univ., Dept. Qeol. Sci., Bull., vol. 20, pp. 76-77, pi. 4, fig. 5, 

1931 [as Phacoides (Lucinoma)}.

18 Loci, Wayne, and Corey, W. H., The Vaqueros formation, lower Miocene of 

California, 1, Paleontology: Idem, vol. 22, p. 211, pi. 36, fig. 3, 1932 [as Phacoides 

(.Lucinoma)].

« Arnold, Ralph, Paleontology of the Coalinga district, California: U. S. Geol. 

Survey Bull. 396, p. 17 (list), pi. 8, flg. 4,1909 [1910] (as Phacoides, Vaqueros formation).

50 Stpwart, R. B., in Togland, N. M., The fauna of the type Blakeley upper Oligocono of Washington: California Univ., Dept. Oeol. Sci., Bull., vol. 23, p. 116,1933.

 ' Reeve, L. A., Conchologica iconica; Lucina, species 17, pi. 4, flg. 17, 1850 (as 

Lucina).

' Dall, W. H., New shells from the northwest coast: BjoJ. Soc, Washington Proc., 

vol. 32, p. 249,1919.

White Creek syncline; 12817, Kettleman Hills) have 

a strongly concave anterior dorsal margin. Phacoides 

columbianum Clark and Arnold,93 from the Sooke 

formation of Vancouver Island, considered of Oligocene 

age by Clark, belongs in the acutilineata-annulata 

group. It was described as having an anterior lateral; 

the figures closely resemble the Miocene acutilineata.

L. aeguizonata 94 has been dredged at depths of 183 

to 405 fathoms from the Channel Islands southward 

to Lower California. It has an elongate shell, strongly 

depressed posterior area and correspondingly strong 

posterior truncation, and relatively strong laterals. 

Adult shells are corroded in the umbonal region. The 

posterior truncation of Phacoides hannibali Clark,95 

from the Washington Oligocene, suggests that it is 

allied to aeguizonata, but not all the specimens figured 

by Tegland are strongly truncated. The presence of 

a species of the aeguizonata group in the Miocene at 

Astoria is indicated by material from locality 5318 

(northwest corner of 10th Street and Harrison Avenue). 

L. heroica (Dall),98 known only from a lot of fine shells 

dredged off Lower California at a depth of 1,005 

fathoms, has strongly sloping dorsal margins. The 

Chilean L. lamellata (Smith) 97 has a long anterior 

end, which, however, is not well developed on some 

young shells. The pair of young valves from Chile, 

listed by Dall 98 under aeguizonata, apparently represent lamellata. °

Family CARDIIDAE

Genus TRACHYCARDIUM Mbrch

Subgenus DALLOCARDIA Stewart

Trachycardium (Dallocardia) cf. T. quadragenarium (Conrad)

Plate 9, figure 1

The collection from the Third Street tunnel contains 

a small fragment of the lower part of the right valve of 

a large thick-shelled Trachycardium not mentioned by 

Arnold. According to the curvature of the ribs it 

represents the region lying in front of the middle of 

the shell. The shell has a thickness of about 7 millimeters. The ribs are more or less eroded. Where the 

ornamentation is preserved it consists of heavy oblique 

ridges extending from the posterior edge of a rib forward 

to or beyond the middle. In the corresponding region 

large Recent specimens of guadragenarium have broadbased blunt spines, the base of which extends forward

ra Clark, B. L., and Arnold, Ralph, Fauna of the Sooke formation, Vancouver 

Island: California Univ., Dept. Oeol. Sci., Bull., vol. 14, pp. 144-145, pi. 25, figs. 

2a, 2b, 1923. Clark, B. L., Pelecypoda from the marine Oligocene of western North 

America: Idem, vol. 15, p. 89, pi. 22, flg. 9, 1925.

 < Stearns, R. E. C., Descriptions of new west American land, fresh-water, and 

marine shells, with notes and comments [Albatross Rept.]: U. S. Nat. Mus. Proc., 

vol. 13, pp. 220-221, pi. 17, figs. 3, 4, 1890.(as Lucina).

» Clark, B. L., op. cit., p. 89, pi. 22, figs. 2, 4,1925. Tegland, N. M., op. cit., pp. 

115-116, pi. 8, figs. 5-13.

«« Dall, W. H., U. S. Nat. Mus. Proc., vol. 23, pp. 812, 828, pi. 41, flg. 1,1901.

" Smith, E. A., Mollusca and Molluscoidea [Alert Rept.]: Zool. Soc. London 

Proc., 1881, pp. 38-39, pi. 5, figs. 1-lc (as Diplodonta).

" Dall, W. H., Summary of the marine shell-bearing mollusks of the northwest 

coast of America: U. S. Nat. Mus. Bull. 112, p. 35,1921.
54 LOWER PLIOCENE MOLLTJSKS AND ECHINOIDS FROM LOS ANGELES BASIN

not farther than about the middle of a rib. With the 

proper amount of wear the spines of guadragenarium 

probably would be converted into ornamentation like 

that seen on the fossil.

Arnold described as Cardium quadrigenarium [error 

for guadragenarium] Conrad var. Jernandoensis a form 

from the Pliocene of Elsmere Canyon," differentiated 

by being smaller, more oblique, and less inflated and 

by having a narrower umbo and fewer (36 as against 

more than 40) and less spinose ribs. In addition to the 

type two imperfect specimens are represented in the 

collection from Elsmere Canyon (locality 4401). The 

type and the one other specimen that shows the outline 

are more elongate than young Recent shells of guadragenarium. The difference in inflation and in the width 

of the umbones appears to be negligible. The character 

of the ornamentation depends on the amount of wear; 

where it is preserved it resembles that of Recent shells. 

The type is the only specimen on which the number of 

ribs is discernible. There appear to be 37 or 38, the 

number depending on what is included at the ends of 

the shell. On four modern shells of comparable size 

the count is 41 to 45. This may be a recognizable 

variety or subspecies, but more material is desirable. 

It was recognized by English * at Elsmere Canyon 

and Pico Canyon. Cardium guadragenarium has been 

identified in formations as old as the upper Miocene 

San Pablo 2 and is now found along the coast from 

Santa Barbara to Lower California. It is the type of 

Dallocardia,3 proposed as a subgenus of Trachycardium.4

Family VENERIDAE

Genus KATHERINELLA Tegland

Subgenus COMPSOMYAX Stewart

Katherinella (Compsomyax) aff. K. subdiaphana (Carpenter)

Plate 6, figure 12

Several imperfect valves from Chanslor-Canfield 

Midway Oil Co. Torrance No. 71, Torrance field, depth 

3,245 feet (U. S. G. S. locality 13915), appear to be 

similar to the modern "dementia" subdiaphana Carpenter 5 and to the Miocene Oregon "Venus" angustifrons Conrad.6 The most nearly complete specimen,

98 Arnold, Ralph, New and characteristic species of fossil mollusks from the oilbearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 

32, p. 535, pi. 48, figs. 2, 2a, 1907.

iEnglish, W. A., The Fernando group near Newhall, Calif.: California Univ., 

Dept. Geology, Bull., vol. 8, p. 209,1914.

1 Clark, B. L., Fauna of the San Pablo group of middle California: Idem, vol. 8, 

p. 417,1915 (as quadrigenarium).

1 Stewart, R. B., Qabb's California Cretaceous and Tertiary type lamellibranchs: 

Acad. Nat. Sci. Philadelphia Special Pub. 3, p. 264, 1930. Originally designated 

type, Cardium quadrigenarium Conrad [error for quadragenarium].

* Morch, 0. A. L., Yoldi catalog, pt. 2, p. 34, 1853. Subsequently designated type 

(Von Martens, Zool. Record, 1869, p. 586,1870), Cardium iaocardia Linne, Recent, 

West Indies.

1 Carpenter, P. P., Supplementary report on the present state of our knowledge 

with regard to the Mollusca of the west coast of America: British Assoc. Adv. Sci. 

Rept. for 1863, pp. 602, 640, 1864; Diagnoses specierum et varietatum novaram molluscorum, prope Slnum Pugetianum a Kennerlio Doctore, nuper decesso, collectorum: 

Acad. Nat. Sci. Philadelphia Proc., 1865, p. 56 (as ?dementia).

«Conrad, T. A., in Dana, J. D., Geology, U. S. Expl. Exped., p. 724, pi. 17, fig. 11, 

1849.

which has a restored length of about 33 millimeters and 

a height of 28 millimeters and probably is flattened, is 

figured. An attempt was made to expose the hinge of 

this specimen. The middle cardinal was broken off at 

the base, and the distal part of the anterior cardinal also 

was damaged. The posterior cardinal is not so deeply 

bifid as in fresh modern specimens of subdiaphana. 

This apparent difference is probably a matter of wear, 

as in one worn right valve dredged off Oregon at a 

depth of 61 fathoms (U. S. Nat. Mus. 210964) the 

posterior cardinal is not more deeply bifid. K. subdiaphana ranges from Alaska to San Pedro, Calif. 

Two small corresponding valves (length 18.5 millimeters, height 15 millimeters) in the National Museum 

collected by Kennerly in Puget Sound are labeled 

"types" (no. 4541). As the dimensions do not agree 

exactly with those given by Carpenter, this pair of 

valves is considered the lectotype. A small, badly 

broken left valve under the same number, also collected 

in Puget Sound by Kennerly, may have been the one 

measured by Carpenter. Large specimens from localities between Alaska and northern California attain a 

length of 58 millimeters and a height of 46.9 millimeters. 

No large shells are in the National Museum from localities south of Drakes Bay, Calif. Shells dredged off 

the Channel Islands are small or of medium size and 

relatively short.

The relations of subdiaphana to the Miocene angustifrons are still unknown, but the two forms appear to be 

closely allied, and the Recent one may eventually take 

the name angustifrons. The specimen figured by Conrad may be one of two under National Museum no. 

3492, but the posterior part is higher than shown in 

the figure, and only a small part of the outer shell is 

preserved; at all events this specimen is taken as the 

lectotype. Ten other specimens, some of which were 

labeled "Marcia oregonensis" by Dall, are in the Dana 

Astoria collection. In outline and sculpture many of 

these specimens resemble short shells of subdiaphana. 

The hinge of the Miocene fossil has not yet been described. Dall 7 considered angustifrons the same as 

Cytherea oregonensis Conrad,8 also described from 

Astoria. A Miocene species from southern Washington 

that appears to. agree reasonably well with Conrad's 

figure has been identified as oregonensis and assigned to 

"Pitaria." g Dall's Marcia oregonensis (Conrad) 10 from 

the Pliocene of Coos Bay, Oregon, closely resembles in 

outline the modern subdiaphana, with which he compared it. The holotype of "Venus" brevilineata Conrad,11 a paired mold, is under no. 3606. It has a short

7 Dall, W. H., The Miocene of Astoria and Coos Bay, Oregon: U. S. Geol. Survey 

Prof. Paper 59, p. 123, 1909.

8 Conrad, T. A., Fossil shells from Tertiary deposits on the Columbia River, near 

Astoria: Am. Jour. Sci., 2d ser., vol. 5, p. 432, fig. 8, 1848.

» Etherington, T. J., Stratigraphy and fauna of the Astoria Miocene of southwest 

Washington: California Univ., Dept. Geol. Sci., Bull., vol. 20, pp. '78-79, pi. 6, figs. 

1-3, 1931.

10 Dall, W. H., op. cit. (Prof. Paper 59), pp. 123-124, pi. 2, fig. 12, pi. 11, fig. 9, pi. 12. 

fig. 3, 1909.

» Conrad, T. A., op. cit. (U. S. Expl. Exped.), p. 724, pi. 17, fig. 13,1849.
MOLLUSKS 55

anterior end and appears to be a variety of angustifrons, 

as treated by Etherington. 12 It is not clear what 

Etherington meant in differentiating angustifrons from 

subdiaphana by "the absence of the sunken area just 

anterior to the beak" in angustifrons. K. subdiaphana 

is found in the Pliocene of Elsmere Canyon and Holser 

Canyon 13 and is recorded from Los Angeles.14

Compsomyax 15 is considered a subgenus of Katherinella, 10 which apparently is its predecessor. According 

to Tegland's figures, Katherinella has a weak anterior 

lateral that is absent in Compsomyax, and the right 

posterior cardinal is not so strongly bifid as in Compsomyax. In outline and sculpture Compsomyax closely 

resembles Katherinella. The strong anterior lateral of 

the Recent species, said to be from Alaska, described 

by Tegland as Pitaria ida,17 indicates that it is not allied 

to Katherinella.

Genus MACROCALLISTA Meek 

Macrocallista sp.

A mold of a right valve (length about 54 millimeters, 

restored height about 34.5 millimeters), on which the 

umbonal part is missing, is identified as a Macrocallista. 16 It was obtained from Great American Petroleum Co. Tuffree No. 2, East Coyote field, at a depth 

of 3,351 to 3,356 feet (U. S. G. S. locality 13873). 

Part of the smooth shell originally adhered to the mold, 

but peeled off when the core was split. Enough of the 

hinge is preserved to reveal the anterior laterals and 

the almost vertical and closely spaced anterior and 

middle cardinals. The lower lateral, which is broken, 

appears to lie in front of and to overlap the upper one 

instead of lying directly under it. This species is more

>« Etherington, T. J., op. cit., pp. 81-82, pi. 6, figs. 6, 7 [as Marcia (Merdmonia)].

" Ashloy, Q. H., The Neocene stratigraphy of the Santa Cruz Mountains of California: California Acad. Sol. Proc., 2d ser., vol. 5, p. 238, 1895 (as Sazidomus gibbosus 

Gnbb?, ridge over San Fernando tunnel). Arnold, Ealph, New and characteristic 

species of fossil mollusks from the oil-bearing Tertiary formations of southern California: U. S. Nat. Mus. Proc., vol. 32, pp. 526 (list), 544, pi. 49, fig. 3,1907 (as Callista, 

Elsmoro Canyon). Arnold, Ralph, in Eldridge, G. H., and Arnold, Ralph, The 

Santa Clara Valley, Puonto Hills, and Los Angeles oil districts, southern California: 

U. S. Gcol. Survey Bull. 309, pp. 25 Gist), 250, pi. 39, fig. 3,1907 (as Callista, Elsmere 

Canyon). English, W. A., The Fernando group near Newhall, Calif.: California 

Univ., Dept. Geology, Bull., vol. 8, p. 210 (list), 1914 (as Marcia, Elsmere Canyon 

and Holser Canyon). Kew, W. S. W., Geology and oil resources of a part of Los 

Angeles and Vcntura Counties, Calif.: U. S. Geol. Survey Bull. 753, p. 78 (list), 1924 

(as Marcia, Elsmere Canyon, Holser Canyon, near Pico Canyon).

14 Cooper, J. G., In Watts, W. L., Oil and gas yielding formations of Los Angeles, 

Vontura, and Santa Barbara Counties: California State Min. Bur. Bull. 11, p. 80, 

1897 (as Saxidomus gibbosus Gabb; Shatto estate, West Los Angeles). Arnold, 

Ralph, in Eldrldgo, G. H., and Arnold, Ralph, op. cit, p. 153, 1907 (as Saxidomus 

gibbostts Gabb; Shatto estate, West Los Angeles).

" Stowart, R. B., Gabb's California Cretaceous and Tertiary type lamellibranchs: 

Acad. Nat. Scl. Philadelphia Special Pub. 3, p. 224,1930 (as subgenus of Venerella). 

Originally designated type, Saxidomas gibbosus Gabb (= V. subdiaphana (Carpenter), 

Pliocene to Recent, Pacific coast.

'o Tegland, N. M., Correlation and affinities of certain species of Pitaria: California 

Univ., Dopt. Geol. Scl., Bull., vol. 18, pp. 280-282,1929. Originally designated type, 

Callocallista arnoldi Weaver, Ollgocene, Washington.

» Tegland, N. M., Pitaria ida, a new Recent species from Alaska: Nautilus, vol. 

42, pp. 4-6, 1928; Correlation and affinities of certain species of Pitaria: California 

Univ., Dopt. Geol. Scl., Bull., vol. 18, pp. 283-284, pi. 22, figs. 7-10,1929.

is Meek, F. B., A report on the invertebrate Cretaceous and Tertiary fossils of the 

upper Missouri country: U. S. Geol. Survey Terr. Rept., vol. 9, p. 179, 1876. Monotype, Venus gigantea Gmelin (= Venus nimbosa Solander, fide Dall), Recent, West 

Indies.

145569 38 5

elongate than any known to be living on the Pacific 

coast and in outline seems to resemble more closely the 

Miocene to Recent West Indian M. maculata (Linn6). 

A similar but smaller elongate Macrocallista has be'en 

recognized in the Miocene of the Palos Verdes Hills. 19

Family CORBULIDAE

Genus CORBULA Bruguiere

Subgenus VARICORBULA Grant and Gale

Corbula (Varicorbula) gibbiformis Grant and Gale

Plate 6, figures 8, 9

Corbula (Corbula) gibbiformis Grant and Gale, San Diego Soc. 

Nat. History Mem., vol. 1, pp. 420-421, pi. 19, figs. 4-6, 

1931. Type from well in San Joaquin Valley (Southern 

California Gas Co. No. 1-4, sec. 4, T. 28 S., R. 23 E., 

depth 3,951 to 3,952 feet); upper Etchegoin formation 

[San Joaquin formation?], upper Pliocene.

A relatively large Varicorbula with a short posterior 

rostrum. Right valve sculptured with strong concentric undulations; left valve sculptured with at least 12 

radial riblets which, except at the ends of the shell, are 

arranged in pairs or triplets.

Length 11.3 millimeters, height (not quite complete) 9.8 millimeters, diameter (both valves) 8.3 

millimeters.

A paired, not quite complete specimen from Great 

American Petroleum Co. Tuffree No. 2, East Coyote 

field, depth 3,351 to 3,356 feet (U. S. G. S. locality 

13873), associated with Macrocallista sp., is assigned to 

Corbula gibbiformis. According to Grant and Gale's 

figures, the right valve is a little smaller and more 

elongate than the holotype of gibbiformis but is not 

more elongate than a paratype from the same core 

(fig. 4);.and the left valve has more numerous radial 

riblets than the paratype of gibbiformis, but this apparent difference may be a matter of preservation. With 

more material it may be possible to differentiate the 

coastal form from the San Joaquin Valley form. In 

addition to the type locality, Grant and Gale recorded 

gibbiformis from the Pecten coalingaenis zone, now 

assigned to the San Joaquin formation, of the Kettleman Hills in San Joaquin Valley, and in association 

with Acila semirostrata from a locality near Camulos, 

in the Ventura Basin, that they assigned to the middle 

Pliocene. Two poorly preserved worn right valves, 

collected by Ralph Stewart from gravel in the Pecten 

coalingaensis zone on the west side of the northern 

Middle Dome of the Kettleman Hills (locality 12384), 

are larger and less elongate than the specimen from the 

Los Angeles Basin.

Varicorbula is not represented in the collection of 

Recent mollusks from the west coast of America in the

» Woodring, W. P., in Woodring. W. P., Bramlette, M. N., and Kleinpell, R. M., 

Miocene stratigraphy and paleontology of Palos Verdes Hills, California: Am. ASSOCJ 

Petroleum Geologists Bull., vol. 20, p. 138 (list, Macrocallista cf. M. maculata (Linnfi)), 

1936.
56

National Museum, and no species are recorded from 

the Miocene of the west coast of North America. It is 

represented in the Peruvian Miocene 20 and is widespread in the Miocene of the West Indian region, where 

it is now represented by C. disparilis D'Orbigny,21 but 

is not known earlier than the lower Miocene in this 

region and Florida. The status of Corbula binominata 

Hanna,22 from the upper Pliocene of Los Angeles, is 

uncertain.

The nomenclature of the subdivisions of Corbula 25 

has recently been discussed by Gardner,24 Stewaft,25 

and Grant and Gale. 26 If Schmidt's designation of C. 

sulcata is accepted, the provisionally proposed Varicorbula 27 appears to be the name to use for American 

and European Corbulas with dissimilarly sculptured 

valves. Perhaps this name will be supplanted by 

Notocorbula Iredale,28 proposed for an Australian 

species that has a long rostrum and is said to have a 

keeled cardinal tooth. Iredale claimed that specific 

names were first assigned to Corbula in the Museum 

Boltenianum.29 As there are no citations to Bruguiere's 

figures and as it has not been shown that any of the 

valid species are the same as Bruguiere's unnamed ones, 

the Corbula of this publication is considered a homonym 

of Corbula Bruguiere, a conclusion reached by Stewart.

Family PERIPLOMIDAE 

Genus PERIPLOMA Schumacher

Periploma cryphia Woodring, n. sp.

Plate 9, figures 4, 6

A short, slightly elongate, thin-shelled Periploma of 

medium size. Posterior end rounded. Sculpture over 

greater part of shell consisting of regular fine concentric 

undulations that disappear toward ventral and posterior 

margins. Chondrophore buttress thin and long.

2° Spieker, E. M., The paleontology of the Zorritos formation of the north Peruvian 

oil fields: Johns Hopkins Univ. Studies in^Geology, no. 3, pp. 170-172, 1922 (as 

Aloidis). Olsson, A. A., Contributions to the Tertiary paleontology of northern 

Peru, pt. 5, The Peruvian Miocene: Bull. Am. Paleontology, vol. 19, no. 68, p. 135, 

1932 (as undesignated subgenus).

21 See Woodring, W. P., Miocene mollusks from Bowden, Jamaica, Pelecypods 

and scaphopods: Carnegie Inst. Washington Pub. 366, pp. 188-189,1925 (as Corbula 

s. s.).

" Hanna, Q. D., Rectifications of nomenclature: California Acad. Sci. Proc., 4th 

ser., vol. 13, p. 163,1924. New name for Corbula tennis Moody, 1916 (California Univ., 

Dept. Geology, Bull., vol. 10, p. 59, pi. 2, figs. 4a, 4b): not Sowerby, 1833.

23 Bruguiere, J. G., Tableau encyclop6dique et mfethodique, Vers testacfies, vol. 2, 

pi. 230, 1797 (genus without named species). Subsequently designated type 

(Schmidt, Versuch * * der Conchylien-Sammlungen, p. 77,1818, fide Stewart), 

Corbula sulcata Lamarck, Recent, West Africa.

24 Gardner, Julia, The nomenclature of the superspecific groups of Corbula in the 

lower Miocene of Florida: Nautilus, vol. 40, pp. 41-47, 1926; The molluscan fauna of 

the Alum Bluff group of Florida: U. S. Geol. Survey Prof. Paper 142-E, pp. 226- 

228, 1928.

" Stewart, R. B., Gabb's California Cretaceous and Tertiary type lamellibranchs: 

Acad. Nat. Sci. Philadelphia Special Pub. 3, pp. 286-287,1930.

2" Grant, U. S., IV, and Gale, H. R., op. cit., pp. 420-421.

27 Idem, p. 420, footnote. Originally designated type Corbula gibba (Olivi), Recent, 

Mediterranean.

2S Iredale, Tom, More notes on the marine Mollusca of New South Wales: Australian Mus. Rec., vol. 17, p. 404, 1930. Originally designated type, N. vicaria Iredale, 

Recent, New South Wales.

'?« Roding, P. F., in Bplten, J. F., Museum Boltenianum, pt. 2, p. 184, 1798.

Length 35.2 millimeters, height about 29.5 millimeters (holotype). Length 26.9 millimeters, height 

19.5 millimeters.

Holotype, U. S. Nat. Mus. 496104.

The holotype (pi. 9, fig. 6) is a left valve from Union 

Oil Co. Hellman No. 17, Dominguez field, depth 3,939 

,feet (U. S. G. S. locality 13898). A more elongate 

right valve (pi. 9, fig. 4) from Union Oil Co. Hellman 

No. 14, Dominguez field, depth 5,102 feet (U. S. G. S. 

locality 13897), is referred to this form. Part of the 

.outer shell layer is missing on the holotype, and the 

insertion of the long, thin chondrophore buttress shows 

through the shell. Much of the shell is missing on the 

.specimen from Hellman No. 14; the insertion of the 

buttress is visible; the umbo appears to be fissured; 

and at the posterior end> where an area of shell is 

preserved, the concentric undulations are replaced by 

: strong growth threads.

This species may be allied to one from Weaver's 

Blakeley formation of Washington (Oligocene) described as Cochlodesma bainbridgensis Clark,30 which 

according to the figures has strong concentric undulations. Whether bainbridgensis has a long, thin buttress 

is not known. Cochlodesma 31 has a broad, blunt 

buttress and a thin, low supplementary one under it; 

Dall 32 treated it as a subgenus of Periploma. P. 

cryphia is not similar to any Recent species now known 

on the Pacific coast. P. stearnsii Dall,33 a shallow-water 

species from the head of the Gulf of California, and 

P. carpenteri Dall,34 dredged at a depth of 210 fathoms 

off Panama, are somewhat similar in outline but have 

granular sculpture and a short blunt buttress. A small 

unnamed Japanese species in the collections of the 

National Museum (Suruga Gulf, 503 fathoms; Japan 

Sea, 325 fathoms) has a long, thin triangular buttress 

but lacks the strong sculpture. A deep-water species 

ranging from Nova Scotia to Chesapeake Bay (depth 

101 to 300 fathoms), labeled "P. abyssorum Verrill,. 

1893", has a similar buttress but lacks the strong sculpture. I have not discovered where this name was 

published. P. Jragilis (Totten) and P. papyratia 

(Say), two small species from the Atlantic coast, also 

have a thin buttress. Perhaps these species with a 

long, thin triangular chondrophore buttress strongly 

diverging from the umbo deserve subgeneric rank.

30 Clark, B. L., Pelecypoda from the marine Oligocene of western North America: 

California Univ., Dept. Geol. Sci., Bull., vol. 15, p. 86, pi. 13, figs. 3, 4,1925. Tegland, 

N. M., The fauna of the type Blakeley upper Oligocene of Washington: Idem, vol. 

23, p. 112, pi. 6, figs. 3, 4, 1933.

3 ' Couthouy, J. P., Monograph of the family Osteodesmacea: Boston Soc. Nat. 

History, Jour. Nat. History, vol. 2, p. 170, 1839. Monotype, Cochlodesma leana 

(Conrad) (=rAnatina leana Conrad), Recent, Atlantic coast of United States.

32 Dall, W. H., Tertiary fauna of Florida: Wagner Inst. Sci. Philadelphia Trans., 

vol. 3, pt. 6, p. 1528, 1903.

33 Dall, W. H., Diagnoses of new species of mollusks from the west coast of America: 

U. S. Nat. Mus. Proc., vol. 18, p. 19, 1895 [1896]. Dall, W. H., The Mollusca and 

theBrachiopoda.[^4i6a.fro«s Rept.]: Harvard College Mus. Comp. Zoology Bull., vol. 

43, pp. 426-427, pi. 16, fig. 5, 1908.

34 Dall, W. H., op. cit. (1895 [1896]), p. 20; pp. cit. (1908), p. 426, pi. 16, fig. 8.
ECHINOIDS 57

Periploma 35 proper has a relatively thick shell, a short 

posterior end, weak granular sculpture, and a thick, 

blunt buttress inserted parallel to the margin of the 

valve. Halistrepta*6 proposed as a subdivision of 

Periploma, is characterized by heavy undulations that 

do not conform to the growth lines and by a broad low 

buttress.

Periploma discus Stearns has been recorded from a 

Los Angeles locality (First and Olive Streets) 37 that 

may represent the Repetto formation.

Periploma cryphia stenopa Woodring, n. var.

Plate 9, figure 7

Larger and more elongate than cryphia proper and 

having a more pointed posterior end.

Length 45.2 millimeters, height 33.9 millimeters 

(holotype).

Holotype, U. S. Nat. Mus. 496106.

Inasmuch as it is improbable that the difference in 

outline is due to deformation, the large elongate left 

valve from Union Oil Co. Hellman No. 18, Dominguez 

field, depth .4,076 feet (U. S. G. S. locality 13899) is 

considered a variety of cryphia. Almost all the outer 

shell material is missing on this specimen; the umbo 

seems to be fissured; and the insertion of the long, thin 

chondrophore buttress is visible. An incomplete elongate left valve from Standard Oil Co..Baldwin No. 73, 

Montebello .field, depth 4,745 feet (U. S. G. S. locality 

13864a), probably represents this elongate Periploma. 

The upper posterior margin is slightly truncated. 

Cochlodesma bambridgensis is more similar in outline to 

this elongate form but appears to have a narrower 

posterior end.

ECHINOIDS

Family ECHINOTHURIIDAE

Genus ARAEOSOMA Mortensen

Araeosoma sp.

[Identification by Th. Mortensen] 

Plate 9, figures 2, 3

Two poorly preserved incomplete echinoids from 

Standard Oil Co. Murphy Coyote No. 117, West 

Coyote field, depth 4,400 feet (U. S. G. S. locality 

13875), were recognized by Dr. A. H. Clark, of the 

United States National Museum, as echinothuriids. 

They were examined by Dr. H. L. Clark, of the Harvard 

Museum of Comparative Zoology, who concurred in

« Schumachor, C. F., Essai d'un nouveau systeme des habitations des vers testacfis, 

pp. 115-110, 1817. Monotype, Periploma inaequivalvis Schumacher, Recent, West 

Indies.

'« Dall, W. H., A now species of Periploma from California: Nautilus, vol. 17, pp. 

122-123, 1904. Originally designated type, Periploma sulcala Dall, Recent, California.

17 Coopor, J. G., in Watts, W. L., Oil and gas yielding formations of Los Angeles, 

Ventura, and Santa Barbara Counties: California State Min. Bur. Bull. 11, p. 80 

(list), 1897. Arnold, Ralph, in Eldridge, Q. H., and Arnold, Ralph, op. cit. (Bull. 

309), p. 153 (list), 1907.

this identification, and on his recommendation were 

forwarded to Dr. Th. Mortensen, of the Zoological 

Museum of the University of Copenhagen. Dr. Mortensen identified them as an undeterminable species of 

Araeosoma, probably more closely allied to the West 

Indian A. fenestratum (Thomson) and A. belli Mortensen than to the eastern Pacific A. eurypatum A. Agassiz 

and H. L. Clark and A. leptaleum A. Agassiz and H. L. 

Clark, but stated that the material is too incomplete 

to be certain of the affinities.

One specimen (pi. 9, fig. 2) consists of part of the 

inner side of the oral surface with the lantern in place 

and includes an ambulacrum and interambulacrum, 

half of another interambulacrum, and part of another 

ambulacrum. The distance from the center to the 

edge, which may be some distance from the ambitus, 

is 25.5 to 33.5 millimeters. The interambulacrum has 

a width at the distal edge of 24.5 millimeters, the half 

ambulacrum 15.7 millimeters; and the ambulacrum 

about 19 millimeters. The pores are not clearly discernible. The interambulacra have an adradial series 

of primary tubercles, usually one on each plate, an 

admedian series, and a few scattered tubercles between 

the two series toward the ambitus. The ambulacra 

have an admedian series. The preserved part of the 

peristome shows numerous narrow imbricating plates. 

The other specimen (pi. 9, fig. 2) from the same core 

consists of part of the aboral surface telescoped onto 

the inner side of the oral surface, which has the lantern 

in place. The outer edge at the place of maximum 

diameter appears to be the ambitus, indicating a horizontal diameter of 82 millimeters. Only the greater 

part of an aboral ambulacrum and interambulacrum 

in exterior view and the peristome, seen from the inside, 

are clearly shown. The incomplete interambulacrum 

has a maximum width of 23 millimeters. The interambulacral adradial series of tubercles adjoining the 

preserved ambulacrum appear to be present only near 

the ambitus.

These specimens, incomplete as they are, are of 

exceptional interest, inasmuch as they are the first 

fossil representatives of the family Echinothuriidae to 

be found in America and apparently the first Tertiary 

specimens from any region represented by more than 

isolated spines. The Echinothuriidae have recently 

been monographed by Mortensen,38 who recognized 13 

Recent species of Araeosoma. No echinothuriids have 

been dredged along the California coast. The Albatross 

dredged A. eurypatum A. Agassiz and H. L. Clark 39 off 

the Galapagos Islands at a depth of 671 fathoms and 

A. leptaleum A. Agassiz and H. L. Clark 40 off Panama at 

a depth of 581 fathoms.

.38 Mortensen, Th., A monograph of the Echinoidea, II, pp. 80-292, pis. 1-65, 74-83, 

Copenhagen, 1935.

" Agassiz, A., and Clark, H. L., Hawaiian and other Pacific Echini: Harvard 

College Mus. Comp. Zoology Mem., vol. 34, pp. 181-183, pi. 66, flgs. 18,19; pis. 73-75, 

1909.

«Idem, pp. 183-185, pis. 76, 77.
58 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN

Numerous slender spines, represented principally by 

vertical sections in which the structure is obscure, are 

in a core from Standard Oil Co. Bastanchury Ranch 

No. 1, West Coyote field, depth 6,414 feet (U. S. G. S. 

locality 13884). They have a length of about 4 to 7 

millimeters and a diameter of about 0.1 to 0.2 millimeter. Those that show the exterior have fine roughened ribs. A few show the enlarged base, which has a 

diameter of about 0.3 millimeter and a length of about 

0.35 millimeter. Horizontal sections showing the same 

diameter probably represent the base. One spine 

shown in vertical section terminates in a swelling that 

has a length of 0.7 millimeter and widens near the end 

to a diameter of 0.35 millimeter. These may be spines 

of an echinothuriid. According to Mortensen's illustrations, they are relatively small for primary spines 

and none clearly show the characteristic hoof. Part of 

a test probably was in this core, but the substance

now present is too powdery to make out any plates. 

An imperfect imprint of a curled leaf is in the 

same core.

The occurrence of another echinoid in the Repetto 

formation is indicated by poorly preserved material, 

too imperfect for identification. A mold (length about 

73 millimeters, height about 39 millimeters) of almost 

half an echinoid, collected by W. H. Holman, of the 

Standard Oil Co. of California, on the north side of 

Wilshire Boulevard 200 feet east of the center line of 

Bixel Street (U. S. G. S. locality 13923), is identified by 

A. H. Clark as a cassidulid. Fragments from a horizon 

in the Huntington Beach field assigned to the Miocene 

(Standard Oil Co. Pacific Electric No. 15, depth 3,174 

to 3,180 feet, U. S. G. S. locality 13903) are considered 

by Clark as a spatangid, possibly one of the Hemiasteridae. A few strongly ribbed spines are associated 

with these fragments.
PLATES 5-9

59

M55fi9 3S 0
PLATE 5

[Figures natural size unless otherwise designated]

FIGURE 1. Lucinoma aff. L. aequizonata (Stearns). Small incomplete right valve. Height 20 millimeters. Third Street tunnel, 

Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496331.

2. Lucinoma aff. L. aequizonata (Stearns). Right valve.' Length 43.7 millimeters, height 41.5 millimeters. Graham & 

Loftus Oil Co. No. 1, East Coyote field, depth 5,957 to 5,980 feet; U. S. G. S. locality 13872a. Miocene. U. S. Nat. 

Mus. 496100.

3. Phreagena lasia Woodring, n. gen., n. sp. Holotype; gaping valves held together by remnant of ligament. Length about 

41.5 milimeters, height 22 millimeters. Standard Oil Co. Baldwin No. 73, Montebello field, depth 3,340 to 3,358 feet; 

U. S. G. S. locality 13864. U. S. Nat. Mus. 496097.

4. Phreagena lasia Woodring, n. gen., n. sp. Imperfect right valve. Length (incomplete) 40 millimeters, height (incomplete) 25.5 millimeters. Third Street tunnel, Los Angeles; 0. S. G. S. locality 3426. U. S. Nat. Mus. 496098. 

5, 6. Calyptogena n. sp. Exterior and hinge of imperfect left valve. Length (incomplete) 26.5 millimeters. Standard Oil 

Co. Emery No. 54, West Coyote field, depth 4,230 feet; U. S. G. S. locality 13880. U. S. Nat. Mus. 496099.

7. 12. Limopsis (Felicia} phrear Woodring, n. sp. Hinge and exterior of paratype, an elongate left valve. Length 20.5 millimeters, height 14.7 millimeters. Union Oil Co. Callender No. 27, Dominguez field, depth 4,998 feet; U. S. G. S. 

locality 13896. U. S. Nat. Mus. 496078.

8. 13. Limopsis (Felicia) phrear Woodring, n. sp. Hinge and exterior of short (deformed?) left valve. Length 18.4 millimeters, 

height 21.5 millimeters. Pacific Western Oil Corporation Cone No. 16, Tnglewood field, depth 2,926 to 2,945- feet; 

U. S. G. S. locality 13892. U. S. Nat. Mus. 496079.

9. Limopsis (Felicia) phrear Woodring, n. sp. Left valve of holotype, an elongate gaping paired shell. Length 17.8 millimeters, height 15.4 millimeters. Shell Oil Co. Reyes No. 101, Dominguez field, depth 5,245 feet; U. S. G. S. locality 

13900. U. S. Nat. Mus. 496077.

10, 11. Acila (Acila) semiroslrala (Grant and Gale). Flattened right valve (fig. 10) and impression (fig. 11). Length 22 millimeters, height 18.5 millimeters. Wilmington Terminal Oil Co. Banning No. 1, Wilmington field, depth 3,265 feet; 

U. S. G. S. locality 13916. U. S. Nat. Mus. 496071.

14. Solemya (Acharax) aff. S. johnsoni Dall. Right valve of imperfect paired shell. Length (incomplete) 30.8 millimeters, 

height 15.8 millimeters. Standard Oil Co. Baldwin No. 73, Montebello field, depth 3,340 to 3,358 feet; U. S. G. S. 

locality 13864. U. S. Nat. Mus. 496070.

15. Buccinum? sp. Rear view of imperfect crushed specimen. Length (incomplete) 42.8 millimeters, width (crushed) 

25.6 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496069.

16. "Nassa" hamlini Arnold, X 2. Side view of imperfect specimen. Length (incomplete) 13.8 millimeters, width (crushed) 

6 millimeters. Standard Oil Co. Emery No. 52, West Coyote field, depth 3,695 feet; U. S. G. S. locality 13878d. J. S. 

Nat. Mus. 496067.

17. Astraea (Pomaulax) cf. A. gradala Grant and Gale. Rear view of imperfect deformed specimen. Length (incomplete) 

65.5 millimeters, greatest width (exaggerated by compression) 90.5 millimeters. Third Street tunnel, Los Angeles; 

U. S. G. S. locality 3426. U. S. Nat. Mus. 496061.

18. Plicifusus? sp. Rear view of imperfect deformed specimen. Length (incomplete) 47.2 millimeters, width (crushed) 29.9 

millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496068.

19. Lunatia cf. L. caurina (Gould), X 2. Length 8.4 millimeters, width 6.8 millimeters. Standard Oil Co. Baldwin-Cienega 

No. 105, Inglewood field, depth 2,221 feet; U. S. G. S. locality 13890. U. S. Nat. Mus. 496062.

20. Acila? (Truncacila?-) cf. A. castrensis (Hinds). Right valve; outer shell layer missing. Length 13 millimeters, height 

9.7 millimeters. Union Oil Co. Farwell No. 17, Santa Fe Springs field, depth 5,631 feet; U. S. G. S. locality 13885. 

U. S. Nat. Mus. 496072.

21. Fusitriton aff. F. oregonensis (Redfield). Incomplete specimen having exceptionally subdued ribs. Length (incomplete) 

about 70 millimeters, width (crushed) 37.5 millimeters. Union Oil Co. Callender No. 22, Dominguez field, depth 

4,146 feet; U. S. G. S.. locality 13895. U. S. Nat. Mus. 496066.

22. Fusitriton aff. F. oregonensis (Redfield). Incomplete specimen having strong, relatively widely spaced ribs. Length 

(incomplete) 53 millimeters, width (crushed) 44 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 

3426. U. S. Nat. Mus. 496065.

23. Fusitriton aff. F. oregonensis (Redfield). Incomplete specimen having subdued, closely spaced ribs. Length (incomplete) 

77 millimeters, width (crushed) 66.5 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. 

Nat. Mus. 496064. 

60
iOLOGICAL SURVEY PROFESSIONAL PAPER 190 PLATE 5

21

PLIOCENE AND MIOCENE MOLLUSKS FROM LOS ANGELES BASIN.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 190 PLATE 6

14

I'UOCENE AND MIOCENE MOLLUSKS FROM LOS ANGELES BASIN.
PLATE 6

[Figures natural size unless otherwise designated]

Hyalopecten (Delectopecten) cf. H. pedroanus (Trask). Faintly sculptured left valve. Length 30.5 millimeters, height 26.7 

millimeters. St. Helen's Petroleum Co. P. & B. No. 6, Montebello field, depth 5,704 feet; U. S. G. S. locality 13870. 

From a horizon close to contact between Miocene and Pliocene. U. S. Nat. Mus. 4960S2.

2. Hyalopecten (Delectopecten) cf. H. pedroanus (Trask). Strongly sculptured left valve. Length 17 millimeters, height 

about 17 millimeters. Graham & Loftus Oil Co. No. 1, East Coyote field, depth 5,592 to 5,615 feet; U. S. G. S. locality 

13872. Miocene. U. S. Nat. Mus. 496083.

3. Hyalopecten (Delectopecten) aff. H. randolphi lillamookensis (Arnold), X 2. Interior of left valve of medium size; part of 

shell missing. Length 12.5 millimeters, height about 12 millimeters. Julian Oil Co. Farnsworth No. 2, Huntington 

Beach field, depth 2,081 feet; U. S. G. S. locality 13908. U. S. Nat. Mus. 496085.

4. Hyalopecten (Delectopecten) aff. H. randolphi tillamookensis (Arnold), X 10. Interior view of part of valve of medium size, 

showing sculpture. Standard Oil Co. Vickers No. 1 lease, well 27, Inglewood field, depth 1,240 to 1,253 feet; U. S. G. S. 

locality 13SSS. Pico formation. U. S. Nat. Mus. 496084.

5. Hyalopecten (Delectopecten) afT. H. randolphi (Dall). Large left valve; concentric undulations moderately strong; most 

of shell material missing except on anterior ear. Length 34.5 millimeters, height 33.5 millimeters. Southern California Drilling Co. Matteson No. 1, near El Segundo, depth 2,081 feet; U. S. G. S. locality 13912. Pico formation. 

U. S. Nat. Mus. 4960S6.

6. Hyalopecten (Delectopecten) aff. H. randolphi (Dall). Upper part: Right valve; concentric undulations weak; shell missing 

except inner layer on ears and nearby. Length about 27 millimeters, height 28.7 millimeters. Lower part: Impression 

of incomplete right valve; concentric undulations weak; shell preserved in interior view on part of anterior ear, showing 

sculpture of anterior ear. Southern California Drilling Co. Matteson No. 1, near El Segundo, depth 2,081 feet; U. S. 0. S. 

locality 13912. Pico formation. U. S. Nat. Mus. 496087.

7. Hyalopecten (Delectopecten) afT. H. randolphi (Dall). Impression of incomplete left valve; concentric undulations strong; 

some shell material preserved. Length (incomplete) 22.2 millimeters, height 26.2 millimeters. Standard Oil Co. Baldwin-. 

No. 4.1, Montebello field, depth 3,600 feet; U. S. G. S. locality 13907. U. S. Nat. Mus. 496328.

8, 9. Corbula (Varicorbula) gibbiformis Grant and Gale, X 2. Right (fig. S) and left (fig. 9) valves of paired shell. Length 11.3 

millimeters, height (not quite complete) 9.8 millimeters. Great American Petroleum Co. Tuffree No. 2, East Coyote 

field, depth 3,351 to 3,356 feet; U. S. G. S. locality 13873. U. S. Nat. Mus. 496103.

10, 13. Anadara camuloensis (Osmont). Anterior end (fig. 10) and exterior (fig. 13) of imperfect worn right valve. Length 

(incomplete) 78.5 millimeters, height (incomplete) 72.5 millimeters. A. T. Jergins Trust Robertson No. 1, Playa del 

Rey field, depth 3,830 feet; U. S. G. S. locality 13911. U. S. Nat. Mus. 496076.

11. Hyalopecten (Delectopecten) aff. H. randolphi (Dall), X 10. Impression showing camptonectes sculpture. Anterior part of 

specimen shown in lower part of figure 6.

12. Katherinella (Compsomyax) aff. K. subdiaphana (Carpenter). Imperfect right valve. Length (incomplete) 31 millimeters, 

height 28 millimeters. Chanslor-Canfield Midway Oil Co. Torrance No. 71, Torrance field, depth 3,245 feet; U. S. G. S. 

locality 13915. U. S. Nat. Mus. 496102.

14-16. Anadara camuloensis (Osmont). Anterior end (fig. 14), interior (fig. 15), and exterior (fig. 16) of imperfect worn right 

valve. Length (incomplete) 69.5 millimeters, height (not quite complete) 75.5 millimeters, diameter about 45 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496075.

61
PLATE 7

[Figures natural size]

FIGURE ]. Lyropeclen cerrosensis (Gabb). Four fragments mounted on plaster of paris model in form of a complete valve. Third

Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496081.

2. Lyropecten cerrosensis (Gabb). Imperfect left valve. Length (incomplete) 100 millimeters, height 117 millimeters, length 

of cardinal margin about 60 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 

496080. 

62
GEOLOGICAL SURVEY PROFESSIONAL PAPER 190 PLATE 7

\

PLIOCENE MOLLUSKS FROM LOS ANGELES BASIN
GEOLOGICAL SURVEY PROFESSIONAL PAPER 190 PLATE 8

11

PLIOCENE MOLLUSKS FROM LOS ANGELES BASIN AND MIOCENE MOLLUSKS FROM COLORADO DESERT
PLATE 8

[Figures natural size unless otherwise designated]

1, 2. Ostrea vcsperlina Conrad. Weakly plicate right valve from type region. Barrett's oil well [on south side of Carrizo 

Creek], Imperial County, Calif.; U. S. G. S. locality 3921. Imperial formation, Miocene. Length 42.8 millimeters, 

height 49.7 millimeters. U. S. Nat. Mus. 496329.

3. S. Ostrea vespcrtina Conrad. Lectotype, an incomplete right valve. Length (incomplete) 37.7 millimeters, height 48.6 

millimeters. "Near San Diego" [evidently Carrizo Creek]. Acad. Nat. Sci., Philadelphia, 13366.

4. 9. Ostrea vcspertina Conrad. Strongly plicate right valve from type region. Barrett's oil well [on south side of Carrizo 

Creek], .Imperial County, Calif.; U. S. G. S. locality 3921. Imperial formation, Miocene. Length 46.6 millimeters, 

height 53.3 millimeters. U. S. Nat. Mus. 496330.

5. Lima (Acesta} hamlini Da.ll. Left valve of medium size having smooth central area; lower part of shell missing. Length 

58.5 millimeters, height 75 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. 

Mus. 496093.

6. Limalula afT. L. "subauriculala (Montagu)", X 4. Shell partly missing. Height 7.6 millimeters, length 4.4 millimeters. 

Universal Consolidated Oil Co. Nutt. No. 2, Montebello field, depth 3,627 to 3,655 feet; U. S. G. S. locality 13871. 

U. S. Nat. Mus. 496096.

7. Lima (Acesta} hamlini Dall. Small left valve having smooth central area; large part of shell missing. Length 46 

millimeters, height 56.5 millimeters. Third Street tunnel, Los Angeles; U, S. G. S. locality 3426. U. S. Nat. Mus. 

' 496094.

10. Lima (Acesta} hamlini Dall. Large, almost complete, crushed right valve having subdued sculpture in central area*. 

Length 82 millimeters, height 90 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. 

Nat. Mus. 496092.

11. Lima (Acesta) hamlini Dall. Large crushed right valve having smooth central area; most of shell missing. Length 

70.5 millimeters, height 85.5 millimeters. Standard Oil Co. Murphy Coyote No. 117, West Coyote field, depth 

5,910 feet; U. S. G. S. locality 13S75a. U. S. Nat. Mus. 496095.

63
PLATE 9

[Figures natural size unless otherwise designated]

FIGURE 1. Tr achy car din m (Dallocardia) cf. T. quadragenarium (Conrad). Fragment from lower anterior-median part of large right 

valve. Length 47.5 millimeters. Third Street tunnel, Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496101.

2. Araeosoma sp., X 2. Part of inner side of oral surface; lantern in .place. Distance from center to edge 25.5 to 33.5 millimeters. Standard Oil Co. Murphy Coyote No. 117, West Coyote field, depth 4,400-feet; U. S. G. S. locality 13875. 

U. S. Nat. Mus. 496107.

3. Araeosoma sp., X 2. Part of abofal surface telescoped onto inner side of oral surface, which has lantern in place. Maximum distance from center to edge 41 millimeters. Standard Oil Co. Murphy Coyote No. 117, West Coyote field, 

depth 4,400 feet; U. S. G. S. locality 13875. U. S. Nat. Mus. 496108.

4. Pcriploma cryphia Woodring, n. sp. Elongate right valve; most of shell missing. Length 26.9 millimeters, height 19.5 

millimeters. Union Oil Co. Hellman No. 14,. Dominguez field, depth 5,102 feet; U. S. G. S. locality 13897. U. S. 

Nat. Mus. 496105.

5. Osirea vespertina Conrad. Imperfect, elongate, strongly plicate left valve. Height 66.6 millimeters. Third Street tunnel, 

Los Angeles; U. S. G. S. locality 3426. U. S. Nat. Mus. 496089.

6. Periploma cryphia Woodring, n. sp. Holotype, left valve; part of outer shell missing. Length 35.2 millimeters, height 

about 29.5 millimeters. Union Oil Co. Hellman No. 17, Dominguez field, depth 3,939 feet; U. S. G. S. locality 13S98. 

U. S. Nat. Mus. 496104.

7. Periploma cryphia stenopa Woodring, n. var. Holotype, left valve; part of outer shell missing. Length 45.2 millimeters, 

height 33.9 millimeters. Union Oil Co. Hellman No. 18, Dominguez field, depth 4,076 feet; U. S. G. S. locality 13899. 

[J. S. Nat. Mus. 496106. 

64
GEOLOGICAL SUEVEY PROFESSIONAL PAPER 190 PLATE

6 7

PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN.
INDEX

Abstract.

Page 

l

Accsta.......................... ............................................. 47-49

Acharax....................................................................... 27-28

Acilu.......................-..........--.--.....-.-....--.-...-.-.--.-.----.. 28-29

(Acila) somirostrata..........................................-..-.. 20, 28, pi. 5

(?) (Truncacila?) cf. A. castrensis.................................... 29, pi. 5

Acknowledgments for aid_.................................................. 1-2

ucosmitn, Euspira............................................................ 22

acutilinoata, Lucina.......................................................... 52-53

Aequipecton circularis deserti ........................................... 45

aequizonata, Lucinoma att.............................................. 52-53, pi. 5

agassizii, Liina............................................................... 48

agassizi, Solomya............................................................. 27

Aloctrion gonioplcura ...................................................... 26

Alotos? cf. A. squauilgorus.___ ................~............................ 20

altornilinoatus, Pocten (Pseudamusiuin) ................................... 38

Anudara.....................-------------------------...---.-.---.---------.- 29-31

cumulocnsis.-...............-......-.--.----.--..-.---------.--.--. 29-31, pi. 6

iiuil'ticostattt..---.--------------------------------------------------- 30

a(T. A. multicostata....................................................... 21

aft'. A. trillneata.......................................................... 20

nngelonsis, Prlene oregonensis var.-.........-.------.---------.---------.--.. 23

Solonosteira............................-..-.-.-.---.----.--------.-.--.-. 21

angustlfrons, Venus..-......................--.-...-...--...-.-..-.....-.---. 54,55

amuilata, Lucinoma..................-.....----.......---.......-..-.....---. 53

amuilatus, Plagiostoina....................................................... 37

Anoiiilasubcostata..-....................------------------------------------ 45

Araoosoma................................................................... 57-58

oury patuin............................................................. 57

lop talcum --............................-.--.-..--.-.--..-----.--..-.. 67

sp.................................................................. 57-58, pi. 9

Area.....................................--.---..-.-----.---...-----.--------- 30

canalis ..................

grandis.....-...............:

in icrodon ta.................

trl lineata...................

arcos, Pocten (Pseudamuslum)-

...... -..---..... --.-....- . 31

......................................... 30

..-.-..-.......-..-.-....--......----.- 31

.......-.....-......---...-----.-------.. 31

......................................... 37

Arcldao.........................--.... ..--.......... ......... . 29-31

A rgobuccinu m............................................................... 24

scotlaonsis.........................:....-............---..--.....-...-.... 24

Astartosp........--......--...-.....-..----------.-.-..----------.----.-.---- 52

Astraoa..-........--..._..--.-..--..-------.-.-------------------------------. 22

broaonsis..............-................--..--.-..-----..-----..---------. 22

turbauica.................--.............----.-.--.-------------.--.--- 22

(Pomaulax) cf. A. gradata........................................ 20,22, pi. 5

attcnuata, Limatula.......................................................... 50

B 

balnbridgonsis, Cochlodosma...---.-------......--------.---.------------.---56,57

Bartsch, Paul, acknowledgments to.....................................--....---.2

binominata, Corbula......................................................... 56

breaonsis, Astraea........................................................ 22

CaiHIiariis--..--,----------------------------------.---------------------- 21

brovilinoata, "Venus"........................................................ 54-55

Brown, R. W., acknowledgments to_........................................ 2

Buccinidae?...........!...................................................... 26-27

Bucclnutn viridum........................................................... 26

(?) sp.........................................-......-------------. 26-27, pi. 5

California, relief map of, showing principal areas of marine Pliocene formations, pi. l 

californiana, "Nassa" cf....................................................... 20

californionsls, Mancalla....................................................... 6,11

Callithaca aft'. 0. tenerrima................................................... 20

Callolima................. __..._......................_._..................... 48

Calyptogona............................................................... 50-51,52

olongata......_.._.....___..._._._._.....__._._.-.._....-.--._...-._-...__ 51

glbbera.........__....................................._._.-...:.-..-.._ 51

paciftca...............___._..._....._-..---.-...-.-.-......--..-....... 50-51,52

Calyptogona n. sp......................................................... 52, pi. 5

Calyptraea a(t. C. iHnniillaris..............----..--..--..--------.--.-......-. 20

alt. 0. radians............................................................ 20

Page 

camuloensis, Anadara............................ ...................... 29-31, pi. 6

canalis, Area __ ............................................................. 31

"Cancellaria" hernphilli... ................................................ _ 20

cancellatum, Triton .......................................................... 24

Cantharus breaensis ..-.--......_.__..____....______..__..__.........__.__._._ 21

Cardiidae _ . _ .............................................................. 53-54

carditoides, Petricola. ._..._.-..-...._.-.._._

Cardium quadrigenarium var. fernandoensis 

carpenter!, Periploma _ . _________ .... 

Cassidulid echinoid -.--..-------.-.--....-

___._..____........_..___._ 51

.----------------..----.--- 54

........................... 56

.--........................ 58

castrensis, Acila? (Truncacila?) cf............................ .............. 29, pi. 5

catalinae, Lyropecten estrellanus var _ ....................................... 34

caurina, Lunatia cf_ _ .. __ . _ ..-....-..-.-...-.-...............-...-. 22-23, pi. 5

centifilosa, "Protocardia" cf _ ........................................... __ 20

cerrosensis, Lyropecten... ................... ........................ 21, 32-35, pi. 7

Chione cf. C. fernandoensis.-----.----.--.-.--.----.------.-..---.-.-..--....- 20

Chlamys aff. C. etchegoini _ ................................................ 21

Clark, A. H., acknowledgments to _ ........................................ 2

Clark, Alex, acknowledgments to..-....---..-.---.-..--...-.---.-...-...--.-- 2

Cochlodesma. .--.-...----..-...................--....-.......-...-.......-.-- 56

bainbridgensis. . ......-.--------.---------..----..-..-.-.--._--.-._--.-..- 56, 57

columbianum, Phacoides. .................................................... 53

compressus, Limopsis. ........................................................ 32

Compsomyax _ . ............................................................. 54-55

Continental Shelf of southern California, bathymetric map of .............. 19

Continental Shelf of southern California, deep-water basins of.--..-........-. 18

cooperi, Turritellacf.. ..................................... .................. 20

Yoldiacf ............................................................. 20

Corbula-.-.-----.--.---------------------.....-..-..-.-....-...-.---...-.-.-- 55-56

binominata- .............................................................. 56

( Varicorbula) gibbiform is. ........................................... 55-56, pi. 6

Corbulidae.. -...-..-....--.--.-.--..-.--.--.---------------------.--..-.-..-- 55-56

crassicardo, Lyropecten _ .................................................... 34

Crepidulacf. C. onyx.........-...-----.----.-....----..--................-... 20

Cryotritonium.... . ........................................................... 24

cryphia, Periploma.. ._.....-..__._____..._____.__._.____.._.___.__..____ 56-57, pi. 9

Cymatiidae -------------------.-------------------------------------.---- 23-25

Cy pricardia pedroana --.--.-----.-.-..-........-..........................-.. 51

C y therea oregonensis. ......................................................... 54

D 

dalli, Limopsis- ____ .... _ ................................................ 32

Solemya _ ............................................................... 28

Dallocardia..---.-'.--..-..-.-.........-......---.-..-.............--........-- 53-54

De Laubenfels, M. W., acknowledgments to _ .............................. 2

Delectopecten _-..._ ________ .......................................... 35-42

densata, Mulinia. ----.-..----......-..--..........................-..---..-.. 31

densilirata, Lucinoma annulata _ ............................................ 53

deserti, Aequipecten circularis................................................ 45

Diluvarca.. ____ --.-.-......-....-.-...-.-...-........-.........-.....--.- 31

discus, Periploma...................

Donax? protexta....................

Driver, H. L., acknowledgments to.

E

Echinoids.-.-..----------...--.-..-----------------.-----------------.-- 57-58,pi.9

Echinothuriidae........................................................__-- 57-58

Ectenagena...---..-............--.---......-...--.-..-.--....--.-..-...._.. 51

elongata.................................................................. 50

elongata, Calyptogena........................................................ 51

Ectenagena_............................................................ 50

estrellanus, Lyropecten...............:....................................... 33-34

etchegoini, Chlamys aff....................................................... 21

eurypatum, Araeosoma....................................................... 57

Euspira...................................................................... 23

acosmita_............................................................... 22

Felicia....................................................................... 31-32

fernandoensis, Cardium quadragenariuni var................................. 54

Chione cf................_.....__..................................... 20

Pecten (Pseudamusium) vancouverensis.................................. 38,41

flsheri, Ostrea................................................................. 46

Fissuridea murina............................................................ 6

65
66 INDEX

Page 

Fusitriton___._.._--.._____.._._.____..__________________.___._.___.__________ 23-25

oregonensis---.........-..-..-...-..-..-.................-..-.--....... 21, 23-24

aff. F. oregonensis.................-..-.............................'. 23-25, pi. 5

G 

gallegosi, Pecten (Lyropecten).----.--................_.._-...._.__.__.__.i___ 34

gibbera, Calyptogena...___............................................... 51

gibbiformis, Corbula (Varicorbula)...................--.-....---.---..... 55-56,pi. 6

Gigantopecten................................................................. 35

goniopleura, Alecttion.______________________.____..____._.____._____.._..._._ 26

goniostoma, Turritella cf...__----.-..---.--......-.....-.--..-.............. 20

gradata, Astraea (Pomaulax) cf......----..-................-.--...... 20, 22, pi. 5

grandis, Area................................................................. 30

H 

Halistrepta...__ ----------____......................._._......_ 57

hamlini, Lima (Acesta)----._--------__...-__....................... 47-49, pi. 8

"Nassa".....-....-..-.-.---.-.--.--.----............---..----.-. 20,25-26, pi. 5

"Radiolites"__....-..-.--..-...---.-........-..--..---.-...--.-.-.-.... 6

Uca....................................................................... 6,11

hannibali, Phacoides.....----...-.-----

heermanni, Ostrea.................-...-

hemphilli, ''Cancellaria"...'....-..-....

heroica, Lucinoma......................

Hertlein, L. O., acknowledgments to.-- 

Hoffrneister, J. E., acknowledgments to. 

Holman, W. H., fossils collected by__ 

Hughes, D. D., acknowledgments to_ 

humerosa, "Neptunea"? cf._.........

.. . -:. _ .-.-. 53 

.---_-----_-.---------..------. 46

................................ 20

........... ... ......... 53

..------.--------------.---..--. 2

.--..-------.-.-----.-.---.-.--- 2

................................. 2

..___.___-.__-____.___._.___._. 2

...............^................. 20

Hyalopecten.................................................................. 35-42

lillisi....... ......... .... . ........ ....-...-...... 40

peckhami_.--.-....................--.................'.................. 39-40

pedroanus---_.___..._------------__...._...._........___. 38-39

cf. H. pedroanus......................-......_............ ............. 41, pi. 6

(Delectopecten) aff. H. randolphi ................._---------_. 35-41, pi. 6

aff. H. randolphi tillamookensis_-..-_........................... 41-42, pi. 6

ida, Pitaria................................................................... 55

Imperial formation of Colorado Desert, age of--_.-_.-._-_-----------_-___._--- 46-47

interradiatum, Propeamussium_....-.....-.--.-.----------..---............ 40

johnsoni, Solemya (Acharax), aft_..................................... 27-28, pi. 5

jousseaumi, Limopsis_........1.........................................._ 32

K 

Katherinella_...---..........------.-.-..-.......-........--.--.-......---.. 54-55

(Compsomyax) afF. K. subdiaphana............................. 20,54-55, pi. 6

Kew, W. S. W., acknowledgments to.-.--.--..-..--....-..-.-.-.---.......... 1-2

lamellata, Lucinoma. 

Larkinia_.....----.

.................................:..... ......... 53

................................................... 30

lasia, Phreagena........................L----..------------------------- 50-52, pi. 5

latiauritus, Pecten............................................................ 6,7

lepta, Vesicomya...--..........--.-..--..--............--.-..-............... 50-51

leptaleum, Araeosoma........................................................ 57

lillisi, Hyalopecten................................_.......................... 40

Pecten (Pseudamusium)_.............................................. 38

Lirna.-...__------__..._.......-. ..-.-.-.-----....--.-.-.--....--...- 47^19

agassizi...................................................-............_... 48

(Acesta) hamlini-.._......................................_..... 47-49, pi. 8

(Plagiostoma) oregonensis..........-..............-.---...--..-......-.-. 48

Limatula____-------_....-..-.--.--.-.-......-....--...-..--.-......._ 49-50

a ttenuata_.............................................................. 50

all. L. "subauriculata"..---..-.------------_-----------.-.--_----- 49-60, pi. 8

Limidae...--__-_.-.-.._.--_---..------------__------------------------.---- 47-50

Limopsidae ................................r ............................... 31-32

Limopsls..-.-.--....-..-....-.-..--....--.-.-.--..---.-----.-.-..-.--...-.- 31-32

compressus....................... ....- ... .-..---. --.-.. ...... .. 32

dalli.............. .. .-.. . .-.... ...... 32

jousseaumi--..---.__......... .. ........ - .. ..-.-- -..- 32

zonalis.-._.___..... ........- -...-._. . -.--.- . . 32

(Felicia) phrear...___ ..... . ....__... ..... .......... 31-32, pi. 5

Lopha__ _-_- _.. - - -- - _--- -- 46

Los Angeles Basin, comparison of, during Repetto time with modern deapwater basins on Continental Shelf of southern California......---- 18

general features of__.._____...-.-----.-----------.--.-----_------------- 2-3

generalized geologic map of---...-.--------------------------------------- pi. 2

map of, showing distribution of Repetto fossils of different depth facies... pi. 4 

Lucina acutilineata...__...-...--.-.---..-.------.'-.._..------...-.--.---- 52-53

Lucinidae.- ----..---------. ------------------..--------------------------- 52-53

Page 

Lucinoma-.---------.----.................................................... 62-53

annulata__.-.-..--....-.-..-..-....-.-. -.......-.-.--.--..-.--....... 53

densilirata......-- .......................................... ......._ 53

heroica................................................................... 53

lamellata................................................................. 53

aff. L. aequizonata__.............................................. 52-53,pi. 5

Lunatia..._--..__........................................................ 22-23

cf. L. caurina_..--................. ............................... 22-23, pi. 5

lurida, Ostrea__.--..-...................-..---............----..-.--....... 44

Lyropecten_--.-.. ............--.......-. ............................. 32-35

cerrosensis_. .- .... .. ....... .... . .. .. 21,32-35, pi. 7

crassicardo_.....----.........................._......................... 34

estrellanus__-.-.---......-.....-.-.--.----.....-.-.- -..--.--.......... 33-34

var. catalinae........_.. ......................................... 34

var. terminus._...-_.-.--..............................._........ 34

M

Macrocallista.

sp.

----.-...-_._..-_---------....-..-------....-..--....--. 55

... ......-.....-..-.-................-................. 55

mamillaris, Calyptraeaaff....................................-.-....----....... 20

Mancalla californiensis...-----............................................... 6,11

Marcia oregonensis......-.............------.---.................--.--....... 54

microdon ta, Area............................................................. 31

Miocene of Los Angeles Basin, subsurface, larger fossils from..-.---.-..--..... 17

Mollusks............................................................. 22-57, pis. 5-9

Morrison, J. P. E., acknowledgments to.-.-.--............................... 2

Mortensen, Th., acknowledgments to__.----.----------------.-------.--.-. 2

Mulinia densata_..__..._....--------.---.--..--------------.-----.-...- 31

multicostata, Anadara........................................................ 30

Anadara aff....___................................................... 21

murina, Fissuridea..-_.................................................__ 6

''Nassa" ..__..._.....__...._........................__......... 25-26

hamlini.--..._.---.-.............-..-------.....-.----.--..--..-- 20, 25-26, pi. 5

to wnsendi................................................................. 25

cf. "N." californiana_......................................._........... 20

Nassarius__-..-.---._ ......................'.............................. 26

"Nassidae"_....-..-.--......-.........-..-----........-.....-...-....._.. 25-26

Naticidae___..........____ ...1......................................... 22-23

"Neptunea"? cf. '.'N. " humerosa....-----------------------------------..--.. 20

Neptuneidae?._----------.......------------------.---_.----------..--.-.-... 26

Neverita aff. N. reclusiana_................................................ 20

New systematic names proposed.--------------------------------------------- 2

Nodipecten_-_.............i............................................... 35

Notocorbula. -.-.-.-.----..............-..-..-...----...-.--...-..-.-.--....-. 56

Nuculidae------------.---...-_-------.------------------------------------..- 28-29

0 

onyx, Crepidula cf ..- . --....--..---.--.-------.--.-..-.-..-.----.-.----....- 20

opuntia, Pecten.............................................................. 0

oregonensis, Cytherea._...................................................... 54

Fusitriton............-_-_._.......__--_--.--.....-.._.--..--.-.--.-... 21,23-24

Fusitriton aft.._..__............................................. 23-25.pl. 5

Lima (Plagiostoma)...................................................... 48

Marcia. -.-..--.-.-..---.-.-------.---.---..-.-.---.--.--..-..-.-----....- 54

Ostrea..-.-----------.----.-------------.-.------.----.---.-------------------- 42-47

fished...-- 

heermanni. 

lurida.... .

--........-.--...-....-..--.-.....-.-.-.....----..-...... 46

-------.---------------------.---.-----------------.----. 46

-.-.-.--.-.--.-...-.---.-_--.----.-.--..-------.----.-..- 44

palmula.............................-.-..---........----.-..-...-...---.- 44-45

veatchii...--.-.......-............-.--..-.-.-..--.-..-..-..-_-....-...... 45

vespertina...............---..:.---.--- ---------------------- 21,42-47, pis. 8,9

var. sequens.-.-................-..-.--._..----...-..-....------.----- 44

Ostreidae...-.--------------.-_------------.---------------------------------- 42-47

ovalis, Vesicomya----.... ---.--.............................------.--...-..-. 52

pacifica, Calyptogena...--...--.------------------.---.---------.--.------- 50-51, 52

Palliolum ...___._.....-..-.-...-. .....-.--....-...--..--------..-.- 40

palmula, Ostrea...--......---....-.-....-- -------....-..-....-----------.--- 44-45

Palos Verdes Hills, outcrops of Repetto formation in......,__._.._.. _.._.. 4

patulus, Pectunculus...-------..------------.-.--.---.---------.--------.---- 52-53

peckhami, Hyalopecten.-....-.................--..........-.----.--.-.--.-..- 39-40

Pecten. ....................1...........^............................... 37

Pecteu latiauri tus -_ --_- -.-- ----. --.--- - ---- -- ----- - 6, 7

opuntia__..........-.....-.-.--.--.--..---...--..--..-.-.---..--.-...-.. 6

peckhami__...-..--......-.-....----..--..---...-..-..-... .-..----.-.-- 37

randolphi__.......................--.-.-.-..-.------....--.---..-.-...- 37

stearnsii-. -- -----.- - --- ------- ----- ------- 0

vanwinkleae.. - -------.....------..------------.-.----------.-.-.----.--.- 40

(Delectopecten) zacae__.............-..---........-...--------------.-. 38

(Lyropecten) gallegosi...............---.--.--..--.-..--...--..-.--..-..-.- 34
INDEX 67

Pecten (I'soudamusium) al tern ilincatus.............'...._..-------------..-.

(Pseiidamusium) arees_-- .....-..-..--...--.--.....--------. -.

lillisl . - - . . ------ ---.

pol ylep Mis..---.----------------------------------..---------------.

randolphi vnr. tillaiiiuokensis.--------------------------------------

vancouveronsis-----------------------------------------------------

forimudoeiisis--.._--.---..---.----------..---.-------------------- 38,41

sniijiumciisis...... --------------------------------------------- 38

......-....-----------.-.-.---.-------------------------------- 32-42

Page 

38

37

38

37

37

37

Peclinidno ------------------------------------------------------------

PecUmeuliis patuIns.....-----------------------------------------------

pedroana, Cypricardia..------------------------------------------------

Petricola. ..........................................................

Plagiostonm........-..-.------------------------.-._--.---------.--

pedroanus, Ilyulopcctcii-..--------------------------------------------

1:1 yalupcctcn cf-. .----.-------.---------------------------------------41

Poriploiiw.-..--..---.__....------------------.-----..--------------.---------

onrpen tcri................-.----.-.......------..-..-..--------_-----------

cryphia........__......_....-....-.-.-................---.--.--- 56-57,

StCllOpa..._..-----..------------._-------------.----------------------

Peri ploma discus..----_.......--.............---.-....-..-.-.----.--...---.-.

stoarnsii.---.-------------------------------------------------------------

Peri plomidae.-.--.----..--.-----------.-------.--------------------.-------..

Petricola cardi toidcs.....-.....-..---....-_----...-.._._...-.---.......--..-.-

pcdroana.___...._._._..._._-.-.-_.......-_.-.-.--._......---.----.....--.

Plmcoidcs Columbian inn....-.--..--.-.---...---....----.--.--------...-......

hiuinibiili..... --_.--..-----------------------------------------.----------

P11 reagena............__....__.....__...__....___.____..__._..______.___..__..

lasiii........................-.-.--..--..--.-.-..-.----.---...-.---... 50-52,

|.>lircnr, Limopsis (Felicia).............................................. 31-32,

Pico formation, larger fossils from........_._..._._.._.__..._....._____________

Rcpotto formation and, larger fossils fiom transition zone between, in 

Repetto .1:1 ills.-..------------------__.-...-..--------.- ... 

Pilsbry, H. A., acknowledgments to..........__..____________.--.____......_.

Pitaria Ida....................................................................

Plagiostoina................-.-.-----.-...-.-.....--......-.-.--.-..-...-.....

annulatus..-.----....--..--------------.-.------.---. --------------------

pedroana_.-...._......_.._..-.._..-_..._...____....._..._.....______.....

tru ncata.........-..........................------..--..........-----.--..

Pleurophopsis.....-..___.--._---.---.-..__._.....__..._.____-....__.______.__

Pleurotoma sp_..-..-..-....-.--....-.--...-.-......--......---.-.......-.....

PI icifususV....................................................................

(?) sp................................................................... 20

P ol iui ces......................................................................

Polyloptus, Pecten (Pseiidaiiiusiiini)--------------------------- ^.............

Poinaiilax.......__......._........_._._.__________.._____.._.___.____________

Priene.....-.-...-........-....--...-.-.---...................-.........--,--.

oregonensis var. angele.nsis ------........-...-.........-.-.-....--......

Propcamussium intorradiatnm.. ...........................................

protoxta,Donax?.....________________________________________________________

"Protocardia" cf. "P." centifllosa.......__...._._....___..._.________._.______

Pnunto lilills, outcrops of Repetto formation in... __.._____.._________._._____

52-53 

51 

51 

37

38-39 

, pi. 6 

56-57

56 

pi. 9

57

. 57 

56

56-57 

51 

51 

53 

53

50-52

pi. 5

pi. 5

17

£0 

2

55 

48 

37 

37 

37 

51 

26 

26

pi. 5 

23 

37 

22 

24 

23 

40 

28 

20 

4

quadragenariuin. Trachyeardiuin (Dallocardia) cf .................. 20, 53-54, pi. 9

R

radians, Calyptraoa a(T_..... .-...._.....__.___.........___._____________ 20

"Radiolites"_.............................................................. 7

hamlini_.............._..-.._-...._-__._.......___.__._.._._..__________ 6

randolphi, Hyalopocten (Delectopecten) afl.............................. 35-41, pi. e

Pecton..-...................-......--.................................._. 37

Riilhbun, M. J., acknowledgments io.,.....^.......^........................ 2

reclusiana, Nevorita all'..__-..---..._-.-....._______....._____.._.___.______ 20

Rohder, H. A., acknowledgments to.......................................... 2

Repotto formation, general features and outcrops of........................... 3-<i

land-plant debris in__..----..-.-......-------..--....-.................. 16

larger fossils from......................................................... 6-u

age relations of..................................................... 18,20-22

bearing of, on geologic history of Los Angeles Basin.-.....---....-.-.... 17-18

depth range of modern species allied to........................... 12-13, pi. 3

distribution of, at different depth facies.......................... 16, pi. 4

from outcrop localities................................................ 6-7,8

from subsurface localities.......................................... 7-3,9-10

inferred depth range of_---.----...._........__._____.._....._______ 13-15

inferred environment of..............................._........._..... 12-18

paloogoographic implications of........................................ 10-17

larger fossils of deep-water facies from..................................... 13-15

ago relations of._.................................................... is, 20

interpretation of.......-------........................................ 15-10

larger fossils of intermediate and shallow-water facies, age relations of..... 20-22

larger fossils of intermediate-depth facies from__........................ 13

larger fossils of shallow-water facies froin.................................. 13

occurrence of, in Los Angeles............................................. 5

subsurface section of, in Los Angeles Basin.............,...r .........._ 5-0

Page 

Re'petto Hills, outcrops of Kepetto formation in............................... 4

Repetto and Pico formations in, larger fossils from transition zone between. 20

San Joaquin Hills, outcrops of Repetto formation in.......................... 4

sanjuanensis, Pecten (Pseudamusium) vancouverensis ____.-.--..-.-----.- 38

Santa Monica Mountains, outcrops of Repetto formation in....-------------- 5

Schevill, W. E., acknowledgments to.-.----.................................. 2

scotiaensis, Argobuccinuni .--.-.-.----------------------.------------------- 24

semirostrata, Acila (Acila).......--------------.------------------------- 20, 28, pi. 5

Senilia ......-..........-.... .....................--------------.-.......-.----.---------------- 30

sequens, Ostrea vespertiua var. 

sicarius, Solen cf._--........

Soleuiya.-.........-...........

..-..--------------------------.-.-.---.. 44

...........-.-._-.. ..----- - 20

......................................... 27-28

agassizi_ ....-.--........-.-..-.----....-..-.....-..-..---------------- 27

dalli.... ................ --.. -- --- ------ -- 28

ventricosa................ ...........-.-.....----.........---.---------.--. 27-28

(Acharax) aff. S. johnsoni....-.-.. ..-- --- -~~~-.--~ -~ 27-28, pi. 5

Solemyacidae........-..............-..-------------------.-------.--.-------- 27-28

Solen cf. S. sicarius.--.__........----.... ....-....--.....----------.-.--- 20

Solenosteira angelensis........-....................--....--..-----.----------- 21

Spatangid echinoid.............-...---.....-...-.......-.-..-----.-.--------. 58

squamigerus, Aletes? of..------.---------------------------------------------- 20

stearnsii, Pecten.__.._................................................... 6

Periploma----.---.-.----------------------------------------------------- 56

Vesicomya__..-..........--..-.-.-....-.---.-.-.---...----------------- 51

stenopa, Periploma cryphia._----.--..--.-..----.---.---...----------...-.- 57

Stephanocyathus.------------------------------------------------------------ 7

Stephanotrochus.._...........-----.-...--.--.--.-.-.-.-.--..-.---.-.-.----- 7

"subauriculata," Limatula aff.___-----------.--.-.:.........-.-.---- 49-50, pi. 8

subcostata, Anomia__...................................................... 45

subdiaphana, Katherinella (Compsomyax) aff_..................... 20,54-55, pi. 6

T 

tenerrima, Callithaca aff____.---._..____._..._._..__.-_...-.--.-.---.--.--

terminus, Lyropecten estrellanus var. ......................................

Third Street tunnel, Los Angeles, fossils from_.............................

thraciaeformis, Yoldia aff______.........................................

tillamookensis, Hyalopecten (Delectopecten) randolphi aff......... . 41-42,

Pecten (Pseudamusium) raudolphi var...____........................

townsendi, Nassa..-----.--.-...---------.-.-.-----.---..----.----------------

Trachycardium_............................................................

(Dallocardia) cf. T. quadragenariuni............................. 20,53-54,

trilineata, Anadara aff____....-........-...................-.-.-.----.---.

Area___................................................................

Triton cancellation.... ..................^....................................

Truncacila?_...............................................................

truncata, Plagiostoina____;......-.-..........................-.-.....-....

turbanica, Astraea_.........................................................

Turbinidae..._.............................................................

Turritella cf. T. cooperi.......................................................

cf. T. goniostoma...........--.-.-.....-.-.-..............--......-....-..

U 

Uca liamlini................................................................... 6,11

V

vancouvereusis, Pecteu (Pseudamusium)---.-.-.-.-...............---..-.---. 37

vaiiwinkleae, Pecten_____................................................ 40

Varicorbula__-'.-..-...........-................................-....---.-.- 55-56

20 

34

2,6,8

17,20

pi. 6

37

25

53-54 

pi. 9 

20 

31 

24 

29 

37 

?2 

22 

20 

20

veatchii, Ostrea__.......................................................... 45

Veneridae____.-.----.-......-.-.....-..-.-.-.-.............-..-..---..-... 54-55

ventricosa, Solemya...._.................................................... 27-28

Venus angustifrous--.__-'-.........-...-.-.................................. 54,55

"Venus" breviliueata_.........-.---.-.........-.............--.-..--.---..- 54-55

Vertipecten__............................................................... 35

Vesicomya..___._........................................__........... 51

lepta ____...........___..........................___......... 50-51

ovalis.._..._...__-....-..__....._....___..-...-...-.._.__ 52

stearnsii.__............................................................ 51

Vesicomyacidae___-.-.........---.-.-......................-..-...-.-.-.-.. 52

Vesicomyacidae?_. ---.-..-....---.-.---..-.....-..............-..-.--.-.-. 50-52

vespertina, Ostrea..._._______.....___................_ 21,42-47, pis. 8,9

viridum, Bucciuum___......--..-.--.....-.-................--.-.---.-.--. 26

\V 

Wissler, S. Q., acknowledgments to_....................................... 1-2

Y 

Yoldia cf. Y. cooperi_._....-----.-.--.-..................--.---.-.-....-- 20

aff. Y. thraciaeformis.__._.__......................._.........__ 17,20

zacae, Pecten (Delectopecten).. 

zonalis, Limopsis_____.....

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