Cenozpic Pectinids of 

Alaska, Iceland, and 

Other Northern Regions

GEOLOGICAL SURVEY PROFESSIONAL PAPER 553
Cenozoic Pectinids of 

Alaska, Iceland, and 

Other Northern Regions

By F. STEARNS MAcNEIL

GEOLOGICAL SURVEY PROFESSIONAL PAPER 553

Evolution of indigenous Alaskan pectinid stocks^ 

of migrant stocks from other areas in the Pacific 

region^ and of boreal Pacific species that subsequently 

migrated to the Arctic and northern Atlantic regions

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEW ART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

Library of Congress catalog-card No. GS 66-321

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

Washington, D.C. 20402 - Price $1.00 (paper cover)
CONTENTS

Abstract_ ________________________________________

Introduction. ______________________________________

Pectinidae as guide fossils__________________________

Pectinidae of Alaska._______________________________

Migration routes__________________________________

Systematic concept.________________________________

Systematic paleontology.____________________________

Genus Delectopecten Stewart______________________

Delectopecten maddreni MacNeil, n. sp_________

Genus Polynemamussium Habe___________________

Polynemamussium alaskense (Dall)____________

Polynemamussium davidsoni (Dall)____________

Genus Arctinula Thiele__________________________

Arctinula groenlandica (Sowerby)_____________

Genus Chlamys Roeding-________________________

Subgenus Leochlamys MacNeil, n. subgen______

Chlamys (Leochlamys) tugidakensis MacNeil 

n. sp________________________________

Subgenus Swiftopecten Hertlein_______________

Chlamys (Swiftopecten) donmilleri MacNeil, 

n. sp________________________________

Chlamys (Swiftopecten) cf. C. (S.) donmilleri 

MacNeil___________________________

Chlamys (Swiftopecten) sp _______________

Chlamys (Swiftopecten) swifti kindlei (Dall) _ 

Subgenus Chlamys Roeding-_________________

Group of C. ("C.") hastata (Sowerby) _____

Chlamys ("Chlamys") hastata (Sowby) _____________________________

Chlamys ("Chlamys") hastata hericius 

(Gould)__.______________________

Chlamys ("Chlamys") pugetensis (Oldroyd) ------_________________

Group of C. ("C.") tauroperstriata Sacco____

Chlamys ("Chlamys") harmeri Altena__

Chlamys ("Chlamys") breidavikensis

MacNeil, n. sp___________________

Group of C. ("C.") gloriamaris (Dubois)___ 

Chlamys ("Chlamys") tjornesensis MacNeil, n.sp_______________________

Group of C. ("C") cosibensis (Yokoyama).

Chlamys ("Chlamys") cf. C. ("C.")

cosibensis (Yokoyama) __ _ _________

Chlamys ("Chlamys") coatsi MacNeil, 

n. sp____________________________

Chlamys ("Chlamys") coatsi middletonensis MacNeil, n. subsp.________

Chlamys ("Chlamys") cf. C. ("C.") 

coatsi middletonensis MacNeil_______

Chlamys ("Chlamys") chaixensis MacNeil, n.sp_______________________

Chlamys ("Chlamys") lioica (Dall)____

Chlamys ("Chlamys") trinitiensis MacNeil, n. sp_______________________

Chlamys ("Chlamys") aff. C. ("C.") 

trinitiensis MacNeil.______________

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Systematic paleontology Continued 

Genus CMamys Roeding Continued

Subgenus CMamys Roeding Continued Page 

Group of C. (C.) rubida (Hinds)..________ 21

Chlamys (Chlamys) rubida (Hinds)____ 21

Chlamys (Chlamys) rubida jordani (Arnold) 22

Chlamys (Chlamys) rubida hindsii (Carpenter) __________________________ 23

Chlamys (Chlamys) cf. C. (C.) rubida

hindsii (Carpenter)_______________ 23

Chlamys (Chlamys) rubida prerubida

MacNeil, n. subsp________________ 23

Group of C. (C.) beringiana (Middendorft) _ _ 24

Chlamys (Chlamys) beringiana (Middendorff) _________________ 24

Chlamys (Chlamys) beringiana colvillensis MacNeil, n. subsp____________ 26

Chlamys (Chlamys) beringiana graui

MacNeil, n. subsp_________-______ 26

Chalmys (Chlamys) beringiana strategus (Dall). ------------------- 26

Chlamys (Chlamys) beringiana unalaskae MacNeil, n. subsp__ ___________ 27

Chlamys (Chlamys) wainwrightensis

MacNeil, n. sp___________________ 27

Group of C. (C.) picoensis (Waterfall) _ _ _ _ _ 28

Chlamys (Chlamys) picoensis (Waterfall) -.------------------------ 28

Chlamys (Chlamys) cf. C. (C.) picoensis

chinkopensis Masuda and Sawada___ 28

Chlamys (Chlamys) picoensis kinoshitai Kubota_--_-------_-------- 29

Group of C. (C.) hanaishiensis Masuda____ 29

Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda__---_-_---------_ 29

Chlamys (Chlamys) hanaishiensis amchitkana MacNeil, n. subsp________ 30

Chlamys (Chlamys) pseudislandica MacNeil, n. sp_--------------_------- 31

Chlamys (Chlamys) pseudislandica plafkeri MacNeil, n. subsp____________ 32

Chlamys (Chlamys) pseudislandica arconis MacNeil, n. subsp___________ 33

Group of C. (C.) islandica (Muller)________ 33

Chlamys (Chlamys) islandica islandica

(Muller) 33

Chlamys (Chlamys) islandica thulensis

MacNeil, n. subsp__________-----_ 34

Chlamys (Chlamys) islandica kanagae

MacNeil, n. subsp_______________ 35

Chlamys (Chlamys) islandica powersi

MacNeil, n. subsp_______-_------- 35

Chlamys (Chlamys) islandica erythrocomata (Dall)_______----__----_-- 36

Chlamys (Chlamys) islandica albida

(Dall) 36

in
IV CONTENTS

Systematic paleontology Continued

Genus CMamys Roeding Continued page 

Subgenus CMamys Roeding Continued

Other species assigned to Chlamys. ________ 36

Chlamys sp___-__---______-------__ 36

Chlamys (?) washburnei (Arnold) _____ 36

?Chlamys sp______________________ 37

Chlamys"! nuwokensis MacNeiL_______ 37

Genus Vertipecten Grant and Gale________________ 38

Vertipecten lachenbruchi MacNeil, n. sp________ 39

Vertipecten popofensis MacNeil, n. sp __________ 39

Vertipecten n. sp.7-------------------------- 40

Genus Patinopecten Ball._________-________----__ 40

Subgenus Patinopecten Ball._________________ 41

Patinopecten (Patinopecten) cf. P. (P.)

caurinus (Gould)_____________________ 41

Systematic paleontology Continued

Genus Patinopecten Dall Continued page

Subgenus Lituyapecten MacNeil-_____________ 41

Patinopecten (Lituyapecten) n. sp________ 41

Subgenus Mizuhopecten Masuda._____________ 41

Patinopecten (Mizuhopecten) skonunensis

MacNeil, n. sp_______________________ 42

Genus Fortipecten Yabe and Hatai._______________ 42

Fortipecten mollerensis MacNeil, n. sp_ ________ 43

Fortipecten hallae (Ball)_____________________ 44

Genus Miyagipecten Masuda.____________________ 44

Miyagipecten alaskensis MacNeil, n. sp_ _______ 45

Localities. _________________________________________ 45

References.________________________________________ 49

Index _____________________________________________ 53

ILLUSTRATIONS

[Plates follow index] 

PLATES 1-25. Pectinids from 

1. Aleutian Islands, Alaska Peninsula, Katalla district* (Alaska).

2. Alaska Peninsula, Shumagin Islands (Alaska).

3. Alaska Peninsula, Seward Peninsula, Yakataga district (Alaska).

4. Alaska Peninsula, Yakataga district, Malaspina district, Arctic coast (Alaska), Queen 

Charlotte Islands (British Columbia).

5. Alaska Peninsula, southeastern Alaska, Katalla district (Alaska).

6. Aleutian Islands, Malaspina district, Lituya district, Arctic coast (Alaska), Queen 

Charlotte Islands (British Columbia).

7. Trinity Islands, Middleton Island, Lituya district (Alaska).

8. Trinity Islands, Middleton Island (Alaska).

9. Trinity Islands, Yakataga district (Alaska).

10. Yakataga district, Lituya district (Alaska).

11. Trinity Islands, Middleton Island, Lituya district (Alaska).

12. Middleton Island (Alaska).

13. Middleton Island (Alaska).

14. Aleutian Islands, Middleton Island (Alaska).

15. Aleutian Islands, Arctic coast (Alaska).

16. Aleutian Islands, Trinity Islands, southeastern Alaska (Alaska).

17. Aleutian Islands (Alaska).

18. Aleutian Islands, southeastern Alaska, Seward Peninsula, Arctic coast (Alaska), 

Greenland, Iceland.

19. Southeastern Alaska, St. Lawrence Island, Arctic coast (Alaska), Iceland.

20. Aleutian Islands, Alaska Peninsula, Arctic coast, southeastern Alaska (Alaska).

21. Puget Sound (Washington), southeastern Alaska, Pribiloff Islands (Alaska), Okhotsk 

Sea.

22. Aleutian Islands, Sitkalidak Island off Kodiak, southeastern Alaska (Alaska), California.

23. Arctic coast (Alaska).

24. St. Lawrence Island, southeastern Alaska (Alaska), ?Bering Sea, California, Kurile 

Islands, Iceland, Netherlands.

25. Iceland.

*Katalla district, Yakataga district, Malaspina district, and Lituya district are west to east in the outcrop of Tertiary rocks bordering the 

northern Gulf of Alaska.
CENOZOIC PECTINIDS OF ALASKA, ICELAND 

AND OTHER NORTHERN REGIONS

By F. STEARNS MAC^EIL

ABSTRACT

Oligocene to Recent pectinids from Alaska contained in the 

collections of the U.S. Geological Survey are herein described 

and figured. New species from Iceland and the Queen Charlotte 

Islands, British Columbia, and a new subspecies from Greenland 

are included. This paper also contains the first published figure 

of the holotype of Pecten (Chlamys) erythrocomatus Dall and 

the first published photograph of the lectotype, herein designated, 

of Pecten islandicus var. behringiana Middendorff.

An attempt is made to determine the closest relatives of Alaskan species in other areas, as well as to determine the phylogenetic and geographic origin of Alaskan species. Several 

species or species groups are believed to have migrated from the 

Pacific to the Atlantic in late Cenezoic time, but so far no unequivocal case of an Atlantic pectinid entering the northern 

Pacific by way of the Arctic seas is known. Most Alaskan pectinids have older and more southern relatives in the Pacific, particularly in East Asia. At the same time, some Pacific middle 

Tertiary species have a striking similarity to European middle 

Tertiary species. It is suggested that some early and middle 

Tertiary pectinid stocks in the northern Pacific were of European 

origin but that they reached the northern Pacific by a Tethyan 

or Indian Ocean route rather than by way of the Arctic; subsequently, some of these stocks remigrated to northern Atlantic 

waters across the Arctic. Migration by a southern route has 

been demonstrated in the group of Pecten jaco'baeus.

INTRODUCTION

This report, together with an earlier paper on the subgenus Lituyapecten (MacNeil, 1961), completes a study 

of the Cenozoic Pectinidae from Alaska contained in the 

collections of the U.S. Geological Survey. In addition 

to its own accumulation of the past 70 years, the Geological Survey is the repository for large collections made 

by the Gulf Oil Co., the Eichfield Oil Co., and the British Petroleum Exploration Co. Several pectinids from 

Alaska were donated by the Shell Oil Co. A new Miocene species from the Queen Charlotte Islands in the collection of the University of California at Los Angeles is 

also described.

The Kecent northern Pacific pectinids, both American 

and Asiatic, that range to Alaska or that have bearing 

on Alaskan species are included in the systematic treatment. Several subspecies of Chlamys 'islandica (Miiller) are recognized in the Pacific, but typical C. islandica 

is not regarded as a living Pacific subspecies. This

paper contains the first published illustration of the 

holotype of Pecten (Ghlamys) erythrovomatus Dall 

from the Okhotsk Sea and the first published photograph of the lectotype, herein designated, of Pecten islandwus var. behringiana Middendorff. An attempt is 

made to rectify the nomenclature of northern Pacific 

pectinids in view of recent Japanese contributions, but 

admittedly a much better knowledge of the Eussian 

Asiatic forms will be necessary before a wholly 

satisfactory integration can be made.

I am indebted to Dr. Leo G. Hertlein, of the California Academy of Sciences, for frequent consultations 

and advice during the preparation of this paper and for 

permission to figure several Recent specimens in the 

Academy collections. The photographs of the holotype 

of P. (G.} erythrocomatus Dall were obtained by him 

several years ago from Dr. Paul Bartsch, of the U.S. 

National Museum. Dr. A. O. Scarlato, Zoological Institute, Academy of Science, Leningrad, kindly supplied 

me with photographs of two specimens figured by Middendorff, one of which is here designated the lectotype 

of Pecten islandicus behringianus Middendorff. Dr. 

Willis P. Popenoe, of the University of California at 

Los Angeles, kindly gave me permission to describe the 

new species from the Queen Charlotte Islands. I am indebted also to Dr. Thorleifur Einarsson, of the University Research Institute, Reykjavik, Iceland, for specimens of G. islandica from. Iceland. Kenji Sakamoto, 

of the U.S. Geological Survey, made all the 

photographs.

PECTINIDAE AS GUIDE FOSSILS

With the possible exception of the ammonites, no 

group of mollusks has been the subject of as many monographic studies as the Pectinidae. Comparatively few 

faunas, Recent or fossil, have been described in which 

there are no pectinids, and in many faunas the Pectinidae constitute the largest single group. Pectinids, like 

oysters, have a calcitic shell, and calcitic shells may be in 

evidence long after the aragonitic elements of a fauna 

have dissolved; it is fairly common for the oysters and 

pectens to be the only shells preserved in Tertiary strata.
CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

While the modern technique of obtaining rubber casts 

from natural molds has obviated the difficulty of finding 

well-preserved shells the pectens may even be dissolved 

purposely to obtain good molds the durability of pectinid shells has probably been a large factor in determining the degree to which the group has been studied.

If all Tertiary stratigraphic studies were to be based 

on one group of mollusks and one alone, that group 

would undoubtedly be the pectens.

The Pectinidae exhibit a remarkable conformity to 

gross morphological plan. Unlike some other pelecypods, their family allocation is obvious from their external characteristics; both the Pectinidae and the supposedly ancestral Aviculopectinidae are instantly recognizable as pectinoid. Other related Paleozoic families 

are intermediate between the pectinids and the pteriids. 

So enormously complex is this group, however, that we 

still know very little of either its evolutionary pattern 

or its internal relationships. The comparatively narrow boundaries of diversification within the Pectinidae 

make it likely that similar morphological types evolved 

time and time again.

Distantly related genera such as GJilamys and 

Propeamussium probably represent groups that have 

been distinct since Paleozoic time, but it is not clear 

how far back most pectinid lineages must be traced to 

find a common ancestor. Ohlamys-IikQ forms are 

known in Mesozoic time. CJilamys splendens (Dollfus) (see Arkell, 1931, pi. 10, figs. 1-5) from the 

Jurassic is surprisingly like some late Tertiary and 

Recent CJilamys. While one is tempted to accept 

such forms as primitive GJilamys, few known Late 

Cretaceous or Eocene species are as similar to modern 

GJilamys. It is not at all certain, furthermore, that 

typical Pecten of the Tertiary, a genus having an externally convex right valve and a concave left valve, 

is descended from similar forms in the Cretaceous, 

such as NeitJiea quinquecostatus (Sowerby) (see 

Wade, 1926, pi. 21, figs. 1-5). Neither is it certain 

that all modern so-called Pecten (Pecten} are monophyletic. I cannot find an Eocene species that I 

would refer to Pecten (Pecten). Pecten poulsoni 

Morton from the Marianna Limestone (early middle 

Oligocene) of Alabama is Pecten-liks, however, and 

it probably evolved from a late Eocene stock that 

was more equivalved and OJilamys-\^ke>.

Probably no other superfamily of Mollusca is as 

ubiquitous or spans as long a period of time as the 

Pectinacea. The Pectinidae come as close as any 

other family of mollusks to duplicating the complexity of the Mesozoic ammonites. In both the larval 

and adult stages, the pectinids are active swimmers; 

if dead shells had been dispersed as widely as those

of the modern nautiloids, the pectinids might have 

exceeded the ammonites in their value as stratigraphic 

markers.

PECTINIDAE OF ALASKA

Alaska was the site of the first recorded observation (La Perouse, 1797, p. 189; Miller, 1961) of a 

fossil pectinid in western North America, the 

"manteau royal" seen by members of La Perouse's expedition of 1786 in the rocks of Cenotaph Island, 

Lituya Bay. Grewingk (1850, p. 99-100; Miller, 

1961) cited this observation as evidence for the occurrence of Tertiary strata along the northeastern 

border of the Gulf of Alaska. The species was described by MacNeil (1961) as Patinopecten (Lituyapecteri) lituyaensis. Pecten propatulus Conrad 

(1849), from Oregon, appears to have been the first 

western North American fossil pectinid to be described ; the first fossil pectinid described from Alaska 

was Pecten (CJilamys] lioicus Dall (1907), a species 

from upper Pliocene or lower Pleistocene beds at 

Nome.

Two of the earliest described western American 

Recent species came from Alaska and Bering Sea: in 

1845, Hinds described Pecten rubidus from Sitka, and 

in 1849 Middendorff described Pecten islandicus 

~behringianus from somewhere in Bering Sea. The 

only species described earlier from western America 

were some tropical and subtropical species of 

Sowerby and d'Orbigny.

Before Dall (1898, p. 699-812) undertook the first 

systematic revision of all known pectinids of western 

America, numerous fossil and Recent species had been 

described, mostly by Conrad, Gould, and Dall. The 

literature was sparse at that time, some of it in papers 

now rare. Arnold (1906) published the first really 

important paper on western American pectinids, a 

paper that is still the primary reference. This paper 

describes many new species and figures most of the 

previously described species, including several type 

specimens not previously illustrated. The next significant revision of the fossil species was by Grant 

and Gale (1931), and a comprehensive treatment of 

the Recent species was much later undertaken by 

Grau (1959). Dall, Arnold, Grant and Gale, and 

Grau all included Alaskan species in their revisions. 

The large amount of Cenozoic material that has accumulated in the collections of the U.S. Geological 

Survey since Dall's time contains many new forms, 

however, and the much larger suites of shells make 

possible a study of varietal ranges that could not have 

been accomplished a few years ago.

In addition to American studies on Alaskan 

pectinids, there are several important Japanese papers
MIGRATION ROUTES

that deal directly or indirectly with Alaskan species. 

By far the greatest number of Japanese contributions are by Masuda, but other important papers have 

been published by Masuda and Hatai, Masuda and 

Sawada, Akiyama, Oyama, Kubota, and others. The 

long-continued practice of referring certain Kecent 

Alaskan forms to Chlamys islandica (Muller) has 

dissuaded American authors from naming them. 

Consequently, some Alaskan species that range continuously along the eastern Asiatic coast have been 

named in Japan. However, several other American 

species names have many years' priority over Japanese 

names for very similar forms. Some of these 

Japanese species are here treated as subspecies of the 

earlier American species.

MIGRATION ROUTES

Theoretically, the direction of migration of mollusks that have pelagic larvae should be controlled by 

oceanic circulation. Throughout Tertiary time, new 

molluscan stocks have made abrupt and sometimes 

termporary appearances in the waters of western 

North America. Because most of these stocks have 

older representatives in Japan, it is presumed that 

they are immigrants from East Asia. These apparent 

first arrivals are found from the Alaska Peninsula 

to California. During Oligocene time the fauna of 

the Alaska Peninsula region was predominantly 

Asiatic.

It seems likely that these Asiatic faunas were 

brought to America by the Japan Current or some 

similar current that flowed eastward in Tertiary time. 

At the present time the Japan Current flows almost 

due eastward at about the latitude of Vancouver, and 

near the American coast it divides into northward 

and southward flowing branches. There are no 

known early Tertiary marine deposits north of the 

Alaska Peninsula, however, and it is suggested that 

all or most of the Bering Sea was land in early 

Tertiary time. Such a difference in basinal configuration, especially the absence of the basin that now accommodates the counterclockwise Subarctic Current, 

would almost certainly have had some effect on the 

main clockwise circulation in the northern Pacific, 

and especially on the terminal distribution of the 

main currents. It is suggested that the main Japan 

Current coursed the present Alaska Peninsula and the 

present northern shore of the Gulf of Alaska in early 

Tertiary time and that its present location is due in 

part to deflection by the modern Subarctic Current.

Migration patterns for most northern Pacific mollusks are still unknown. It is fairly well established, 

however, that many boreal and north temperate species

range farther north on the Alaskan coast and that 

typically Arctic species range farther south along the 

Siberian coast. Fortipecten is known in upper Tertiary (?) beds at Kivalina, and Natica janthostoma 

occurs in upper Pleistocene beds at Cape Kruzenstern. 

Chlamys- (Swiftopecten] occurs in middle Pleistocene 

beds at Nome. As far as is known, none of these forms 

is found in beds of comparable age in the Chukotsk 

Peninsula. Conversely, Bathyarca glacmlis, an Atlantic and Arctic species, is reported from several localities 

near Kresta Bay in southwestern Chukotsk; these are 

only known occurrences south of Bering Strait. B. 

glacialis has been found only once in Alaska, in a test 

well near Cape Simpson east of Point Barrow where 

it occurs in about the middle part of the Gubik Formation (horizon probably about middle or upper Pleistocene) .

How the counterclockwise circulation in Bering Sea 

could be responsible for this distribution of organisms 

when most of the flow in Bering Strait is north is not 

clear. According to Johnson (1956, p. 14), longshore 

currents along eastern Arctic Siberia have been reported to continue eastward to Kotzebue Sound on the 

Alaskan coast. If such a flow exists, it must merge 

with the northward flow through Bering Strait. Johnson concluded that the currents along northeastern 

Siberia more probably are deflected northwestward 

toward Herald Shoal. Some southward flow along the 

west side of Bering Strait is indicated, but whether it 

is seasonal and whether the anomalous distribution of 

the Pleistocene fossils is due to currents that no longer 

exist is not known.

The currents of Bering Sea and the Arctic Ocean, 

even when they are more accurately known, may not 

be a reliable model for currents of the past. Currents 

can and probably do increase, decrease, or shift their 

course with changes in basinal configuration. Seasonal 

variation in existing Arctic currents suggests that Arctic circulation could have been entirely different in past 

periods when the Arctic had less ice or was ice free. 

The distribution of species during the Pleistocene, particularly along the Arctic coast, is not what might be 

expected if existing currents prevailed. Judging from 

the molluscan faunas, at least one stage of the Pleistocene was characterized by two-way circulation in Bering Strait; there was a southward flow on the Asiatic 

side that rounded Chukotsk and entered the Anadyr 

Gulf and a northward flow on the American side that 

rounded Point Barrow and flowed eastward along the 

Arctic coast. At the present time (Johnson, 1956), the 

main plankton stream is due north from Bering Strait. 

A weak, possibly seasonal, eastward-flowing longshore
CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

current may exist east of Point Barrow, but the main 

circulation in Beaufort Sea is clockwise.

SYSTEMATIC CONCEPT

A few decades ago it was fashionable and appropriate to categorize molluscan systematists as either 

"lumpers" or "splitters," depending on whether they 

favored broad 'taxonomic groupings or tended to recognize each morphological variant as an entity. From 

either viewpoint, the systematists of that era were typologists; their concept of species was based on type specimens or on figures which provided the only available 

knowledge of a taxon.

In recent years, the population concept of systematics 

has largely supplanted the type concept. The population concept is largely the concept of variability; in 

such a concept the type specimen is not necessarily 

typical of a species and could conceivably be the most 

atypical member of a species; types are often chosen 

solely on the basis of preservation. The type specimen 

has value in the population concept only as a nomenclatural reference; it is the bearer of the name that is given 

to the group within which it falls.

Paradoxically, the modern-day paleontologist is regarded by most contemporary neontologists as a typologist of the "old school." If paleontologists are typologists, it is only under those circumstances where typology is necessary; thousands of fossil species are known 

only from the type specimen. The space-time systematics with which the paleontologist works, however, leads 

him inevitably to the concept of variability as a constant. The neontologist by definition deals with the 

systematics of one instant of time. To him the variation within populations is deviation from a norm; at 

best it is an annoying circumstance that makes difficult 

the orderly demarcation of species. To a paleontologist the range of variation is the norm; deviation occurs 

at another instant of time when the range of variation 

is different.

The systematic categories of any past instant of time, 

if viewed alone, might differ in rank from those of 

another instant. Most paleontologists probably would 

agree that if they could be projected back in time and 

were to classify the fauna of the late Paleozoic as neontologists, the Recent Orders of mollusks would be no 

more than Families or Subfamilies. Two Eecent 

species between which there is no present morphological 

continuum may be represented in Pleistocene time by 

geographical subspecies; each of the geographical subspecies might have an identical variant, but each would 

have other variants unlike variants in the other subspecies. In still earlier time, the two subspecies may be 

traceable to individual variants in a single population.

The limit of fertile breedability is known for veryfew Recent animals, and it will never be known for fossils. Nevertheless, the individuals in a given area that 

appear to be connected by an unbroken series of variants 

can be regarded, reasonably, as constituting a single 

taxon. Apparent morphological and geographical 

limits are still the soundest criteria for determining the 

boundaries of species and subspecies. Only those 

boundaries marked by a broad geographical hiatus are 

exempt from personal opinion. The systematist has the 

task, therefore, of determining the morphological and 

geographical boundaries of species, as well as the apparent varietal connectives between species. The position of the holotype within a species is of secondary concern. It becomes important only when a combination 

of taxa or the subdivision of a taxon is necessary, in 

other words, when the application of a name is involved.

In such a situation it is obvious that the final word 

on phylogeny cannot be had until the complete range 

of variation in all populations, in all areas, and at all 

instants of time is known. Every varietal series is 

potentially the ancestor of two or more species, depending on accidents of isolation due to migration or ecology 

or to possible genetic barriers a population might develop within itself. Nearly identical variants can occur 

in two or more populations which have different ranges 

of variation and which are separated in either space or 

time. It is to such nearly identical variants that we 

must look for evidence of both relationship and origin. 

The direction of evolution in closely related forms is 

often difficult to determine from morphology alone. An 

older population may reveal immediately, however, 

which variant in a younger population is more primitive.

Despite the large number of pectinids recorded thus 

far from both the American and Asiatic sides of the 

Pacific, it is still very difficult to see how they are interrelated. With very few exceptions, the statements 

made here concerning their relationships must be regarded as tentative.

The dependence of our taxonomic concept on nomenclatural priority has resulted in some unfortunate combinations of species and subspecies names. More or less 

provincial studies oil opposite sides of the Pacific have 

complicated rather than clarified the picture. While 

the status of some American species is unsatisfactory 

and cannot be resolved yet with any degree of finality, 

their relationship to Asiatic forms involves even greater 

problems. I certainly am not convinced that the eastern 

Asiatic species are as endemic as Masuda (1963) sugguested. Taxonomy could be made less cumbersome by 

the elimination of subspecies, but the resulting loss of 

nomenclature as a means of showing both relationships 

and trends in evolution would be undesirable. Many
SYSTEMATIC PALEONTOLOGY

relationships and most evolutionary and migrational 

patterns could be expressed with less confusion, however, if species and subspecies were not coordinate, that 

is, if the rules permitted the use of a junior name for 

the species and a senior name for the subspecies.

SYSTEMATIC PALEONTOLOGY

Genus DELECTOPECTEN Stewart, 1930

Palliolntn (Delectopecten) Stewart 1930, Acad. Nat. Sci. Philadelphia Spec. Pub. 3, p. 118.

Type species (by original designation) : Pecten 

(Pseudamusium] vancouverensis Whiteaves. Recent 

Sitka Harbor, Alaska, to Catalina Island, Calif.

Discussion,. Most recent authors have referred mud 

pectens of this kind to Delectopecten. The type species 

of Delectopecten has moderately strong radial sculpture 

on both valves. Some other species, such as D. randolph i 

(Dall), living from Washington to southern California, 

are hyaline and have concentric undulations only; Grau 

(1959, p. 44, pi. 16, figs. 4, 5) treated this species as 

Oyclopecten (Delectopecten} randolphi (Dall). As 

presently construed, the genus Delectopecten contains 

species with moderately strong radial or reticulate sculpture, species with radial rows of beads but no welldefined ribs, and species without radial sculpture on 

the disc; the species that have no radial sculpture on the 

disc may have moderately strong concentric undulations. The smooth species usually have radial threads 

on the anterior ear of the right valve. There are no 

internal ribs. The posterior ears of Delectopecten are 

not set off by an indentation; the margin of the ear is 

nearly tangential to the adjacent curved outline of the 

margin of the shell. The posterior ears of Oyclopecten 

are separated from the margin by an indentation.

If and until it can be shown that there is a close relationship, if not a morphological continuum, between 

Oyclopecten and Delectopecten, it might be better to 

regard them as separate genera. While some species of 

Delectopecten, such as D. polyleptus (Dall) (Grau, 

1959, pi. 16, fig. 1), have radial rows of beads, these 

beads do not resemble the radial rows of hollow blisters 

found on the type species of Oyclopecten (Pecten pustulosus Verrill; Verrill and Bush, 1898, p. 839, pi. 85, figs. 

5, 6, 10, 11). G. pustulosus has well-defined posterior 

ears set off by a moderately deep indentation. Verrill 

and Bush (1898, p. 839) stated that C. pustulosus does 

not have internal ribs as does Propeamussium hoskynsi, 

a species which is presumably the Pecten hoskynsi of 

Sars (1878, pi. 2, figs, la-c). If P. hoskynsi has internal 

ribs, it may prove to be a Polynemammsium and probably is not a synonym of Cyclopecten imbriferum 

(Loven) (Ockelmann, 1958, p. 66, pi. 2, fig. 1). I 

cannot, however, find a figure of the interior of either

P. hoskymi or O. imbriferum, and until their internal 

shell features are clarified, the whole discussion might 

better be postponed.

Delectopecten maddreni MacNeil, n. sp. 

Plate 4, figure 5; plate 5, figure 5

Description. Shell small; disc has faint concentric 

growth lines and four or five crude concentric undulations ; no radial sculpture. Anterior ear of right valve 

has 11 or 12 fine radial riblets; posterior ear unknown. 

Anterior ear of left valve slightly convex along its anterior border, the border nearly vertical; posterior ear 

smaller, the posterior border sloping at about 45°, 

weakly concave.

Discussion. This species is closely related to 

Delectopecten peckhami (Gabb) as that species was interpreted by Arnold. (See Moore, 1963, p. 67.) The 

available figures of D. peckhami show about 4 to 6 riblets on the anterior ear of the right valve, whereas D. 

maddreni has 11 or 12 riblets. The California Academy 

of Sciences has some specimens identified as D. pedroanus (Trask) that have 10 to 12 riblets on the anterior 

ear. The distinction between D. peckhami and D. 

pedroanus is not clear, and some authors (Grant and 

Gale, 1931, p. 236) have combined them; certainly the 

type of D. pedroanus came from much younger beds 

than the type of D. peckhami.

According to Moore (1963, p. 67), the California occurrences of D. peckhami are all Miocene. Masuda 

(1962a, p. 164) recorded D. peckhami from late Oligocene to early Pliocene beds in Japan, and Slodkewitsch 

(1938, p. 113) gave a similar range for the species in 

Kamchatka.

Delectopecten maddreni occurs in beds that are probably of late Oligocene age. It is of about the same age, 

therefore, as the oldest of the Asiatic forms assigned to 

D. peckhami, and possibly these Asiatic Oligocene forms 

are closer to D. maddreni than to D. peckhami. D. 

maddreni appears to be more closely related to D. peckhami and D. pedroanus than to D. lUlisi (Hertlein) 

(1934, p. 5, pi. 1, fig. 1, pi. 2, figs. 2, 3) from the 

Kreyenhagen Shale (late Eocene and early Oligocene) 

of California. D. lillisi has about 10 fine spinose riblets on the anterior part of the disc of the right valve. 

An apparently undescribed species of Delectopecten occurs in the lower part of the Moreno Formation (Late 

Cretaceous and Paleocene?) of California (the horizon 

probably of Maestrictian age).

Types: The holotype (USNM 644865) consists of a right and 

a left valve which may or may not belong to the same individual; 

the slab on which they occur has many specimens close together. The right valve has a height and length of about 22 

mm. A figured specimen from the Poul Creek Formation is 

numbered USNM 644866.
6 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Type Ideality: Upper part of the Burls Creek Shale Member 

of the Katalla Formation (horizon probably upper Oligocene), 

Burls Creek, Katalla district, Alaska, USGS 4321.

Locality of figured specimen: Middle part of the Foul Creek 

Formation (horizon probably upper Oligocene), north end of 

spur projecting into Bering Glacier, about due north of the 

mouth of Kulthieth River, Yakataga district, Alaska USGS 

16898.

Genus POLYITEMAMTJSSIUM Habe, 1951

Polynemanwssium Habe, 1951, Genera of Japanese Shells, p. 

72, figs. 136,137.

Type species (by original designation) : Pecten intuscostatus Yokoyama. Pleistocene, Miyata Formation. Kanagawa Prefecture, Japan.

Discussion. Until Habe proposed the name Polynemamussium, there seems to have been no really appropriate taxon in which to include Pecten (Pseudoamussiuml) alaskensis Dall. Arnold (1906,p. 133) referred 

it to the subgenus Pecten (Propeamussiuin}. Since 

then Propeamussium, as a genus or subgenus, has been 

the most popular allocation of it. Grau (1959, p. 18) 

rejected the name Polynemamussium and treated Dall's 

species as Propeamussium (Parvamussium') alaskense 

(Dall). Both Propeamussium and Parvamussium 

have a few rather strong internal ribs that are widely 

spaced and appear, moreover, to be superimposed, calluslike, on a uniformly curved interior surface. The 

internal ribs of Pecten alaskensis are more numerous, 

are stronger toward the margin, and have interspaces 

that are round bottomed. While a few recent authors 

have used Pseudamussium and Pseudamussiurn (Gyclopecten) for this group, neither Pseudamussium, nor Gyclopecten has internal ribs. Masuda (1962b, p. 154), 

in his discussion of Polynemamussium, said, "This 

genus differs from Propeamussium by its conspicuous 

imbricated sculpture of the left valve, distinct byssal 

notch, and the internal ribs which become distinct near 

the ventral margin."

Oyama (1944, p. 245) proposed Squamamussium 

(type species, Amusium squamigerum E. A. Smith, Recent, West Indies) as a subgenus of Propeamussium. 

He included both Pecten alaskensis Dall and Pecten intuscostatum Yokoyama in Squamamussium along with 

three species from the Indonesian region. No subsequent Japanese author has accepted Squamamussium 

for a northern Pacific species. The type species (see 

Kiister and Kobelt, 1888, pi. 49, fig. 8) has fine radial 

ribs on the left valve, but without examining specimens 

I would hesitate to say whether it represents the same 

group as Polynemamussium.

Omori (1955) regarded Propeamussium and Parvamussium as different genera, and he also recognized 

Polynemamussium (which he spelled Polyneamussium} . His figures clearly show the nature of the internal ribs; they disappear distally in Propeamussium 

and Parvamussium, and they appear distally in Polyne- 

'mamussium. According to Masuda (1962b, p. 15 5), the 

specimens Omori figured as "Polyneamussium" alaskeme (ibid., pi. 2, figs. 2-14) are Polynemamussiwm intuscostatum.

Polynemamussium alaskense (Ball) 

Plate 5, figures 2-4

Pecten (Pseudoamussiuml) alaskensis, Dall, 1872, Am. Jour.

Conchology, v. 7, p. 155, pi. 16, fig. 4. 

Pecten (Propeamusium) alaskensis, Dall, 1886, Mus. Cornp.

Zoology Bull., v. 12, no. 6, p. 215, pi. 5, figs. 7, 7a. 

Arnold, 1906, U.S. Geol. Survey Prof. Paper 47, p. 133, pi. 53,

figs. 2, 2a, 3 (with extended synonymy). 

Pecten (Propcamusiutn) alaskense, Dall, 1921, U.S. Nat. Museum

Bull. 112, p. 20, pi. 1, fig. 2. 

Polynemamussiuin alaskense, Habe, 1951, Genera of Japanese

Shells, p. 72. 

Propeamussium (Parvamussium) alaskense, Grau. 1959, Alien

Hancock Pacific Exped., v. 23, p. 18, pi. 3 (with extended

synonymy). 

Polynemamussium alaskense, Masuda, 1962, Tohoku Univ. Sci.

Repts., 2d ser. (Geology), v. 33, no. 2, p. 155, pi. 18,

figs. 5a, b, 6a, b (with extended synonymy).

Discussion. Both the right and left valves of this 

species have weak internal riblets that become stronger 

distally, but only the left valve has riblets on the exterior. The number of external riblets is variable, 

ranging usually from 24 to 30. Some of the riblets tend 

to become weakly beaded or scabrous toward the margin. The riblets have little relief and tend to merge 

with the interspaces; usually they are lighter colored 

than the remainder of the disc. All the ears have weak 

radial riblets, but such riblets are stronger on the 

anterior ear of the right valve.

Polynemamussimn intuscostatum (Yokoyama) 

(Masuda, 1962b, p. 156), a related species from the 

early Pliocene to Recent of Japan, is more coarsely 

sculptured than P. alaskense and the riblets are more 

beaded. Kamio (1962, p. 56, pi. 4, figs. 6, 7) reported 

P. alaskense from the Setana Formation (early Pliocene) of Hokkaido. Masuda recognized P. alaskense 

in several middle and late Pliocene formations in Japan. 

He also suggested that Polynemamussium simanense 

(Kuroda), a Recent species from Shimane Prefecture, 

Japan, may be a subspecies of P. alaskense.

Pecten (Propeamusium) river si Arnold (1906, p. 126, 

pi. 44, figs. 8, 9), early Pleistocene from Deadman 

Island, near San Pedro, Los Angeles County, Calif., is 

closely related to P. alaskense; according to Arnold's 

figures the internal riblets are weaker and more closely 

restricted to the marginal area, and the external riblets 

of the left valve are stronger.
SYSTEMATIC PALEONTOLOGY

The earliest known American species of Polynemamussiwn is Pecten (Propeamusium) levis Moody (1916, 

p. 56, pi. 2, figs. 2a-d) (renamed Pecten calamitus 

Hanna, 1924, p. 176) from the Fernando Formation 

(late Pliocene) of Los Angeles. As noted by Moody, 

the internal riblets of Polynemamussium calamitus are 

more like those of P. dlaskense than those of P. riversi. 

P. alaskense has been reported from Pleistocene beds in 

the Vancouver area (Wagner, 1959) and Alaska (Dall, 

1898, p. 711). Kegardless of the way in which the 

synonymy of this compact group may be resolved ultimately, its known distribution suggests that it is a 

migrant from East Asia.

Types: The holotype, in the U.S. National Museum, is from 

Port Etches, western Hinchinbrook Island, Prince William 

Sound, Alaska. It measures 19.5 mm in both height and length. 

Figured specimens, USNM 644867-644869.

Locality of figured specimens: Postglacial deposits in the 

vicinity of Juneau, Alaska, USGS M212, M218, M243.

Occurrence: According to Masuda, this species occurs in early 

Pliocene to Recent deposits in Japan, in Pleistocene (and postglacial) beds of southeastern Alaska and the Vancouver area, 

British Columbia, and is living from Bering Sea to Panama. 

Grau gave Lower California as the southern limit. Other specimens in the U.S. Geological Survey collections are from early 

Pleistocene beds on Middleton Island, Alaska, USGS 17744, and 

postglacial beds near Juneau, Alaska, USGS 5256, 12066.

Polynemamussium davidsoni (Dall)

Plate 5, figure 7

Pecten davidsoni Dall, 1897, Nautilus, v. 11, no. 8, p. 86.

Dall, 1902, U.S. Natl. Museum Proc., v. 24, p. 559, pi. 45,

figs. 5, 6. 

Pecten (Pseudamusium) davidsoni, Arnold, 1906, U.S. Geol.

Survey Prof. Paper 47, p. 138, pi. 50, figs. 4, 4a. 

Propeamussium (Parvamussium) davidsoni, Grau, 1959, Allan

Hancock Pacific Exped., v. 23, p. 20, pi. 4 (with extended

synonymy).

Discussion. If Grau (1959, p. 21) was correct in 

believing that the presence or absence of radial riblets 

on the right valve of this species is a matter of individual variation, such variation is unusually extreme. 

It would be difficult, furthermore, to assign a given 

right valve to either P. davidsoni or P. alaskense. Both 

Dall's and Arnold's figures show moderately strong 

irregularly spaced radial riblets on the lower part of 

the disc of the right valve, whereas Grau's figure shows 

the right valve to have concentric sculpture only. The 

left valve has moderately strong well-beaded riblets extending nearly to the beak and one or two interstitial 

riblets in the interspaces.

This species has not been reported previously as a 

fossil. A closely related species that differs mainly by 

having stronger and more coarsely beaded riblets on its 

left valve was described by Masuda (1962b, p. 156, pi. 

18, figs. 9a, b, lOa, b, 11) as Polynemamussium yasudae;

it occurs in the Oido Formation (early Miocene) of 

Miyagi Prefecture, northern Honshu, Japan.

Pecten (Propeamusium} clallamensis Arnold (1906, 

p. 57, pi. 3, figs. 1, 3, 3a; not fig. 2), probably from the 

Blakeley Formation of Weaver (1912) (late Oligocene 

and early Miocene), northwestern Washington, may be 

related to this species. It has similar radial rows of 

short curved scales, but they are not situated on raised 

ribs; there are no interstitial riblets. The right valve 

has no radial markings on the disc, but the ears have 

weak radial lirations. Arnold's figure 2 probably is the 

internal mold of his Pecten (Propeamusium) waylandi 

from the same locality.

Types: The holotype (USNM 107747) is from Davidson 

Bank north? of the entrance to Unimak Pass in the eastern 

Aleutian Islands, Alaska. Both the height and length measure 

14 mm. Figured specimen, USNM 644870.

Locality of figured specimen: Postglacial deposits in the 

vicinity of Juneau, Alaska, USGS M243.

Occurrence: Dall (1902) reported that the species lives in 

Bering Sea, the Aleutian Islands, and eastward to Kodiak 

Island, Alaska; however, he later reported the locale to be 

(1921) only Davidson and Bowers Banks, Bering Sea. The 

fossil from near Juneau is well outside of its known Recent 

geographical range. Polynemamussium davidsoni also occurs 

in postglacial deposits near Juneau at USGS 5256.

Genus AKCTINTJLA Thiele, 1935

Propeamusium (Palliolum (Arctinula)) Thiele, 1935, Handbuch der systematischen Weichtierkunde, p. 806.

Type species (by monotypy) : Pecten greenlandicus 

Sowerby/ (= Arctinula groenlandica ( Sowerby)). Kecent. Greenland westward to Dolphin and Union 

Strait and southward to the Gulf of Saint Lawrence; 

Arctic except for the Beaufort and Chukchi Seas; Norway southward to northern Africa.

Discussion. Arctinula, which was proposed as a section of the subgenus Palliolum, was raised to the rank 

of genus by Soot-Kyen (1958, p. 12), and it is here so 

regarded. The type species has been referred to the 

genus Palliolum by most modern authors.

Crosse (1885, p. 140) designated Pecten incomparabilis Kisso as the type species of Palliolum Monterosato. If Koger's (1939, pi. 21, fig. 2a) figure of Pecten 

incomparabilis is correct, Palliolum has a sharp byssal 

notch and Gamptonectes-\\k& sculpture, characters very 

unlike those of Arctinula groenlandica (Sowerby). 

Stewart (1930, p. 118) made his Delectopecten a subgenus of Palliolum and stated that the type species of 

Delectopecten, Pecten (Pseudamusium) vancouverensis, 

has a weak Oamptonectes-like microsculpture. Although he commented on the detached ear of P. incomparabilis, he did not mention its microsculpture.

Grau (1959, p. 57) concluded that Palliolum is a 

synonym of Pseudamussium. Even accepting, as did
CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Grau, the extremely tenuous reasoning of North (1951, 

p. 231) in determining the type species of Pseudamussium as Ostrea hyl>rida Gmelin, I am not convinced that 

it represents the same group as PaUiolum; the type has 

since been determined as Pecten septemradiatus Miiller.

Grau (1959, p. 53, pi. 20) further concluded that 

' ''Pecten greenlandicus'1 '' is a Delectopecten; he treats the 

species as Cyclopecten (Delectopecten) groenlandica 

( Sowerby). His photograph is probably the best figure 

of the species available. I cannot agree that Arctinula 

groenlandica is a Delectopecten, nor can I see any relationship between A. groenlandica and Palliolum, 

whatever the final deposition of that genus may be.

Despite its wide Arctic and Atlantic distribution, 

Arctinula groenlandica appears never to have gained 

access to Bering Sea or the northern Pacific Ocean.

Arctinula groenlandica (Sowerby) 

Plate 4, figure 6

Pecten greenlandicus Sowerby, 1842, Thesaurus Conchyliorum,

v. 1, p. 57, pi. 13, fig. 40. 

Palliolum (Arctinula) groenlandicum, Thiele, 1935, Handbuch

der systematischen Weichtierkunde, p. 806. 

Palliolum ffroenlandicum, MacNeil, 1957, U.S. Geol. Survey Prof.

Paper 294-C, p. 104, pi. 11, figs. 17,18. 

Arctinula groenlandica, Soot-Ryen, 1958, Norsk Polarinstitutt

Skrifter, no. 113, p. 12. 

Cyclopecten (Delectopecten) greenlandicus, Grau, 1959, Allan

Hancock Pacific Exped., v. 23, p. 53, pi. 20 (with extended

synonymy).

Discussion. Until Grau argued for a return to the 

original spelling, no author since Sowerby has spelled 

the name greenlandicus. Most authors have spelled it 

oe, and a few 0 or 6.

Grau's excellent photographs of the species show 

clearly the smooth rounded anterior ear of the right 

valve and the very shallow byssal notch. Except for 

some faint radial striations and growth lines, both valves 

are smooth.

In all probability Pseudamusium andersoni Dall 

(1919, p. 19a, figs. 7,8) (renamed P. ~binominatus Hanna, 

1924, p. 175), Eecent, from Dolphin and Union Strait, 

northern Canada, is a synonym. Ellis (1960, p. 39) 

reported A. groenlandica from Eclipse Sound in northern Baffin Island. Soot-Eyen (1932) said that the species lives along the Arctic coast from Norway to the 

East Siberian Sea but that it does not live in the Chukchi 

Sea or the Beaufort Sea.

The Alaskan beds containing A. groenlandica are the 

oldest marine Tertiary deposits in the Arctic Ocean area 

except for beds of approximately the same age in Spitsbergen. I have argued elsewhere (MacNeil, 1965) that 

these beds represent the first Tertiary marine invasion 

of the Arctic region and that the predominantly Atlantic affinities of the mollusks indicate that the first connection was with the Atlantic Ocean. Although many 

Pacific mollusks have escaped from the northern Pacific 

to the Arctic, and thence to the Atlantic, very few Atlantic species have entered the Pacific. Pacific to Atlantic migrations seem to have occurred periodically 

since late Miocene time but there is no evidence of migration during any earlier part of Tertiary time. The occurrence of A. groenlandica in Arctic Alaska may antedate the opening of Bering Strait. The species has not 

been found in any subsequent deposits on the Alaskan 

Arctic coast, and recent collecting has failed to reveal it 

living in the Beaufort and Chukchi Seas. If this species is ever found south of Bering Strait, it will have 

considerable stratigraphic significance.

Types: The whereabouts of the holotype is unknown. Grau's 

figured specimen measures 24 mm in height and 25 mm in 

length, probably about the maximum size. The figured specimen from the Nuwok Formation is numbered USNM 561876.

Locality of figured specimens: Lower part of the Nuwok Formation of Dall (1919) (horizon probably middle or upper Miocene), Carter Greek, a stream flowing into Camden Bay, northeastern Alaska, USGS D50 (T).

Genus CHLAMYS Roeding, 1798

Chlamys Roeding, 1798, Museum Boltenianum, p. 161

Type species (by subsequent designation, Herrmannsen, 1846) : Pecten islandicus Miiller. Eecent. North 

Atlantic from Norway to Iceland, Greenland, and south 

to Cape Cod; Arctic Ocean between Greenland and the 

Laptev Sea. Not living in the Pacific.

Discussion. Species included in the genus Chlamys 

are so similar morphologically that little division of the 

genus has been attempted. The genus contains, nevertheless, a very large number of species groups that appear to represent distinct phylogenetic lines. Many of 

the species groups have sculptural or other minor pecularities that distinguish them. Ordinarily such characters are considered to be of specific rather than generic 

importance. In my opinion, however, Chlamys is one of 

the largest and most complex groups of mollusks, and 

it is not made less so by a lack of morphic types. I 

have no doubt that it will be divided eventually into 

several genera and subgenera on sound phylogenetic 

but relatively minor morphological grounds. While it 

is difficult to distinguish such groups in descriptive 

terms, trends in sculptural development are discernible. 

A certain amount of sculptural homeomorphy exists in 

Chlamys, but the value of sculpture cannot be minimized on that account. A well-defined phylogenetic 

series has as much validity in classification and as much 

value in stratigraphic work as a morphological oddity 

to which only a few known specimens can be assigned.
SYSTEMATIC PALEONTOLOGY 9

Subgenus LEOCHLAMYS MacNeil, n. subgen.

Type species: Chlamys (Leochlamys} tugidakensis 

MacNeil, n. sp. Pliocene. Alaska.

Description. Shell of medium to moderately large 

size; moderately inflated, right valve more inflated than 

left valve; elongate dorsoventrally. Ears moderately 

large; recessed, the dorsal slope wider on left valve, 

anterior ear of right valve elongate and narrow, byssal 

sinus wide and deep with a moderately strong ctenolium. 

Ribs strong on both valves, interstitial ribs; present 

or absent; weakly to very strongly scabrous; many 

ribs have thick curved spines. Microsculpture reticulate 

or metal lathelike in juveniles, particularly on left 

valves, but consisting of fine continuous closely set 

raised lirations with a fanlike pattern in adults. Provinculum broad and gaping, extending nearly to the 

end of the ears; crurae moderately strong and weakly 

inclined. Muscle scars and umbonal callus inconspicuous.

Discussion. The most distinguishing characters of 

Leoclilamys are its long anterior ear, its deep, broad 

byssal notch, and its coarse, usually spiny ribs.

This subgenus is named in honor of Dr. Leo G. 

Hertlein, of the California Academy of Sciences, in 

recognition of his many contributions to the study of 

the Pectinidae.

Pectinids with deep, broad byssal notches and elongate or moderately elongate ears are known at least as 

early as Jurassic time. Such species as Chlamys 

splendens (Dollfus) (Arkell, 1931, pi. 10, figs. 1-5) and 

C. nattheimensis de Loriol (ibid., figs. 6-8) from the 

Jurassic, and C. elongatus (Lamarck) (Woods, 1902, 

pi. 32, figs. 1-3) from the Cretaceous resemble C. (Leochlamys} more closely in both auricular and sculptural 

characters than do the true Chlamys of the late Tertiary 

and Recent. These Leochlamys-like forms may prove 

to be the more archaic type of Chlamys.

Chlamys morphologically similar to the subgenus 

Leochlamys are known in the Atlantic-Mediterranean 

region throughout Miocene time. These include such 

forms as C. multistriata and C. m. nimia (Combaluzier, 

1932, pi. 9, figs. 1-4) from the Burdigalian and Tortonian of Basse-Provence, France; C. gloriamaris eggenbwrgensis and C. tauroperstriata alternicostata 

(Schaffer, 1910, pi. 14) from the Burdigalian of the 

Vienna Basin; and both C. justiana and C. varia 

(Eoger, 1939, pi. 22, figs. 19-23) from the Burdigalian 

to Calabrian beds in southern Europe.

Somewhat related Pacific species include Pecten 

columbiana Clark and Arnold (1923, pi. 23) from the 

Sooke Formation (early Miocene?) of Vancouver 

Island, and Chlamys araJcawai (Nomura) (Masuda, 

1954, pi. 19) from early and middle Miocene beds of

223-848 0 67 2

Japan. Three Pliocene species are known from East 

Asia, C. daishdkensis Masuda and Sawada (1961, p. 23, 

pi. 4, figs. 8, 9) and C. iwakiana (Yokoyama) from 

Japan, and Pecten (Chlamys} tanassevitschi Khomenko (see Slodkewitsch, 1938, pi. 20, fig. 5; pi. 21; pi. 22, 

fig. 1) from Sakahalin. C. nipponensis Kuroda and 

several related species (see Masuda, 1962b, p. 181) still 

live in Japan. The group is represented in the upper 

Mekran beds (Pliocene) of West Pakistan by Pecten 

(Chlamys} alexandri Vredenburg. Fleming (1948, p. 

77, pi. 7, figs. 1-3) described a Eecent species from New 

Zealand, Chlamys suprasilis crespusculi, that probably 

belongs to the same group, although the type is a juvenile shell.

At least two other Pacific groups have been recognized that appear i^o be more closely related to C. (Leochlamys) than to C. (Chlamys}. One of these, Scaeochlamys Iredale (1929, p. 162), is based on Pecten lividus 

Lamarck (see Kiister and Kobelt, 1888, pi. 52, figs. 1, 2) 

from Amboina, Indonesia, and it probably should also 

include C. tegula (Wood) and C. squamata (Gmelin). 

In my opinion the latter species does not belong in Mirapecten Ball, Bartsch, and Rehder (1938, p. 84; type M. 

thaanumi Dall, Bartsch, and Rehder, Recent from 

Hawaii), to which it was assigned by Kira (1955, p. 99). 

The other group, Mimachlamys Iredale (1929, p. 162) 

is based on Pecten asperrimus Lamarck from Australia. 

It probably includes C. satoi (Yokoyama) from the 

Byoritzu beds (Pliocene) of Formosa and the equivalent Naha Limestone of Okinawa.

Such a distribution for these supposedly Leochlamyslike forms, combined with their antiquity, might make 

it difficult to determine whether or not C. (Leochlamys} participated in any of the late Tertiary to Recent 

f aunal migrations across the Arctic. The type species, 

C. (L.) tugidakensis, appears to be more closely related 

to a species occurring in the English Crags than to any 

known older Pacific species.

The apparent relative of C. (L.) tugidakensis in both 

the Coralline Crag (Pliocene) and the Red Crag (Pleistocene) of England was identified by Wood (1851, p. 33, 

pi. 6, figs. 4a-c) as Pecten pusio Pennant. According 

to Wood, the Crag species shows no evidence of attachment, but the Recent representatives of P. pusio attach 

themselves to rocks and stones by means of their spines. 

The latter description may be an allusion to C. sinuosa 

(Gmelin), a species included in P. pusio by several 

authors. Nyst (1878, pi. 16, figs, la-j), on the other 

hand, used the name P. pusio for a similar but more 

finely sculptured form from the Scaldesian of Belgium, 

which species Glibert (1957, p. 26) reidentified as G. 

multistriata (Poli).
10 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Altena (1937, p. 60; see Heering, 1950, p. 43) proposed the name Chlamys harmeri to include both the 

Coralline Crag-Eed Crag and Scaldesian forms. Actually G. harnieri is a substitute name for Pecten 

striatus J. Sowerby, non Miiller, so that its type is a 

specimen from the Red Crag at Holy wells near Ipswich, Suffolk. This is a finely ribbed form resembling 

0. multistriata and G. tauroperstriata, and it is not the 

species illustrated by Wood (1851, pi. 6, fig. 4a) as 

Pecten pusio var. striatus or as (ibid. fig. 4b) P. pusio 

var. limatus. The latter species is more closely related 

to G. (L.) tugiddkensis. It may be the species figured by 

Wood (1874, pi. 8, fig. 7) as P. varius* from the Coralline Crag at Pettistree Hall near Sutton, Suffolk.

Despite the similarity of Wood's Pecten pusio to such 

European middle Tertiary species as G. justiana and 

G. varia, the actual succession of these forms has not 

been demonstrated. I am inclined to 'believe, however, 

that P. pusio of Wood and G. (L.) tugiddkensis are 

approximately contemporaneous Atlantic and Pacific 

representatives of the same stock. It remains to be 

shown whether C. (L.) tugiddkensis is a migrant from 

the northern Atlantic or whether the stock is one of 

European origin that reached the northern Pacific by 

way of the Tethys and reentered the northern Atlantic 

in late Pliocene or early Pleistocene time.

It has been shown quite conclusively by Fleming 

(1957) that the Pecten jacobaeus group migrated from 

the Atlantic-Mediterranean region to the AustraliaNew Zealand region in late Tertiary time. There is 

strong reason to believe that this group had a still earlier American origin and that it reached Europe in 

about middle Oligocene time. An undescribed species 

occurs in the Cooper Marl (Oligocene) of South Carolina (MacNeil in Malde, 1959, p. 15, 20) ; it was listed 

as P. n. sp. aff. P. Humphreys! and has not been illustrated. A similar species was described by Von Koenen 

(1868, p. 232, pi. 26, fig. 12) from the Rupelian of Germany as P. rupeliensis. Pecten Jiumphreysi Conrad 

occurs in the Calvert Formation (early Miocene) of 

Maryland, and a similar species, P. borlnquense Hubbard (1920, p. 95, pi. 14, figs. 1, 2), was described from 

the Quebraclillas Limestone (early? Miocene) of Porto 

Rico.

Fleming (1957, p. 16; p. 24, fig. 4), following Grant 

and Gale (1931, p. 222), suggested that the P. jacobaeus 

group is represented in Recent Japanese waters by P. 

aTbicans Schroter (Noda, 1961, pi. 3, figs. 1-4) and that 

the latter represents a branch of the group that reached 

Japan by way of California, where it is represented by 

the Pliocene P. aletes Hertlein (1925, p. 8, pi. 2, figs. 

1, 4). At the time he wrote his paper, Fleming did 

not know, unfortunately, of Pecten (Void] byoritzuensis Nomura (1933, p. 57, pi. 1, figs. 4a, b, 5a, b) from 

the Byoritzu beds (Pliocene) of Formosa. This species 

is much more closely related to P. jacobaeus and to its 

Australian and New Zealand relatives than to P. aTbicans. Since Numora's paper was published, P. byoritzuensis or a subspecies of it has been found to occur 

abundantly in the Naha Limestone (Pliocene) of Okinawa (U.S.G.S. collns., unpub.). The Okinawan Pliocene form is very closely related, in turn, to P. aletes 

Hertlein.

Morris (1952, p. 33, pi. 2) figured a specimen as P. 

diegensis Dall that definitely is not that species (see 

the photograph of the type in Arnold, 1906, pi. 51). 

If this shell came from California, it is a previously 

unrecorded species; it may be an incorrectly labeled 

specimen of P. jacobaeus from the Mediterranean.

As thus reconstructed, it seems likely that both Leochlatnys-\ike» forms and the group of Pecten jacobaeus 

followed migration routes similar to the routes Fleming 

(1957, p. 24, fig. 4J.) postulated for the P. benedictus 

group. Both groups of Pecten migrated from Europe 

to Australia and New Zealand, as well as northward 

along the eastern Asiatic coast, and both seem to have 

crossed the equatorial Pacific to the American west coast. 

While the P. jacobaem group seems to have accomplished its migration in Pliocene time, Leochlamys-likQ 

forms probably reached East Asia earlier. Whereas 

Pecten was confined to warm seas, Leochlamys-like, 

forms invaded temperate and cool seas. A northern 

Pacific representative may have made a trans-Arctic 

migration to Europe in Pliocene time.

Chlamys (Leochlamys) tugidakensis MacMeil, n. sp. 

Plate 7, figures 1-11; plate 8, figure 1

Description. Shell of medium to moderately large 

size; medium inflated, the right valve more inflated than 

the left valve; dorsoventrally elongate. Anterior ear 

of right valve elongate and narrow; byssal sinus very 

broad and deep, byssal area wide with coarse growth 

lines; posterior ear of moderate size with a nearly vertical, slightly concave posterior margin. Anterior ear 

of left valve large and broad, anterior margin nearly 

vertical and slightly convex; posterior ear smaller with 

a weakly concave posterior margin. Dorsal margins 

weakly concave, dorsal slopes of right valve narrow 

with a shallow cleft, dorsal slopes of left valve broad 

and moderately undercut. Umbonal angle broader in 

young juvenile stage than in intermediate stage, flaring 

weakly again in adults. Ribs in juveniles definitely 

paired on the right valve, single with a well-defined 

interstitial riblet on left valve. Adult ribs more crudely 

paired, some paired ribs of equal size, others very unequal. Interstitial ribs rarely present on the right valve
SYSTEMATIC PALEONTOLOGY 11

of adults; interstitial ribs of left valve nearly as strong 

as primary ribs in adults. Adult ribs of both valves set 

with thick, broad, flattened or curved, irregularly spaced 

spines. Microsculpture consisting of fine raised Ca.mptonectes-like, lines that have a fanlike pattern within 

each interspace and rise along the sides of the adjacent 

ribs; the juvenile stage of the left valve has a reticulate 

or metal lathelike microsculpture. Interior of shell 

weakly corrugated.

Discussion. Except for C. (?£.) columbiana (Clark 

and Arnold) (1923, pi. 23) from the Sooke Formation 

(early Miocene?) of Vancouver Island, British Columbia, no pectinids that have a long ear and a deep byssal 

notch have been described from the American west 

coast. C. ( ?Z.) columbiana has much weaker spines 

on its ribs, and the right valve has fine interstitial riblets. Inasmuch as pectinids of this type are an ancient 

group, there is no assurance that C. (L.} tugiddkensis 

is descended from C. (?Z.) columbiana. Some poorly 

preserved specimens from the lower part of the Yakataga Formation reported by me as Vertipecten sp. indet. 

(MacNeil, 1961, p. 236) may belong to this group, but 

the known specimens are internal molds. Leochlamyslike forms appear to have been in the northwestern Pacific area from early Miocene? through Pliocene time.

Types: The holotype (USNM 644871), a right valve, measures 

height 70 mm, length 60 mm. The paratype (USNM 644872) is 

a left valve. Other figured specimens are numbered USNM 

644873-644881, 645052.

Type locality: Near the center of the northwest side of Tugidak Island, Alaska, 320 ft below the top of a section computed 

to be 3,520 ft thick, 56°31" N., 154°42" W., USGS M1494.

Other occurrences: 1,900 ft above the base of the Tugidak 

Island section, USGS M1895; several horizons in the lower 2,500 

ft of a section estimated to be nearly 4,000 ft thick, Middleton 

Island, Alaska, USGS 17746, M1746, M1751, M1754; upper part 

of Yakataga Formation (horizon probably Pliocene), along 

south side of Deadfall Creek north of La Perouse Glacier, Lituya district, Alaska, USGS M1851; upper part of the Yakataga 

Formation (horizon probably Pliocene) in the Chaix Hills, Malaspina district, Alaska, USGS M1878.

Subgenus SWIFTOPECTEN Hertlein, 1935

Pecten (Swiftopecten) Hertlein, 1935, California Acacl. Sci. 

Proc., 4th ser., v. 21, no. 25, p. 319.

Type species (by original designation) : Pecten swifti 

Bernardi. Kecent. Japan.

Discussion. Swiftopecten is one of the most distinctive subgenera of Chlamys. Masuda (1959a, p. 87) used 

Swiftopecten as a subgenus of Chlamys, as do most recent authors; a few authors still include it under Pecten. 

At that time, Masuda discussed the apparent relationship of Swiftopecten to Chlamys cosibensis (Yokoyama). In 1960, however, Masuda (1960, p. 380) decided that Pecten swifti was related to and probably 

descended from P. notoensis Yokoyama, which species

Hatai and Masuda (1953, p. 76) had earlier made the 

type of a new genus, Nanaochlamys. Inasmuch as 

Swiftopecten was thus presumed to have evolved from 

a group not part of Chlamys, he raised Siviftopecten to 

generic rank, a practice which he continued to follow in 

1962 (Masuda, 1962b, p. 131,195).

While there might be some justification for treating 

Sioiftopecten as a genus because of its morphological 

pecularities, I doubt very much if it is closely related 

to Nanaochlamys notoensis. C. (S.} swifti appears to 

be rather closely related to Pecten (Swiftopecten^.} 

otutumiensis Nomura and Hatai (see Masuda, 1960, pi. 

39, figs. 6-8), from the Otsutsumi Formation (middle 

Miocene) of northern Honshu; but, here again, I can 

see no relationship with N. notoensis; Masuda treated 

this form as a subspecies, Nanaochlamys notoensis 

otutumiensis.

There is a striking similarity between Nanaochlamys 

notoensis and Chlamys (Flexopecten) schafferi 

Kautsky (see Roger, 1939, p. 200, pi. 27, figs. 1,2) from 

the Tortonian of the Vienna Basin. If these two forms 

are related, as they certainly seem to be, either a 

Tethyan origin or the migration of the stock to East 

Asia by a Tethyan route seems most likely.

Nanaochlamys notoensis (Yokoyama) was described 

from the Nanao Formation (early Miocene) nearNanao, 

Ishikawa Prefecture, west-central Honshu. Specimens of the species collected by Dr. Kotora Hatai, and 

Dr. Shoshiro Hanzawa of Tohoku University, and by 

me from the Moniwa Formation (early Miocene), 

Miyagi Prefecture, northeastern Honshu, show the left 

valve to be flat or slightly concave in the juvenile stage. 

This condition suggests a relationship of Nanaochlamys 

with Pecten (Pecten} rather than with Chlamys or 

Swiftopecten.

Chlamys Mtanvurai Kotaka (1955, p. 26, pi. 2, fig. 2; 

Masuda, 1962b, p. 199, pi. 20, fig. 12), from the Isomatsu 

Formation (late Oligocene) of Aomori Prefecture, 

northern Honshu, may well be the earliest known 

Siviftopecten; Masuda treated the species as Nanaochlamys kitamumi.

If some of the forms figured by Masuda (1959b, pi. 

13) as Chlamys cosibensis, or subspecies of it, are not 

related to Swiftopecten, as Masuda seems now to believe, 

they exhibit a remarkable amount of homeomorphy with 

Swiftopecten. The Chlamys cosibensis group may yet 

prove to have diverged from Swiftopecten in Oligocene 

time. The ribbing on juvenile right valves is very similar in Swiftopecten and the group of Chlamys beringiana (compare pi. 20, fig. 1 with Slodkewitsch, 1938, pi. 

23, fig. 3).

Chlamys (Swiftopecten} donmilleri, here described 

from middle Miocene beds of Alaska, is the oldest Amer-
12 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

lean representative of the subgenus yet known. Several 

Pliocene species have been described from California. 

C. (8.} kindlei (Dall) is one of the most abundant species in the Intermediate Beach (middle Pleistocene) at 

Nome, Alaska, but no other American Pleistocene or 

Recent occurrences are known.

The existence of Swiftopecten-like forms in Europe 

poses some further problems of origin, descent, and 

name priority. Manupecten Monterosato, 1889 (type, 

Ostrea pes-felis Linne, Recent, Mediterranean) is remarkably like /Swiftopecten. According to Roger 

(1939, p. 179), G. (M.) pes-felis has been in the Mediterranean from Calabrian (early Pliocene) to Recent time. 

Conceivably, it could be a migrant from the Pacific.

Until more is known of Tertiary migration routes 

and the place of origin of different pectinid stocks, it 

would be unwise to make a decision concerning the synonymy of Manupecten and /Swiftopecten. To do so 

might obscure some very important morphic and phylogenetic trends, as well as some important avenues of migration. It is not known to what extent groups of central or southern Pacific origin may have migrated to the 

northern Pacific nor to what extent they may have migrated to Europe by a Caribbean route, and it is not 

known whether any groups migrated westward through 

the Tethys. There is a distinct possibility, however, that 

the modern European fauna is a mixture of stocks that 

originated in European waters and remained there 

throughout Tertiary time and of representatives of the 

same stocks that migrated to East Asia via a Tethyan 

route and back to Europe in late Tertiary or Quaternary time via an Arctic route. Other species of undoubted European origin lived in the extreme northern 

Pacific region from late Miocene to Recent time. Some 

such groups undoubtedly reached the Pacific by way of 

the Arctic.

Chlamys (Swiftopecten) donmilleri MacNeil, n. sp. 

Plate 3, figures 1, 4, 6

Description. Shell of medium size, moderately inflated ; hinge of medium length; umbonal angle moderately narrow in juveniles but flaring strongly in adults; 

shell weakly asymetrical anteroposteriorly, strongly plicate and strongly varicate. Anterior ear of right valve 

moderately long, byssal area narrow, byssal notch moderately shallow; posterior ear of right valve short with 

a nearly vertical posterior margin. Ears of left valve 

unknown. Right valve has four strong medial plicae 

and an indistinct narrow plication at each end, interspaces about half as wide as plications, deepest between 

the growth varices; secondary sculpture consisting of 

low flattened lirations, 9 or 10 on the plications and

5 to 8 in the interspaces, strongest at the edge and on the 

forward slope of the growth varices. Left valve has 

five moderately strong plicae and wider interspaces that 

are more deeply sunken between the varices; secondary 

sculpture consists of raised lirations that tend to be 

weakest midway between the varices, although the crest 

of some varices may be nearly smooth. Interior features not known.

Discussion. This species and the following doubtfully identified forms from the Alaska Peninsula are the 

oldest Swiftopecten to be recorded from America. 0. 

(8.) donmilleri occurs in the part of the Yakataga Formation believed to be of middle and late Miocene age, 

and the Alaska Peninsula forms occur in association 

with Mytilus middendorffi Grewingk, believed to be a 

reliable indicator for the middle Miocene.

A Swiftopecten of comparable age and probably 

closely related to 0. (/S.) donmilleri wT as figured by 

Masuda (1959a, pi. 9, fig. 1) as 0. (S.}swifti. It comes 

from the Otsutsumi Formation (middle Miocene; late 

early Miocene in a twofold division) of Miyagi Prefecture, northern Honshu. A right valve from the same 

locality was figured by Nomura and Hatai (1937, pi. 18, 

fig. 6).

Nomura and Hatai (1937, p. 130, pi. 18, fig. 7 (described another species from the Otsutsumi Formation 

as Pecten (Swiftopecten ?} otutumiensis, Masuda 

(1960, pi. 39, fig. 8) figured another specimen from the 

same locality as Nanaochlamys notoensis otutumiensis. 

Whether or not this form proves to be a variant of the 

form assigned to C. (S.} sivifti remains to be seen, but I 

doubt if it has any relationship to NanaocJilamys notoensis. Masuda (1960, pi. 39, figs. 6, 7) also figured two 

specimens from the Suenomatsuyama Formation (middle and late Miocene according to Masuda; late Miocene 

and early Pliocene according to Hatai and Nisiyama, 

1952, p. 14) as N. notoensis otutumiensis. These are 

definitely a Swiftopecten, in my opinion, and the left 

valve strongly resembles a fragment figured here (pi. 3, 

fig. 2) from middle Miocene beds at Port Moller, Alaska 

Peninsula.

Types: The holotype (USNM 644882), a right valve, measures 

69 mm in height and 64 mm in length. The paratype (USNM 

644883) and a figured specimen (USNM 644884) are incomplete 

left valves.

Type locality: 1,500 ft above base of Yakataga Formation 

(horizon probably middle Miocene), south side of White River 

near foot of glacier, Yakataga district, Alaska, USGS 6694.

Other occurrences: Near base of Yakataga Formation (horizon probably middle Miocene), unnamed creek north of and 

parallel to Yakataga Ridge, Yakataga district, Alaska, USGS 

15437; near base of Chaix Hills section of Yakataga Formation 

(horizon probably upper Miocene), south flank of Chaix Hills 

near margin of Malaspina Glacier, USGS 17817.
SYSTEMATIC PALEONTOLOGY 13

Chlamys (Swiftopecten) cf. C. (S.) donmilleri MacNeil 

Plate 3, figure 3

Discussion. A specimen collected by the Shell Oil 

Co. from the northwest side of Cape Aliaksin, Alaska 

Peninsula, differs from the holotype of C. (S.} donmilleri by having stronger and more continuous secondary 

riblets on its primary plicae; the plicae are broader and 

the interspaces correspondingly narrower. Whether or 

not this is a matter of individual variation is not, certain 

on the basis of the few specimens at hand.

The only other fossil found with this specimen was a 

small barnacle, but other collections of similar lithology 

from the same region have yielded Mytilus middendorffi. The specimen is believed to be from the basal 

part of the Unga Conglomerate (horizon probably basal 

middle Miocene).

Figured specimen: (USNM 644885), consists of two fragments 

presumably of the same right valve. It has a height of 

approximately 62 mm.

Locality of figured specimen: Greenish gravelly sandstone, east 

side of Beaver Bay and along the southwest-northeast-trending 

coast at the northwest corner of Oape Aliaksin, Alaska Peninsula, 

USGS M2132.

Chlamys (Swiftopecten) sp. 

Plate 3, figure 2

Discussion. The mold of an incomplete left valve is 

present in a collection from the east side of Port Moller. It is associated with numerous specimens of Mytilus middendorffi, Pododesmus (Monia) sp., Spisulal, 

Tellina, and Cry fanatical, and presumably it comes 

from the lower part of the Unga conglomerate (middle 

Miocene).

The specimen has small, widely spaced radial plicae 

and numerous interstitial riblets. It compares most 

closely with a left valve figured by Masuda (1960, pi. 

39, fig. 7) as Nanaochlamys notoensis otutumiensis.

Figured specimen: USNM 644886, a rubber cast of a fragment of a left valve, measures 41 mm in its longest dimension. 

Locality of figured specimen: USGS 5046.

Chlamys (Swiftopecten) swifti kindlei (Ball)

Plate 3, figures 5, 7-9

Pecten (Chlamys) kindlei Ball, 1920, U. S. Geol. Survey Prof.

Paper 125-C, p. 30, pi. 6, figs. 2, 7. 

Pecten (Pallium) swifti kindlei, Grant and Gale, 1931, San

Diego 'Soc. Nat. History Mem., v. 1, p. 174, pi. 10, fig. 7. 

Pecten (Hanupecten) kindlei, MacNeil in MaeNeil, Mertie, and

Pilsbry, 1943, Jour. Palentology, v. 17, no. 1, p. 87, pi. 12,

figs. 7, 8. 

Chlamys (Swiftopecten) swifti kindlei, Masoida, 1959, Trans.

Proc. Paleant. Soc. Japan, new ser., no. 34, p. 93. 

Chlamys (Swiftopecten) kindlei, MacNeil in Hopkins, MacNeil,

and Leopold, 1960, 21st Internat. Geol. Cong. Proc., pt. 4,

p. 50.

Swiftopecten swifti kindlei, Masuda, 1962, Tohoku Univ. Sci. 

Repts., 2d ser. (Geology), v. 33, no. 2, p. 196.

Discussion. Chlamys (Swiftopecten} swifti is certainly the closest known relative of this Alaskan form, 

regardless of whether they are considered one or separate species. C. (/S.) swifti Mndlei is less inflated than 

typical C. (/S.) swifti, the plicae are less raised, and there 

is very little tendency for the shell to develop varices 

and nodes. From the stratigraphic and migrational 

standpoint, it probably is desirable for the nomenclature 

to emphasize the similarities rather than the differences.

The Mediterranean species, C. (Manupecten) pesfelis, has a narrower umbonal angle, narrower and 

higher plicae, and finer secondary riblets. In addition, 

it has a row of rounded nodes along the dorsal margin 

of both ears.

I am inclined to believe that C. (/S.) kindlei is a Pleistocene offshoot from the typical C. (S.) swifti of Japan 

rather than a descendant of the Alaskan Miocene C. 

(S.) donmilleri or any of the California Pliocene species. G. (/S.) kindlei is one of the most abundant species in the Intermediate Beach at Nome, and it certainly 

is the most conspicuous fossil. Unless it was brought 

to Nome from East Asia in a single pelagic transportation, it may yet be found elsewhere in an intervening 

area, possibly the Aleutians. Slodkewitsch (1938, p. 

108) reports #. (/S.) swifti from the Pomyr Series (late 

Pliocene?) of Sakhalin, and (ibid., p. 109) C. (S.) 

swifti piltukensis (Khomenko), a very weakly plicated 

form, from both the Pomyr Series of Sakahalin and the 

Upper Kavran Series (late Pliocene?) of Kamchatka. 

Merklin, Petrov, and Amitrov (1962), however, do not 

report /Swiftopecten from any Pleistocene beds in the 

Chukotsk Peninsula. There is no evidence at present, 

therefore, that Swiftopecten reached Alaska by way of 

Chukotsk, the closest Asiatic region geographically.

Types : The specimens figured by Dall are designated the lectotype (right valve) and lectoparatype (left valve), respectively; 

both are numbered USNM 324301. The largest specimen figured here (USNM 644887), a right valve, measures height 115 

mm, length 97 mm. A smaller left valve is numbered USNM 

644888; two left-valve fragments are numbered USNM 644889, 

644890.

Type locality: Intermediate Beach (middle Pleistocene), 

Nome, Alaska, USGS 7619? This may be USGS 5074 incorrectly 

numbered; at any rate, the species has been found only in the 

Intermediate Beach.

Other occurrences: Intermediate Beach, USGS 4537, 4538, 

5313, 14866, M333, M1084. M1252.

Submenus CHLAMYS Roeding

Discussion. The species here treated as Chlamys 

("Chlamys") belong to the large Jurassic to Eecent 

group generally referred to the genus Chlamys, but not 

to the typical subgenus which consists of exclusively
14 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

northern Atlantic and northern Pacific species closely 

related to Pecten islandicus Miiller. As thus restricted, 

typical Chlamys (Chlamys} ranges from late Miocene 

to Recent. Even as here treated the subgenus may be 

found ultimately to be polyphyletic. The C. islandica 

and C. beringiana groups may be found to be coordinate 

in rank and derived from different species of a still 

unnamed ancestral subgenus of Chlamys. Until much 

more is known of the actual phylogeny of these groups, 

it is probably best to combine them.

Group of C. ("C.") hastata (Sowerby)

Chlamys ("Chlamys") hastata (Sowerby)

Plate 24, figures 7, 10

Pecten hastatus Sowerby, 1843, Thesaurus Conchyliorum, v. 1, 

p. 72, pi. 20, fig. 236.

Pecten (Chlamys) hastatus, Arnold, 1906, U.S. Geol. Survey 

Prof. Paper 47, p. 108, pi. 42, figs. 1, la, 2, 2a (with extended synonomy).

Chlamys hastata, Grau, 1959, Allan Hancock Pacific Exped., 

v. 23, p. 84, pis. 27, 28 (with extended synonomy).

Discussion. Of the species here doubtfully referred 

to the subgenus Chlamys (Chlamys), Pecten hastatus 

Sowerby is probably the species most distantly related 

to the type species, C. (C.) islandica. It certainly falls 

within the genus Chlamys as construed by most authors 

and it probably shares with Chlamys (Chlamys) an 

ancestry in some Tertiary Leochlamys-like form; that 

is, both are derived from the more primitive type of 

Chlamys, which has a moderately high shell, a long 

anterior right ear, and a broad byssal notch.

Arnold (1906, pi. 11, fig. 4) figured a specimen from 

beds of late Pliocene or early Pleistocene age near San 

Pedro, Calif., as Pecten (Chlamys} Jiastatus. This 

specimen has broader scales on its ribs than the Recent 

C. hastata, and the drawing does not show the fine interstitial riblets. A more typical specimen of C. hastata 

(as Pecten (Pecten) hastatus} was figured by Grant 

and Gale (1931, pi. 11, figs. 6a, b) from supposed early 

Pleistocene beds in Ventura County, Calif.

One possible relationship of C. hastata is suggested by 

the similarity of the long ear, the broad byssal notch, 

and the juvenile sculpture to the corresponding parts of 

C. (Leochlamys} tugidakensis (compare Arnold's 

figures of C. hastata (1906, pi. 42, figs. 1, la, 2, 2a) with 

C. (L.) tugidakensis (pi. 7)). A very definite pairing 

of the ribs on juvenile right valves is apparent in both 

species. If C. hastata should prove to be derived from 

some Miocene representative of Leochlamys, it would, of 

course, have no close relationship to any of the other 

northern Pacific Chlamys (Chlamys} here discussed.

Grau (1959, p. 90) regarded C. pugetensis (Oldroyd) 

as a subspecies of C. hastata. Both of these species are 

equally remote from C. Islandica. These forms are undoubtedly related, but I am inclined to regard them us 

separate species. C. pugetensis has a superficial resemblance to C. multistriata (see Sacco, 1897, pi. 1, figs. 

12-19), a member of a group known throughout the 

middle and late Tertiary of southern Europe.

C. hastata is probably indigenous to the Pacific. An 

apparently undescribed species from the Pancho Rico 

Formation (early Pliocene) northeast of King City, 

Monterey County, Calif., UC A906, has a broad 'byssal 

notch and sculpture resembling that of C. hastata hericius although it is somewhat less scabrous. Juveniles 

of both this undescribed species and C. hastata are 

nearly identical for about the first 10 mm of growth. 

Adults of C. pugetensis, which usually do not exceed 

30 mm in height, also resemble a comparable stage of the 

Pancho Rico species.

The stock of C. hastata may be represented in the Red 

Crag (early Pleistocene) of England by Pecten disparatus Wood (1882, p. 12, pi. 1, fig. 17). Wood was unable 

to find an undoubted relative of this single shell in 

Europe.

Types: The holotype, in the British Museum, is a juvenile 

shell; Sowerby gives its height as 1.15 in. (29 mm). Adults of 

the species average about 65 mm in height. Figured specimens, 

USNM 644891, 644892.

Type locality: Unknown. Grau (1959, p. 85) designated San 

Diego, Calif., as the type locality.

Locality of figured specimens: Santa Barbara County dump 

Foothill Boulevard, about three-fourths mile west of intersection 

with State Highway 150, NW% sec. 11, T. 4 N., R. 28 W., Santa 

Barbara County, Calif. Santa Barbara Formation (horizon 

lower Pleistocene).

Occurretice: Pliocene to Recent in southern California. The 

species now lives from San Diego to Monterey, Oalif.

Chlamys ("Chlamys") hastata hericius (Gould)

Plate 21, figures 1, 3 

Pecten hericius Gould, 1850, Boston Soc. Nat. Hist. Proc., v.

3, p. 345. 

Gould, 1852, U.S. Exploring Exped., v. 12, p. 457, pi. 42,

figs, 570a-c. 

Pecten (Chlamys) liericeus, Dall, 1898, Wagner Free Inst. Sci.

Trans., v. 3, no. 4, p. 708. 

Pecten (Clilamys) hastatus var. hericius, Arnold, 1906, U.S.

Geol. Survey Prof. Paper 47, p. 110, pi. 43, figs. 3, 3a. 

Pecten (Pecten) hastatus, Grant and Gale, 1931, San Diego

Soc. Nat. History Mem., v. 1, p. 166. (In part.) 

Chlamys hastata hericia, Grau, 1959, Allan Hancock Pacific

Exped. v. 23, p. 87, pi. 29 (with extended synonymy). 

Discussion. Typical C. hastata ranges from Monterey to San Diego, Calif., whereas C. hastata hericius 

ranges from the Gulf of Alaska to Santa Barbara, 

Calif. The more extreme variants of typical C. hastata 

have high, sharp crested ribs with moderately large 

spinelike scales, whereas the opposite extreme of C. 

hastata hericius has low bundles 'or fascicles of riblets 

with all the riblets finely and equally scabrous. Some
SYSTEMATIC PALEONTOLOGY 15

intermediate specimens might be difficult to assign to 

either subspecies. If living individuals of these forms 

do not constitute an entirely continuous series of variation, they come very close to it.

The more finely ribbed variants of C. Jiastata hericius 

are believed to be the more archaic form of the species. 

The type of Pecten altiplicatus Conrad (see Arnold, 

1906, pi. -11, fig. 4) from beds of late Pliocene age near 

Santa Barbara, Calif., is closer to the borderline between typical G. hastata and C. hastata hericius. Much 

more will have to be known of the early history of the 

C. hastata group before it can be said with certainty 

that it is related to any known Alaskan or Japanese 

group.

Types: The holotype (USNM 5955) was figured by Gkmld 

(Johnson, 1964, p. 87). Arnold (1906, pi. 43, figs. 3, 3a) figured 

one of the coarsely sculptured variants. Figured specimen 

(GAS 12611), one of the more finely sculptured variants, measures 66 mm in height and 60.5 mm in length.

Type locality: Strait of Juan de Fuca, Wash. The subspecies 

lives from the Gulf of Alaska to Santa Barbara, Calif.

Locality of figured specimen: Puget Sound, CAS loc. 31879.

Chlamys ("Chlamys") pugetensis (Oldroyd) 

Plate 22, figures 4, 5

Pecten islandicus pugetensis Oldroyd, 1920, Nautilus, v. 33, p.

136, pi. 4, figs. 5, 6. 

Pecten (Chlamys) islandicus pugetensis, Dall, 1921, U.S. Natl.

Museum Bull. 112, p. 19. 

Oldroyd, 1924 [1925], Stanford Univ. Pubs., Geol. Ser., v. 1,

no. 1, p. 55, pi. 12, figs. 4, 5. 

Oldroyd, 1924, Puget Sound Biol. Sta. Pubs., v. 4, p. 18,

pi. 9, figs. 5, 6. 

Pecten (Pecten) liastatus var. pugetensis, Grant and Gale, 1931,

San Diego Soc. Natl. History Mem., v. 1, p. 168. 

Chlamys hastata pugetensis, Grau, 1959, Allan Hancock Pacific

Exped., v. 23, p. 90, pi. 10 (with extended synonymy).

Description. Shell small, rarely exceeding 35 mm in 

height. Anterior ears large; anterior ear of right valve 

may be very long and straight; byssal sinus may be well 

rounded or angulate. Anterior dorsal margin usually a 

little longer than posterior dorsal margin. Ribs usually 

show a weak differentiation into primary, secondary, 

and even tertiary series. Eibs of right valve are bluntly 

rounded, but ribs of left valve tend to have a narrow 

rounded crest; small upright scales may be present. 

Primary ribs, and some other ribs, tend to become 

tripartite near the margin by the addition of minor 

riblets or ridges on the sides. The microsculpture is 

reticulate or metal lathelike and usually covers all the 

interspaces. Color is extremely variable. Some specimens have a nearly white right valve and brown radiating bands on the left valve. Other specimens have a 

reddish-orange left valve and a brownish right valve, 

sometimes with purple concentric bands; anterior ear

of the right valve may be pure white. Still other specimens are uniformly reddish orange.

Discussion. This small pectinid is sufficiently distinct to stand as a separate species. Middendorff's 

original figures of C. ~beringiana are reconstructed so 

as to give the impression of relationship to C. pugetensis. I am not aware of the occurrence of C. pugetensis 

in Bering Sea. Grant and Gale (1931, p. 168) and 

Grau (1959, p. 90) associated this form with Pecten 

hastatus and Burch (1944, p. 5) associated it with 

P. hericius. Its closest known relative probably is 

G, hastata hericim, but it diverged from the hastata 

stock in Pliocene time (see remarks under C. hastata, 

p. 14).

Types: The holotype is in the collections of Stanford University. The figured specimens (USNM 637739, 637740) are different individuals; the larger, a left valve, measures 31 mm in 

height and 26 mm in length.

Type locality: Recent, San Juan Island, Puget Sound, Wash.

Distribution: This species was identified from supposed Pliocene beds near Los Angeles (Grant and Gale, 1931, p. 168). It 

was collected by W. O. Addicott, of the U.S. Geological Survey, 

from a terrace deposit of late Pleistocene age about one-half 

mile southeast of Point Ano Nuevo, San Mateo County, Calif. 

The species is fairly abundant in the vicinity of Puget Sound. 

Grau (1959, p. 91) gave its Recent range as Newport Bay (near 

Los Angeles), Calif., to Hinchinbrook Island, Prince William 

Sound, Alaska. The specimen figured here is from Sitkalidak 

Island, USGS M2064, off eastern Kodiak, a further extension of 

its range.

Group of C. ("C.") tauroperstriata Sacco 

Chlamys ("Chlamys") harmeri Altena

Plate 24, figures 4, 6

Pecten striatus J. Sowerby, Mineral Conchology of Great 

Britain, v. 4. pi. 394, figs. 2-4 (non Miiller, 1776).

Pecten substriutus Orbigny, 1852, Prodrome de Paleontologie, 

v. 3, p. 129 (non Roemer, 1835).

Chlamys harmeri Altena, 1937, Bijdrage tot de kennis der 

fossiele, subfossiele en Recente Mollusken, die op de 

Nederlandsche stranden Aanspoelen, en hunner verspreiding, p. 60.

Discussion. Chlamys harmeri is a substitute name 

for the preoccupied Pecten striatus J. Sowerby. I 

am inclined to agree with Altena (written commun., 

Nov. 5, 1964) that this species is not a synonym of C. 

multistriata (Poli), with which it and several related 

forms have been synonymized by several recent 

authors. As pointed out by Altena, G. multistriata is 

a small species, and C. harmeri is probably more 

closely related to C. tauroperstriata Sacco. Glibert 

(1957, p. 26), in one of the latest studies, of the 

species, stated that O. multistriata from the Burdigalian of the Vienna Basin and C. harmeri are of 

comparable size and that the two forms cannot be
16 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

separated on that basis. It would seem, however, 

that the bearing of a middle Miocene form on the relationship of two post-Tertiary forms must certainly 

be contingent on a much more thorough study of this 

group than has been undertaken so far.

This species is the Pecten pusio of Nyst (1878, pi. 

16, figs, la-j), but it is not the Pecten pusio of Wood 

(1851, pi. 6, figs. 4a-c). Probably it is also the G. 

multistriata of Gilbert (1957, p. 26), at least in part. 

According to Dodge (1952, p. 179), Ostrea pusio 

Linne is unidentifiable. He recommended that it be 

accepted as the valid name for Pecten multistriatus 

Poli because it was so used by virtually all writers of 

the last half of the 19th century. He quoted 

Bucquoy, Dautzenberg, and Dollfus, however, as saying that the name should be abandoned.

Types: The holotype of Pecten striatus J. Sowerby is presumably in the British Museum. As a stubstitute name, C. 

harmeri has the same type. Figured specimen (TJSNM 

644895), a right valve, measures 52 mm in height and 47 mm 

in length. The figured left valve is numbered USNM 644896.

Type locality: Holy wells, southeastern outskirts of the 

town of Ipswich, Suffolk. Red Crag (early Pleistocene), 

probably the Newbournian Stage.

Locality of figured specimens: Dredged from the Westerschelde, westernmost Netherlands, USG-S M2519. Probably 

Scaldesian (early Pleistocene).

Chlamys ("Chlamys") breidavikensis MacNeil, n. sp. 

Plate 25, figures 4-8

Description. Shell moderately large, subrounded, 

left valve more inflated than right valve. Anterior 

ear of right valve moderately short and broad, byssal 

notch moderately shallow and V-shaped; posterior 

ear moderately short, posterior margin nearly straight 

and sloping at about 45°. Anterior ear of left valve 

moderately short and broad, anterior margin nearly 

vertical; posterior ear short and steeply sloping. 

Dorsal margins subequal or anterior margin slightly 

straighter and more elongate. Dorsal slopes of left 

valve broader and more undercut than on right valve. 

Kibs moderately fine with only 1 or 2 ribs showing 

any tendency to divide; right valve has about 90 ribs, 

8 to 10 of which are on the dorsal slopes; a few of 

the terminal ribs might be regarded as interstitial 

riblets, but they are nearly as strong as the other 

ribs. Anterior ear of left valve has about 15 fine 

ribs. Ribs low, sculptured only by growth lines. 

Interspaces shallow and bearing reticulate microsculpture on the right valve; left valve interspaces may 

have reticulate microsculpture on early stages but in 

later stages they are smooth or have raised concentric 

lamellae.

Discussion. G. ( u<7.") 'breidavikensis has about 30 

more ribs than O. islandica on half-grown individuals.

Large individuals of G. isldndica may have about 90 

riblets near the ventral margin, but many of the ribs 

divide once or twice to produce that number; very 

few of the ribs of G. breidavikensis bifurcate. Both 

of the posterior ears of G. islandica have a more 

sinuous margin and fewer and coarser ribs.

Both G. breidavikensis and G. tjornesensis have 

been reported in previous lists as G. islandica^ but 

neither is that species, nor am I convinced that either 

is very closely related to G. islandica. In my opinion, 

G. breidafvikensis is more closely related to the group 

of G. multistriata and G. tauroperstriata; typical G. 

islandica is more closely related to early Pleistocene 

forms in the northern Pacific. If an until intermediates are found, however, that definitely link G. 

breidavikensis with some other species, the exact relationships of all these species will remain in doubt.

Types: The holotype (USNM 644897), an incomplete right 

valve, has a length of 72 mm. The paratype (USNM 644898) 

is an incomplete left valve. .Other figured specimens are 

numbered USNM 644899-901.

Type locality: Base of the highest fossiliferous bed in the 

Breidhavik section, beach southwest of lighthouse at Valadalstorfa, Tjornes, northern Iceland (horizon probably early 

glacial Pleistocene), USGS M2153.

Group of C. ("C.") gloriamaris (Dubois)

Chlamys ("Chlamys") tjornesensis MacNeil, n. sp.

Plate 25, figures 1-3

Description. Shell moderately large, subrounded to 

elongate dorsoventrally; left valve more inflated than 

right valve. Anterior ear of right valve large and moderately elongate; byssal notch broad and rounded at 

juncture with dorsal margin; posterior ear unknown. 

Anterior ear of left valve broad, margin nearly vertical 

to sinuous; posterior ear moderately short, margin vertical or slightly inclined. Dorsal margins slightly concave, anterior margin slightly longer. Dorsal slopes of 

left valve moderately broad, posterior slope weakly 

undercut, anterior slope concave but not undercut; anterior ear of right valve nearly flush with edge of disc. 

Ribs of right valve weakly divided into primary, secondary, and tertiary series; primary ribs weakly bifurcating in advanced growth stage, remaining usually as 

a split rib with a moderate median sulcus. Left valve 

tending to have more discrepant primary, secondary, 

and tertiary ribs in juvenile stage; in advanced stage 

the ribs tend to be more uniform and rounded. Ears 

with moderately coarse ribs.

Discussion. The living species most nearly resembling G. tjornesensis probably is C. wainwrigh-tensis from 

Arctic Alaska, The apparent morphological hiatus between G. wamwrightensis and any other Alaskan or 

Pacific species suggests that these forms may indeed be
SYSTEMATIC PALEONTOLOGY 17

related. Inasmuch as nothing is known of possible 

Pleistocene intermediates, however, it is not possible to 

demonstrate the derivation of C. waimvrightensis from 

O. tjornesensis at this time.

A possible antecedent of O. tjornesensis was figured 

by Schaffer (1910, pi. 14, figs. 8, 9) as C. aff. C. longolaevis Sacco. The fragments so figured may be extremely sculptured variants of the species Schaffer 

identified as G. gloriamaris. While C. tjornesensis has 

been identified by several past authors as G. islandica, 

there seems to be no close relationship with that species.

Types: The holotype (USNM 644902), an incomplete right 

valve, measures 85 mm in height. The paratype (USNM 

644903) is an incomplete left valve. Another figured specimen, 

an incomplete left valve, is numbered USNM 644904.

Type locality: Sea cliff south of the mouth of Hallbjarnarstadhaa, Tjdrnes district, northern Iceland, Glycymeris bed of 

the Mactra zone (horizon probably uppermost Pliocene), USGS 

M2203.

Other occurrences: Sea cliff north of the mouth of Hallbjarnarstadhad Tjornes district, northern Iceland, Serripes groenlandicus zone (horizon probably lower Pleistocene), USG-S M2155.

Group of C. ("C.") cosibensis (Yokoyama)

Chlamys ("Chlamys") cf. C. ("C.") cosibensis (Yokoyama)

Plate 11, figures 9,11,12

"iPecten cosibensis Yokoyama, 1911, Geol. Soc. Tokyo Jour., v.

18, no. 208, p. 4, pi. 1, figs. 3, 4. 

IPecten heteroglyptus YoTcoyama, 1926, Tokyo Imp. Univ. Fac.

Sci. Jour., sec. 2, v. 1, pt. 8, p. 304, pi. 33, figs. 1-8.

Discussion. The specimens from Tugidak here compared with Ghlamys (" Ghlamys'''1 } cosibensis are most 

like some of the specimens of C. cosibensis heteroglypta 

figured by Yokoyama (1926) from the Sawane Formation (early Pliocene) at Kaidate-no-sawa, Niigata Prefecture, northwestern Honshu. The right valve (pi. 11, 

fig. 9) has flat-topped but well-defined fascicles resembling those of the specimen in Yokoyaina's plate 33, 

figure 5.

While the Tugidak form may be sufficiently distinct 

to have at least a separate varietal name, the wide range 

of variation shown by the available figures of C. c. 

heteroglypta and G. c. cosibensis appears to include 

variants similar to the form from Tugidak.

Two of the figures of Pecten heteroglyptus in Yokoyama's (1926, pi. 33, figs. 6, 7) original proposal of the 

species were treated as P. heterog7yptu#va.T. cosibensis in 

violation of the priority of cosibensis. He appears to 

have acted on the assumption that heteroglyptus was the 

larger taxon. More recently, Masuda (1959b) placed 

heteroglyptus and P. turpiculus Yokoyama under C. 

cosibensis as subspecies. He also included a new Miocene subspecies, G. cosibensis hanzawae, in addition to 

the typical C. cosibensis cosibensis.

Figured specimens: The largest figured specimen (USNM 

644905), a left valve, has a height of 40 mm and a length of 

34 mm. Other figured specimens are numbered USNM 644906, 

644907.

Locality of figured specimens: Near the center of the northwest side of Tugidak Island, Alaska, 320 ft below the top of a 

section computed to be 3,520 ft thick, 56°30" N, 154°42" W. 

USGS 1494. Horizon probably upper Pliocene.

Chlamys ("Chlamys") coatsi MacNeil, n. sp. 

Plate 14, figures 6, 7; plate 15, figures 1, 2, 5-7

Pecten (Chlamys) beringianus, Stewart and MacNeil in Powers, 

Coats, and Nelson, 1960, U.S. Geol. Survey Bull. 1028-P, 

p. 543.

Description. Shell of medium to moderately large 

size, rotund, moderately inflated. Anterior ear of right 

valve large and broad, byssal area broad; byssal sinus 

moderately broad, moderately deep, and angulate; posterior ear of right valve short, posterior margin sloping 

and weakly concave. Anterior ear of left valve moderately large and broad, anterior margin weakly sinuous. 

Dorsal margins of about equal length, straight or very 

weakly concave. Dorsal slopes moderately broad, those 

of the left valve broader than those of the right valve, 

weakly undercut. Sculpture consisting of broad plicae 

or fascicles centrally and finer riblets near the anterior 

and posterior margins; plicae nearly smooth in juveniles but breaking up into secondary riblets terminally ; 

interplicae with secondary and tertiary riblets that develop earlier than the riblets on the plicae; plicae 

broader than interplicae on right valve, interplicae 

broader than plicae on left valve. Tops of plicae and 

riblets with concentric growth lines only; interspaces 

between riblets with reticulate or metal lathelike microsculpture.

Discussion. The typical form of this species occurs 

with and may intergrade with Ghlamys coatsi middletonensis, here described. Typical G. c. middletonensis 

comes from beds on Middleton Island that are believed 

at present to be older than the beds of Amchitka containing typical G. coatsi. Typical G. coatsi has not been 

found on Middleton Island; the only known occurrence 

of it outside of Amchitka is a single left valve from the 

Gubik Formation near Wainwright, Alaska, supposedly 

from a horizon of about middle Pleistocene age.

G. coatsi may be related through G. c. middletonensis 

to G. pilicaensis Kubota (see Masuda, 1962b, pi. 20, figs. 

1, 2) from the Setana Formation (early Pliocene) of 

Hokkaido. G. pilicaensis has more regular ribs, especially on its right valve, but some specimens of G. c. 

middletonensis approach it in this respect. The more 

coarsely ribbed variants of G. chaixensis are similar to 

G. c. middletonensis, but the range of variation in G. 

chaixensis suggests that it was a stock already divergent 

from G. coatsi in late Pliocene time and that it was pro-
18 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

ducing variants wholly unlike any of the variants of 0. 

coatsi. If O. coatsi is related to C. pilicaensis, as is suspected, it probably is related in turn to 0. chaixensis 

through some early or middle Miocene species such as 

O. otukae. O. otukae is fairly closely related to the 

earliest known member of the C. cosibensis group, 0. c. 

hanzawae, from the early Miocene.

Any attempt to determine the origin of 0. coatsi at 

this time is complicated not only by a time and morphological gap in the Pacific, but also by the abrupt appearance in the Yorktown Formation (late Miocene) of 

Virginia of G. decemnaria (Conrad) (see Gardner, 

1943, pi. 5, figs. 1, 2, 6, 7). I am inclined to doubt the 

descent of 0. decemnaria from Pecten (Chlamys} clintonius Say and P. (O.} clintonius rappahannockensis 

Mansfield, as postulated by Mansfield (1936, p. 184). 

The last two forms belong to the genus Placopecten. I 

believe it likely, however, that 0. decemnaria, Placopecten clintonius, and Myd arenaria, all of which occur in 

the Yorktown Formation, are migrants from the 

Pacific.

C. decemnaria appears to be related to G. coatsi, but 

its long anterior dorsal margin suggests that it may be 

related to O. beringiana. It is older than the earliest 

known Pacific members of either species, and it is 

younger than the possible Japanese early Miocene predecessors 0. otukae and C. cosibensis hanzawae. Although late Miocene representatives of the C. coatsi 

stock have not yet been found in the Pacific region, I 

will suggest that the stock was present then and that it 

migrated to the Atlantic in late Miocene time; it gave 

rise there to C, decemnaria.

Pecten aratus Gmelin, a Kecent deep-water species 

from the northern Atlantic, resembles both C. coatsi 

and C. c. middletonensis. Jensen (1912, pi. 1, figs. 5ad) figured two specimens from south of Iceland at 

depths of 268 and 295 fathoms. His figures 5a and b 

have some ribs nearly as coarse as the large ribs of G. 

coatsi, whereas his figures 5c and d have finer ribs more 

nearly resembling those of the small specimen of G. c. 

middletonensis figured here (pi. 13, fig. 4). Presumably 

Jensen's two specimens represent the opposite extremes 

of variation. The anterior dorsal margin of Jensen's 

specimens is shorter than the posterior margin. In this 

respect, at least, it compares more with some variants 

of G. coatsi and with G. trinitiensis. G. beringiana 

strategics (Oldroyd, 1924b, pi. 41, figs. 1, 2), the only 

broad-ribbed living Pacific form with which it might 

be compared, has a longer anterior dorsal margin. I 

think it likely that G. arata is the only living representative of the G. coatsi stock.

Types: The holotype (USNM 644908), a left valve, has a 

height of 95 mm and a length of 90 mm. The paratype (USNM 

644909), a right valve, measures 70 mm in height, 68 mm in

length. Other figured specimens are numbered USNM 644910- 

644914.

Type locality: Poorly bedded loose sand and gravel forming a 

fill about 75 feet thick at the head of South Bight, Amchitka 

Island, Aleutian Islands, Alaska, USGS D46. Possibly from 

an upper horizon in the section; see discussion under C. 

hanaishicnsis amchitkana (p. 31).

Other occurrences: South Bight, Amchitka Island, USGS 

16908a (paratype) ; Gubik Formation (horizon probably middle 

Pleistocene), mouth of Kuk River near Wainwright, northern 

Alaska, USGS M1828.

Chlamys ("Chlamys") coatsi middletonensis MacNeil, n. subsp. 

Plate 13, figures 3-5, 7; plate 14, figure 8; plate 15, figure 8

Discussion. This subspecies differs from typical C. 

coatsi by having less discrepant juvenile and adult 

sculpture. The plications show less relief in G. c. middletonensis, almost none in some specimens, and the 

secondary riblets on the right valve usually extend to 

the beak; only an occasional plication is smooth. The 

left valve of G. c. middletonensis is more elegantly and 

more precisely sculptured; the ribs are divided into 

primary, secondary, tertiary, and quaternary ribs, the 

finest ribs tending to be neatly beaded towards the 

margins. Specimens from Amchitka show the original 

color; the left valve is bright red, the right valve pale 

pink or white. Typical G. coatsi from the same locality 

is mottled red or has irregular concentric red bands.

The possible relationships of this subspecies were discussed under typical G. coatsi.

Types: The holotype (USNM 644915), an unseparated pair 

of valves, measures 66 mm in height, 59 mm in length. Other 

figured specimens are numbered USNM 644916-644919.

Type locality: From about the top of Miller's measured section (1953, p. 23) on Middleton Island, Alaska, USGS M1741. 

The horizon is about 1,400 ft above the top of the Chlamys 

(Leoclilamys) tugidakensis zone.

Other occurrences: South Bight, Amchitka Island, USGS D46; 

possibly from an upper horizon.

Chlamys ("Chlamys") cf. C. ("C.") coatsi middletonensis MacNeil

Plate 12, figure 4

Discussion. A left valve from the upper part of the 

section on Middleton Island is probably closest to G. 

coatsi middletonensis. The texture and general plan of 

its ribs is intermediate between that subspecies and C. 

pseiidislandica, plafkeri. While it is possible that these 

forms are all part of one intergrading series, it seems 

fairly certain that the end members are foreshadowing 

quite different lines of development.

Figured specimen: USNM 644920, an incomplete left valve, 

lias a height of 72 mm.

Locality of figured specimen: Upper part of ithe section on 

Middleton Island, Alaska, USGS 17745.
SYSTEMATIC PALEONTOLOGY 19

Chlamys ("Chlamys") chaixensis MacNeil, n. sp. 

Plate 9, figures 2, 6-10; plate 10, figures 4, 5, 7, 8

Description, Shell of medium size, suborbicular, 

usually longer than high. Hinge of moderate length. 

Anterior ear of right valve of medium length and 

moderately broad, byssal sinus moderately deep, narrow, and acute; posterior ear of medium length, posterior margin sloping gently and weakly concave. 

Anterior ear of left valve moderately small, margin 

moderately sloping and concave; posterior ear moderately long with a sinuous margin. Umbonal angle 

moderate to large. Dorsal margins nearly straight to 

moderately concave, dorsal slopes narrow and weakly 

undercut. Sculpture variable, ribs ranging from narrow and uniform to moderately 'broad and irregular, 

with or without fascicles; both valves may have moderately broad smooth ribs that divide terminally into> 

several smaller riblets. The interspaces have reticulate 

or metal lathelike microsculpture.

Discussion. This species occurs with and may intergrade with the form (pi. 10, figs. 1-3) identified as 

Ghlamys lioica (Dall). Some unfigured fragments of 

the latter have no radial riblets on either valve. The 

specimens that come closest to connecting these two 

forms are the ones figured on plate 9, figure 8, and plate 

10, figure 1. If these should prove to be one species, 

G. clwixensis could be treated as a variety of subspecies 

of C. lioica, the older name.

Ghlamys cosiben-sis heteroglypta (see Nbmura and 

Hatai, 1935, pi. 11, figs. 1, 2) may be the closest relative 

of this species in the Japanese Pliocene. The only 

other Japanese species that has much resemblance to 

it is G. otukae Masuda and Sawada (1961, pi. 4, figs. 

1-5), described from the Oido Formation (early Miocene) of Miyagi Prefecture, northeastern Honshu. G. 

otukae may be the ancestral stock of G. chaixensis; at 

least I can find no other known Japanese Miocene 

species from which it could be derived.

Some specimens of C. coatsi middletonensis are close 

morphologically to the holotype of C'. chaixensis; the 

latter probably is an extreme variant of the species. 

The general range of variation of the two forms is somewhat different, however; 110 varietal series similar to 

that found at the type locality of G. cliaixensis has been 

found elsewhere in Alaska.

Of the older Alaskan species, C. chaixensis appears 

to be most closely related to some of the forms from the 

middle part of the Tugidak section here referred to G. 

aff. G. trinitiensis (pi. 8, figs. 2-5, 7-9). In all probability C. chaixensis was derived from some part of the 

middle Tugidak assemblage. Possibly the nearly 

smooth ribbed variant shown on plate 8, figure 9, is an

end member of the Tugidak series analogous to the 

more coarsely ribbed variants of G. lioica.

Types : The holotype (USNM 644921), a specimen with paired 

valves, measures 59 mm in height and 60 rnm in length. Two 

paratypes are numbered USNM 644922, 644923. Other figured 

specimens are numbered USNM 644924-644929.

Type locality. Highest part of the section in the Chaix Hills 

(horizon probably upper Pliocene), approximately 6,000 ft above 

a bed containing Chlamys (Leochlamys) tugidakensis. Malaspina district, Alaska, USGS M1875.

Chlamys ("Chlamys") lioica (Dall) 

Plate 10, figures 1-3

Pecten (Chlamys) lioicus Dall, 1907, Am. Jour. Sci., serv. 4, v.

23, p. 457, text fig.

Dall, 1920, U.S. Geol. Survey Prof. Paper 125-C, p. 31. 

Pecten (Pecten) lioicus, Grant and Gale, 1931, San Diego Soc.

Nat. History Mem., v. 1, p. 165. 

Pecten (Chlamys) lioicus, MacNeil, 1943, Jour. Paleontology, v.

17, no. 1, p. 87, pi. 13, fig. 5.

Discussion. Until the discovery of this species in the 

Malaspina district along the northern Gulf of Alaska, 

it was known only from the holotype, a specimen collected from an indeterminate horizon at Nome; no other 

fossils were found with it. Grant and Gale suggested 

that it was merely an abnormal specimen of Pecten islandicus, as that species was interpreted by them.

The suite from the Chaix Hills shows the species to 

have considerable range in variation. One end of the 

series (pi. 10, fig. 1) has narrow but moderately strong 

ribs both anteriorly and posteriorly, and low rounded 

plicae medially. The interspaces have from one to four 

interstitial riblets, and the plicae divide terminally into 

several riblets. This variant approaches the less 

strongly plicated variants of G. chaixensis; additional 

specimens might show that the two forms intergrade. 

The middle part of the series (pi. 10, fig. 3) has a nearly 

smooth central disc. Several incised radial lines occur 

both anteriorly and posteriorly as well as sporadically 

on the central part of the disc. The marginal area of 

adults displays numerous closely spaced riblets of nearly 

equal size. The opposite end of the series has no radial 

sculpture although concentric growth lines and resting 

stages may be moderately strong. The holotype is close 

to the smooth end of the series, having only a few scattered and weakly incised lines close to the margin.

Two specimens from the Coralline Crag (late Pliocene) of England figured by Wood (1851, pi. 5, figs. 2a, 

b) as Pecten tigrinus var. l-aevis and P. tigrinus var. 8 are 

surprisingly like the variants of G. lioica, figured here; 

the former has a smooth disc and marginal riblets, the 

latter has weak plications. P. gerardii (Wood, 1851, 

pi. 5, figs. 5a, b), also from the Coralline Crag, is larger 

and more globose. I collected some fragmental specimens from the Coralline Crag in 1960 that probably are
20 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

P. gemrdii, although one smaller, more inflated individual may be P. tigrinus laevis. All the fragments have a 

delicate diagonal Camptonectes-like microsculpture. 

The juvenile stage of 0. lioica has similar microsculpture, especially near the dorsal margins.

The only nearly smooth Chlamys I find described from 

East Asia is Pecten swifti pUtukensis Khomenko (see 

Slodkewitsch, 1938, p. 109, pi. 29, figs. 1-3) ; it occurs in 

the Pomyr Series of Sakhalin and the upper horizon of 

the Kavran Series of Kamchatka, both late Pliocene. 

While the plications and riblets of this form are subdued, they are present over the entire disc. In all probability this is a Swiftopecten and not very closely related 

to 0. lioica.

Types: The holotype (USNM 110480), a right valve, measures 

61 mm in height, 57 mm in width. The largest figured specimen 

(USNM 644930) is 68 mm high and 69 mm long. Two other 

figured specimens are numbered USNM 644931, 644932.

Type locality: "gravels under tundra near Nome, Alaska, at a 

depth of 50 feet," exact location and beach horizon unknown, 

USGS 4537.

Other occurrences: Highest part of the section in the Ghaix 

Hills (horizon probably upper Pliocene), approximately 6,000 ft 

above a bed containing Chlamys (Leochlamys) tugidakensis, 

Malaspina district, Alaska, USGS M1875.

Chlamys ("Chlamys") trinitiensis MacNeil, n. sp. 

Plate 8. figures 6, 10-12

Description. Shell medium small, inflated, strongly 

plicate, gerontic stage tending to be less plicate and 

more inflated. Anterior ear of right valve moderately 

large and broad, terminal border rounded, byssal area 

of medium width, byssal sinus moderately shallow and 

angulate, ctenolium well defined; posterior ear of right 

valve short and narrow, posterior border slanting 

steeply. Posterior ear of left valve short with steeply 

sloping border; anterior ear unknown. Umbonal angle 

of moderate width, dorsal margins straight. Dorsal 

slopes of left valve and posterior dorsal slope of right 

valve moderately broad, undercut, and weakly concave; 

anterior dorsal slope of right valve narrow, forming a 

wide angle with the ear. Sculpture of right valve consisting of poorly to well-defined plicae which develop 

in the juvenile stage and tend to be obliterated in the 

gerontic stage. Left valve with medium to moderately 

broad, usually smooth plicae corresponidng to the interplicae of the right valve, likewise weak or absent in 

young juvenile and gerontic stages. Secondary sculpture of right valve consisting of moderately strong 

raised riblets, three to five on the plicae and four to 

five in the interplicae; riblets inequisized on some plicae 

with the larger riblets branching; at the beginning of 

the gerontic stage the riblets may split abruptly into

two to four smaller riblets. Interplicae of left valve 

with three to six narrow but sharply raised riblets; 

smooth plicae splitting at beginning of gerontic stage 

into three to five small riblets. Microsculpture of both 

valves reticulate or metal lathelike, strongest in the 

secondary interspaces but covering riblets and plicae 

as well.

Discussion. The closest known relative of this species is the form figured by Wood (1851, p. 27, pi. 5, 

figs. 2d-f) as Pecten tigrinus Muller var. y. According to Wood, P. tigrinus occurs in both the Coralline 

Crag (late Pliocene) and the Red Crag (early Pleistocene) ; the horizon of his figured specimen is not given. 

Most recent lists of Crag fossils only record P. tigrinus 

from the Coralline Crag. The number of plicae is the 

most 'obvious difference between C. trinitiensis and the 

form figured by Wood; C. trinitiensis has five plicae 

on its right valve and four strong plicae (with two 

weaker terminal plicae) on its left valve; Wood's figure 

shows four plicae on the right valve and three on the 

left valve. This arrangement of plicae results in a median plication on the right valve of C. trinitiensis and 

a median furrow on the right valve of C. tigrinus 

var. y.

Of the known Japanese species, C. trinitiensis most 

closely resembles C. cosibensis (Yokoyama). It is less 

like the Pliocene representatives of C. cosibensis (see 

Masuda, 1959b, pi. 13, figs. 1-9, 16-18) than the early 

Miocene form, 0. cosibensis hanzaivae (ibid., figs. 10- 

15). None of the Japanese forms exhibit the irregularity in the width of the secondary ribs seen in 0. 

trinitiensis, nor do the secondary ribs show the abrupt 

splitting of the secondary ribs into several smaller 

riblets.

As matters now stand, a Pacific origin for P. tigrinus 

var. y seems most likely. It is of interest to note that 

the gastropod Molleria costulata (Moller) occurs with 

0. trinitiensis. This minute but very characteristic gastropod has not been found elsewhere in the Pacific. 

MacGinitie (1959, p. 81) reported it living at Point 

Barrow, saying it had not been known previously outside the Atlantic. The occurrence of the species in Pliocene beds in the Gulf of Alaska strongly suggests communication with the Atlantic in Pliocene time.

Types: The holotype (USNM 644933) consists of a nearly 

complete right valve and an incomplete left valve, both belonging to the same individual. The right valve measures 41.5 mm 

in height and 38.5 mm in length. Two figured specimens are 

numbered USNM 644934, 644935.

Type locality: Near the center of the northwest side of Tugidak 

Island, Alaska, 320 ft below the top of a section computed to be 

3,520 ft thick, 56°31" N., 154°42" W., USGS M1494.
SYSTEMATIC PALEONTOLOGY 21

Chlamys ("Chlamys") aff. C. ("C.") trinitiensis MacNeil

Plate 8, figures 2-5, 7-9

Discussion, The middle part, of the section on Tugidak Island contains an assemblage of pectinids, known 

thus far only from fragments, that appears to be very 

closely related to C. trinitiensis. If the fragments figured here actually represent one species, as is believed, 

the species is extremely variable. Some of the more uniformly ribbed individuals (figs. 2, 4) approach C. cosibensis. Other individuals with fine secondary ribs or 

with coarse secondary ribs that divide abruptly into several finer ribs (figs. 3, 8) appear to be more closely related to C. trinitiensis. Still other individuals show a 

high degree of coalescence of the secondary ribs (fig. 9), 

and these individuals with their large smooth plications 

have some resemblance to the more plicated variants of 

C. chaixensis (pi. 9, figs. 7-10), here described, as well 

as to the more plicated variants of C. lioica (pi. 10, fig. 

1).

This series of forms may therefore have been derived 

from the C. cosibensis stock of Japan, but I am inclined 

to believe its immediate relationship is with C. pilicaensis Kukota. Several subsequent Alaskan species 

may be derived from it.

Figured specimens: The figured specimens are numbered 

USNM 644936-644942. They include fragments of both right 

and left valves.

Locality: Southwest side of Tugidak Island, south of Kodi'ak 

Island, Alaska, 1,900 ft above base of section estimated to be 

about 3,520 ft thick (horizon probably Pliocene), USGS M1895,

Group of C. (C.) rubida (Hinds) 

Chlamys (Chlamys) rubida (Hinds)

Plate 20, figures 7, 9; plate 22, figures 7, 8 

Pecten rubidus Hinds, 1845, Zoology of the Voyage of H.M.'S.

Sulphur, Mollusca, pt. 3, p. 61, pi. 17, fig. 5. 

Pecten hericeus var. navarchus Dall, 1898, Wagner Free Inst.

Sci. Trans., v. 3, no. 4, p. 708. 

Pecten (Chlamys) hastatus var. navarchus, Arnold, 1906, U.S.

Geol. Survey Prof. Paper 47, p. 112, pi. 43, figs. 1, la, b. 

Pecten (Chlamys) hastatus var. hindsii, Arnold, 1906, U.S. Geol.

Survey Prof. Paper 47, p. Ill, pi. 43, figs. 2, 2a. 

Pecten hindsii, Oldroyd, 1924 [1925], Stanford Univ. Pubs., Geol.

Ser., v. 1, no. 1, p. 53, pi. 7, figs. 3, 4. 

Pecten hindsii navarchus, Oldroyd, 1924 [1925], Stanford Univ.

Pubs., Geol. Ser., v. 1, no. 1, p. 54, pi. 4, figs. 2, 3. 

Pecten (Pecten) islandicus var. hindsii, Grant and Gale, 1931,

San Diego Soc. Natl. History Mem., v. 1, p. 163. (In

part.) 

Chlamys ru~bida, Grau, 1959, Allan Hancock Pacific Exped.,

v. 23, p. 76, pi. 24 (with extended synonymy).

Discussion. As one of the earliest described species 

from the Pacific, G. rubida has figured prominently in 

the general confusion regarding the so-called Pacific 

C. islandica. Right valves of both C. rubida, and O. r. 

hindsii have split ribs, suggesting an intergradation

22&-84S O 67 3

with C. islandica, to which C. r. hindsii has been referred by many authors. The left valve of typical 

C. rubida, however, has scabrous three-parted ribs and 

from one to three scabrous interstitial riblets, making 

it easily distinguishable from C. r. hindsii, which has 

coarser, more solid ribs. The specimens figured by 

Arnold as hindsii and navarchus very nearly represent 

the varietal extremes of typical C. rubida.

Superficially, the closest living species to G. rubida 

is C. hastata hericius (Gould); C. hericius probably 

forms a morphological continuum with the southern 

form, G. hastata (Sowerby), and most modern authors 

regard it as a subspecies of C. hastata. The morphological gap between C. h. hericius and C. rubida makes 

it unlikely, however, that there could have been any 

connection between these species since late Miocene or 

earliest Pliocene time.

I can find no authentic record of this species in East 

Asia. It has been reported from Hokkaido by Kuroda 

and Habe (1952, p. 16), Kira (1955, pi. 49, fig. 9), and 

Grau (1959, p. 79). The left valve figured by Kira 

has less-regular curved ribs ( Iberingiana) ; the ribs of 

C. rubida are straight. Furthermore, the left valve of 

C. rubida is rose or purplish; Kira's specimen is white. 

Neither C. rubida, C. herwius, or C. hastata is known 

in the Arctic or Atlantic regions.

Until recently the only problems concerning O. rubida 

were nomenclatural. Now that Martyn's "Universal 

Conchologist" (1784) has been declared invalid, Pecten 

rubidus Hinds is not a homonym of P. rubidus Martyn 

(= G. isl-andica]. Most recent authors have presumed 

the species to be identical with P. hindsii Carpenter and 

P. hericeus navarchus Dall. Palmer (1958, p. 70) presented evidence of a further mixup involving G. rubida. 

G. hindsii, and G. Mncaidi. According to Palmer, the 

name Pecten hindsii was given by Carpenter to a shell 

collected from Vancouver by H.M.S. Plumper; at that 

time Carpenter did not think it was the same species 

as P. rubidus Hinds. Unfortunately, the Plumper 

specimen (the type of P. hindsii} and the type of 

P. rubidus, which came from Alaska and was once in 

the British Museum, are now lost. It is not possible, 

therefore, to resort to the types for a solution.

Palmer further stated that the Carpenter collection 

in the Redpath Museum, Montreal, contains three specimens labeled by Carpenter as "Pecten hindsii Cpr. 

= rufoidus, H. C. Sitka" and six specimens labeled 

"'Pecten (?var.) hindsii Crp. = rubidus var. H. Cum. 

not Hinds. Neeah Bay. Swan" (Neah Bay is a village 

on the south shore of the Strait of Juan de Fuca). Here 

again is evidence that Carpenter had a form he thought 

was rubidus and a form he thought was not rubidus.
22 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Through the courtesy of Dr. Vincent Conde of the 

Redpath Museum, Dr. Leo G. Hertlein and I have reexamined all these specimens. Our conclusion is that 

Hinds' figure is perfectly clear and that it is the form 

that Dall named Pecten hericeus navarchus and Grau 

accepted as C. rubida; this is the form that Carpenter 

had from Neah Bay. The Sitka specimens (Palmer, 

1958, pi. 3, figs. 4-6), however, are the form which 

Grau (1959, p. 79) identified as C. rubida jardani and 

which probably includes among its variants the C. kincaidi of Oldroyd. This is the form that is commonly 

identified as G. islandica in southeastern Alaska. Inasmuch as Carpenter said his P. hindsii was more allied 

to C. islandica, whereas P. rubidus was more like 

hericius (in its more finely sculptured left valve), it 

would seem that the Sitka specimens represent the form 

Carpenter named P. hindsii; this is the reverse of 

Palmer's interpretation.

Large suites of specimens, both living and postglacial, 

from near Juneau, Alaska, show that these two forms 

merge through a continuous series of variants. They 

are here treated, therefore, as C. rubida and the subspecies C. rubida hindsii (^kincaidi}. G. rubida jordani is regarded as a Pleistocene and more southern 

subspecies.

Types: The holotype, the specimen figured by Hinds, was in 

the British Museum (Carpenter, 1864, p. 606), but according to 

Grau (1959, p. 78) it is now missing; three other syntypes are 

present. The figured specimen (USNM 150220) measures 56 

mm in height and 54.4 mm in length. Other figured specimens, 

U'SNM 644943, 644944.

Type locality: Alaska.

Locality of figured, specimens: Recent, south side of the 

Alaska Peninsula, TJSNM 150220; postglacial deposits, Juneau 

area, Alaska, USGS M212.

Other occurrences : The species is reported living from Bering 

Sea to Monterey, Calif.

Chlamys (Chlamys) rubida jordani (Arnold) 

Plate 22, figure 3; plate 24, figure 5

Pecten (Chlamys) jordani Arnold, 1903, California Acad. Sci.

Mem., v. 3, p. Ill, pi. 12, figs. 6, 7. 

Arnold, 1906, U.S. Geol. Survey Prof. Paper 47, p. 114, pi.

44, figs. 1, la, b. 

Oldroyd, 1924, Puget Sound Biol. Sta. Pubs., v. 4, p. 19, pi.

2, figs. 1, 2. 

Oldroyd, 1924 [1925], Stanford Univ. Pubs., Geol. Ser., v.

1, no. 1, p. 55, pi. 28, figs. 5, 6.

Discussion. The holotype of G. r. jordani has been 

suspected of being an abnormality. Woodring (in 

Woodring and others, 1946, pi. 32, fig. 16) illustrated a 

specimen from the Timms Point Silt (early Plestocene) 

of southern California as Ghlamys islandicus jordani.

This specimen is like one figured here (pi. 20, fig. 6) as 

G, rubida hindsii. Woodring (in Woodring and others, 

1946, p. 80) stated that G. i. jordani is living in Puget 

Sound but is not known to be living farther south. 

Grau (1959, p. 79) combined G. jordani and the living 

G. kincaidi as one subspecies, G. rubida jordani. Oldroyd (1924a, p. 17,19), on the other hand, thought both 

G. jordani and G. kincaidi were living in Puget Sound; 

she regarded kincaidi as a subspecies of G. hindsii 

(='nibida}.

Until a very thorough study of the early Pleistocene 

fossils from San Pedro and Santa Barbara and the Recent species of Puget Sound is made, there will be some 

doubt as to the identity of G. jordani and the validity of 

G. kincaidi. I am indebted to Dr. Leo G. Hertlein, of 

the California Academy of Sciences, for pointing out 

to me that there is a small species in the upper part of 

the San Diego Formation (horizon late Pliocene) at 

Pacific Beach, San Diego, a locality listed for the species by Arnold, that matches the description and figure 

of G. jordani. It is higher than long, has a reticulate 

microsculpture that covers the ribs and interspaces 

alike, and has minor shelflike resting stages. Oldroyd's 

comments indicate that she had a similar concept of G. 

jordani, but apparently she did not find anything like 

thjs living in Puget Sound. At the same time. Woodring's (in Woodring and others, 1946, p. 81) discussion 

of G. ancipleus sounds as though the small form with reticulate microsculpture all over the valves and shelflike 

resting stages is the young of that species.

I do not feel that a decision on C. jordani can be made 

without much more study, but I strongly suspect that 

G. jordani is a distinctive and identifiable subspecies and 

that it is typically southern. If this form should prove 

to be unidentifiable, all the specimens referred to it are 

referable to G. rubida hindsii.

I have not seen this subspecies from Alaska, or living 

anywhere, and as far as I am aware it is a southern Pliocene and early Pleistocene form.

Types: The holotype (USNM 162522) is a very large specimen for the subspecies, measuring 45 mm in height. 'Figured 

specimens USNM 644945, 644946.

Type locality: The holotype came from Deadman Island neai 

San Pedro, Los Angeles County, Calif.; a locality that no longer 

exists. Whether it came from an upper Pliocene or a lower 

Pleistocene horizon is not known.

Other occurrences: Fernando Formation (horizon uppermost 

Pliocene), Orange County, Calif., USGS M2130 (figured) ; Santa 

Barbara Formation (horizon uppermost Pliocene), Santa Barbara County, Calif., USGS M1918 (figured) ; San Diego Formation (late Pliocene) at San Diego, Calif.; Lomita Marl, Timms 

Point 'Silt, San Pedro Sand (all early Pleistocene) near Los 

Angeles, Calif.
SYSTEMATIC PALEONTOLOGY 23

Chlamys (Chlamys) rubida hindsii (Carpenter)

Plate 18, figures 4, 6; plate 19, figures 1, 3, 4, 6; plate 20, figures 

5, 6; plate 21, figure 4; plate 22, figures 1, 2; plate 24, figures

1,8,9

Pecten (?var.) hindsii Carpenter, 1864, British Assoc. Adv. Sci.

Kept. 33, p. 645. 

Pecten hindsii, Carpenter, 1872, Smithsonian Misc. Colln. No.

252, p. 606. 

Pecten kincaidi Oldroyd, 1920, Nautilus, v. 33, p. 135, pi. 4, figs.

3, 4.

Pecten (Chlamys) hindsii kincaidi, Ball, 1921, U.S. Natl. Museum Bull. 112, p. 18. 

Oldroyd, 1924, Puget Sound Biol. S'ta. Pubs., v. 4, p. 17, pi.

9, figs. 3, 4. 

Oldroyd, 1924[1925], Stanford Univ. Pubs., Geol. Ser., v. 1,

no. 1, p. 53, pi. 12, figs. 1, 2. 

Pecten (Pecten) islandicus var. Jordani, Grant and Gale, 1931,

San Diego Soc. Nat. History Mem., v. 1, p. 164, pi. 11, fig. 4. 

Chlamys islandicus jordani, Woodring, 1946, U.S. Geol. Survey

Prof. Paper 207, p. 80, pi. 32, fig. 16. 

Chlamys rubida jordani, Grau, 1959, Allan Hancock Pacific

Exped., v. 23, p. 79. pi. 25 (with extended synonymy).

Discussion. The holotype of C. kincaidi has smooth, 

broad, well-rounded ribs and narrow V-shaped interspaces. It does not compare in this respect with any 

other Recent specimen I have seen. There is little 

reason to doubt, however, that it is just an extreme 

variant of a species now living from Puget Sound to 

the Gulf of Alaska. The probability that Pecten 

hindsii Carpenter is an older name for this form was 

discussed under G, rubida.

Chlamys rubida hindsii is very closely related to and 

possibly descended from C. hancdshiensis. The most 

closely related form in early Pleistocene beds of Alaska 

is here described as C. luinai&hiemis anwhifkana, some 

variants of which are very similar to C. r. hindsii. In 

all probability the living American C. r. hindsii and C. 

pseudislandica are descended from different subspecies 

of C. hanaishiensis.

C. r. hindsii and C. pseudislandica are the two Pacific 

forms most commonly confused with C. islandica 

(Miiller).

Types: The holotype of C. rubida hindsii is lost. The holotype 

of Pecten kincaidi Oldroyd (SU 89), deposited at Stanford University, measures 40 mm in height and 38 mm in length. The 

largest figured specimen (USNM 644947), a right valve, measures 62 mm in both height and length. Other figured specimens 

are numbered USNM 644948-644952, 644956, 644957, 637741- 

637744.

Type locality: Recent, Vancouver (Carpenter, 1864).

Other occurrences: Puget Sound to the northern Gulf of 

Alaska. A large suite of specimens is in the U.S. Geological 

Survey collection from Excursion Inlet, southeastern Alaska, 

USGS M234. The species is abundant in postglacial deposits 

near Juneau, southeastern Alaska, where both normal and very 

coarsely ribbed variants occur: USGS 5256, 5461, M212, M214, 

M216-M218, M243.

Chlamys (Chlamys) cf. C. (C.) rubida hindsii (Carpenter) 

Plate 16, figure 3

Description. Shell small, weakly inflated, higher 

than long; disc nearly symmetrical. Anterior ear of 

left valve of moderate length and broad, margin weakly 

sinuous; posterior ear short, margin moderately inclined 

and weakly concave. Dorsal margins nearly straight. 

Dorsal slopes narrow, the anterior slope slightly 

broader and less undercut than the posterior slope. 

Sculpture consisting of thin smooth weakly raised ribs 

and weakly concave interspaces about twice as wide as 

the ribs. Initial stage of juveniles smooth and glassy, 

followed by a short interval in which faint ribs 'appear 

and the interspaces have a microsculpture consisting of 

faint concentric undulations. Late juvenile stage 

marked by a moderately 'abrupt appearance of reticulate 

or metal lathelike microsculpture that continues to the 

margin. Shell is nearly white with irregular brown or 

chestnut maculations which are arranged in two poorly 

defined rings. This form is known only from a left 

valve.

Discussion. I can find no previously described northern Pacific Chlamys with the extreme color pattern of 

this shell. The figured specimen is obviously juvenile. 

A large lot of C. r. hindsii from Excursion Inlet, southeastern Alaska, shows a tendency to have cream-colored 

maculations on a 'brownish-red background, but none of 

the shells are as nearly white as this specimen. The 

left valve of most specimens of C. r. hindsii of comparable size are brownish red; light-colored maculations or 

bands develop later. Furthermore, the beaks of young 

left valves of C. r. hindsii tend to be more inflated. This 

may be just a variety of C. r. hindsii* however, as that 

species is interpreted.

Figured specimen: USNM 637745, a left valve, measures 26 

mm in height and 22 mm in length.

Occurrence: Recent, beach on Douglas Island, just north of 

bridge, near Juneau. Alaska, USGS M213.

Chlamys (Chlamys) rubida prerubida MacNeil, n. subsp. 

Plate 11, figures 7, 8, 13

Description. Shell moderately small, left valve more 

inflated than right valve. Anterior ear of right valve 

moderately large and broad, byssal notch shallow and 

angulate, byssal area moderately broad; posterior ear 

short, posterior margin concave, becoming nearly vertical at the hinge line. Anterior ear of left valve unknown; posterior ear short, posterior margin slanting 

and weakly concave. Posterior dorsal margins slightly 

longer than anterior dorsal margins. Dorsal slopes of 

left valve slightly wider than dorsal slopes of right 

valve. Young juvenile stage of right valve smooth and
24 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

weakly undulating, faint radial ribs appearing as 

growth continues. Adult sculpture consisting of moderately small and closely set ribs. Bibs of right valve 

slightly larger centrally, some of the central ribs splitting abruptly in adults, terminal ribs finer and weakly 

beaded or scabrous, interspaces evenly rounded and 

about, the same width as the ribs, some interspaces having an interstitial riblet. Kibs of left valve finely scabrous, divided into primary, secondary, and tertiary ribs 

with finer interstitial riblets between them; primary and 

some smaller ribs double or three parted or irregularly 

divided. Microsculpture reticulate or metal lathelike 

and restricted to the interspaces of adult stage of the 

right valve and to very small patches on the left, valve; 

not present in juveniles.

Discussion. The microsculpture of the juvenile and 

adult stages of this subspecies is similar to that of both 

C. cf. C. hanaishiensis from the same locality (pi. 16, 

fig. 8) and Recent specimens of C. rubida. A large 

suite of specimens might show that C. r. prerubida, C. cf. 

C. hanaishiensis, and C. cf. G. cosibensis from this locality are all part of one intergrading series. Regardless of this possibility, they are regarded as the roots 

from which several subsequent species and subspecies 

were derived.

C. r. prerubida has finely scabrous ribs, as does G. 

rubida, and there is a similar tendency for the ribs of 

the left valve to be three parted. In both G. r. prerubida and G. rubida, the posterior dorsal margin is 

slightly longer than the anterior dorsal margin, the 

opposite of the condition in G. beringiana. In all probability G. r. prerubida is a direct ancestor of G. rubida.

While the exact relationship of the existing Pacific 

species G. rubida (Hinds), C. hastata (Sowerby), and 

G. h. hericius (Grould) is not fully understood and probably will not be until their Pliocene and Pleistocene 

history is better known, it seems likely that all of them 

originated in the Pacific. Arnold (1903, pi. 11, fig. 2) 

figured a specimen from the early Pleistocene of Deadman Island near San Pedro, Calif., as P. (Chlamys} 

hericeus. This specimen strongly resembles the fragment of G. r. prerubida shown here (pi. 11, fig. 8). G. 

hericius, which is regarded as a subspecies of C. hastata 

by most authors, may be the more archaic form of the 

species. G. hastata and C. rubida may prove, however, 

to belong to very distantly related sections of Chlamys.

Types: The holotype (USNM 644960), a right valve, has a 

height of 48 mm and a length of 42.5 mm. Two paratypes, 

both fragments of left valves, are numbered USNM 644961, 

644962.

Type locality: Near center of the northwest side of Tugidak 

Island, Alaska, 320 ft. below the top of a section computed to 

be 3,520 ft thick, 56°31" N., 154°42" W., USGS M1494.

Group of C. (C.) beringiana (Middendorff)

Chlamys (Chlamys) beringiana (Middendorff)

Plate 20, figure 2 ; plate 21, figures 2, 5-7 ;

plate 23, figures 3, 6; plate 24, figures 2, 3

Pecten islandlcus var. belirinffiana Middendorff, 1849, Beitrage 

Malacozoologia Bossica, St. Petersbourg Imp. Acad. Sci. 

Mem., ser. 6, v. 6, p. 528, pi. 13, figs. 1-3.

Clilamys ~beringianus, Pavlovsky, 1959, Atlas Invertebrates Far 

Eastern Seas USSR, Acad. Sci. Zool. Inst, Moscow-Leningrad, pi. 50, fig. 10.

Chlamys islandica, IteTiringiana, Grau, 1959, Allan Hancock 

Pacific Bxped., v. 23, p. 73. (In part.)

Discussion. The original drawings of this species are 

inadequate for positive identification; the ears as reconstructed in Middendorff's figures 1 and 2 are presumed 

to represent supposedly subjacent right valves. On the 

basis of the original figures, it would be difficult to distinguish this species from G. pugeten-sis (Oldroyd) (pi. 

22, figs. 4, 5).

Dr. A. O. Scarlato, Zoological Institute, Academy of 

Science, Leningrad, has kindly supplied me with photographs of two specimens stated to be the types of Pecten 

islandicus var. behringiana Middendorff. One photograph (pi. 24, fig. 2) is of the largest of the three specimens figured by Middendorff (1849, pi. 13, fig. 1), and 

it is here designated the lectotype. The other photograph (pi. 24, fig. 1) is of the specimen figured by Middendorff (1849, pi. 12, fig. 9) as Pecten rubidus Hinds? 

Middendorff discussed both forms under Pecten rubidus 

in his text. The lectotype of G. beringiana comes presumably from Bering Sea, possibly from off Kamchatka. 

The larger specimen that Middendorff identified in his 

plate explanation as P. rubidus comes presumably from 

Sitka.

I am not entirely certain of the identification of either 

of these photographs. I am inclined to believe, however, that the larger specimen, a left valve, from Sitka 

(pi. 24, fig. 1) belongs to the species here identified as G. 

rubida hindsii and that it is close to the variant from 

postglacial deposits near Juneau here figured on plate 

18, figure 4. Its ribs are slightly wider than on that 

specimen but otherwise the two specimens are very 

similar. A reticulate microsculpture covers both the 

ribs and interspaces on both specimens.

The identity of the lectotype of G. beringiana is much 

less certain. It has reticulate microscultpure on the 

early stages, but the interspaces of the later stages appear to be smooth. The primary ribs are of approximately the same size. Some of the interspaces have two 

interstitial riblets. The lectotype probably comes closest 

to the left valve of G. beringiana figured on plate 21, 

figure 5, but the latter has less-equisized ribs. Another 

left valve figured by Middendorff (1849, pi. 13, fig. 2)
SYSTEMATIC PALEONTOLOGY 25

has slightly curved inequisized ribs, and it may be the 

same species that Kira (1955, pi. 49, fig. 9) figured as 

Chlamys islandica hindsii. It wT ould appear that the 

lectotype of C. beringiana is one of the less discordantly 

ribbed variants of the species. Possibly this variant is 

more common along the eastern Asiatic coast, where it 

ranges at least as far south as Hokkaido. The lectotype 

is fairly close to a left valve figured by Pavlovsky (1955, 

pi. 50, fig. 10) as Chlmnys beringianus. A right valve 

with moderately uniform ribs (pi. 24, fig. 3) was 

collected from St. Lawrence Island.

The lectotype of C. beringiana (pi. 24, fig. 2) thus 

seems to represent the less extremely sculptured variants 

of the species. The opposite extreme of the species is 

represented by C. b. graui (Grau, 1959, pi. 23, fig. 2), 

which has crude high ribs that may or may not divide 

terminally and relatively narrow, deep interspaces that 

usually contain a single interstitial riblet.

Somewhat intermediate between these forms are the 

subspecies C. b. strategics and C. b. imalaskae. C. b. 

strategy* (Oldroyd, 1924b, pi. 41, figs. 1, 2), which has 

broad, rounded, nearly smooth ribs that may divide 

terminally and broad shallow interspaces, is the variant 

that most modern authors have regarded as typical C. 

beringiana. 0. l>. unalasJcae (pi. 20, figs. 1, 3-4) has 

broad, low, flattened fascicles with moderate broad, 

Shallow interfascicular depressions on the right valve 

and moderately strong fascicles with broader interspaces on the left valve. The riblets are almost evenly 

distributed but slightly stronger on the fascicles, and 

they have little or no tendency to divide with growth.

The most likely Pliocene progenitor of C. beringiana 

in the northern Pacific region is C. cosibensis (Yokoyama). A species from the upper part of the section 011 

Tugidak Island, here identified as Chlamys (Chlavnys} 

cf. C. (C.} cosibensis (pi. 11, figs. 9,11,12), is somewhat 

intermediate between C. b. strategics and the new subspecies, C. b. unalaskae. The peculiar flattening of the 

fascicles of the right valve that characterizes C. b. unalaskae is also found on some individuals of the Tugidak 

form (pi. 11, fig. 9). Typical C. cosibensis generally 

has more rounded fascicles, and on some individuals the 

fascicles are poorly developed.

Both rounded and flattened fascicles are found in 

/Swiftopecten. If Swiftopecten shares a common ancestry with the C. cosibensis group, as is here maintained, 

variants with flattened fascicles might be expected in 

either group. Very little is known, however, of the late 

Oligocene and early Miocene history of either /Swiftopecten or the C. cosibensis group. It is entirely possible 

that Pecten (Chlamys} hastatus var. ingeniosa Yokoyama (1929, p. 5, pi. 6, fig. 2), from the Nanao Formation (early Miocene) of the Noto Peninsula, west-central

Honshu, is closer to being in the actual line of descent of 

C. beringiana than is the early Miocene 0. cosibensis 

hanzawae (Masuda, 1959b, pi. 13, figs. 10-15).

Despite the apparent similarity of the more coarsely 

ribbed subspecies of C. beringiana to C. tjornesensis (pi. 

25, figs. 1-3) from the late Pliocene and early Pleistocene 

beds of Iceland, I am inclined to believe these forms are 

not intimately related. Both C. tjornesensis and C. 

breidavikensis (pi. 25, figs. 4-8), although resembling 

C. beringiana and C. islandwa, respectively, appear to 

be much more closely related to the European stocks of 

C. gloriamaris and C. tauroperstriata, and to be rather 

sharply delimited from C. beringiana and C. islandica. 

It may be found eventually that these forms do indeed 

have a common ancestry in early or middle Tertiary 

European species. I suspect at present, however, that 

representatives of these stocks migrated to East Asia by 

way of the Tethys and that species that developed subsequently in the northern Pacific reached the northern 

Atlantic secondarily by way of the Arctic. A much 

more complete knowledge of the intermediate f onns will 

be necessary before such a migration pattern can be 

demonstrated.

The amount of the shell thit is covered with reticulate or metal lathelike microsculpture varies geographically in C. beringiana if the specimens I have examined 

are consistently representative. Specimens of C. beringiana from Point Barrow to Point Hope and around 

Saint Lawrence Island have reticulate microsculpture 

over more of the shell, usually in all the interspaces, and 

sometimes on the ribs as well. Around Saint Paul 

Island, the microsculpture has not been observed on the 

ribs although it may cover all the interspaces. On some 

specimens, however, it is restricted to the early adult 

and even the juvenile stage. In the subspecies C. b. 

unalaskae from around Unalaska the microsculpture is 

usually found only on the juvenile stage of the shell and 

it may be absent entirely; in adults there are either fine 

radial lines or faint concentric undulations. The surface is excellently preserved on all specimens of C. b. 

unalaskae in the type lot.

Types: The type material is in the Akademiia Nauk USSR, 

Leningrad. The largest figured specimen (USNM 637749), an 

incomplete left Valve, measures 63 mm in height and 55 mm in 

length. Other figured specimens are numbered USNM 637746- 

637748, 637750; OAS 12613-12614, 12746.

Type locality: Recent, Bering Sea.

Locality of figured specimens: Saint Paul Island, Pribiloff 

Islands, GAS 18493, USGS M1621; Saint Lawrence Island, USGS 

D373; Wainwright, GAS 34337; Point Barrow, GAS 34333 ; Point 

Hope, USGS 1339.

Grau (1959, p. 75) says the species ranges from Bering Sea 

to British Columbia, but all specimens of the typical form I have 

seen are from the area between the Pribiloff Islands and Point 

Barrow, Alaska. Possibly Grau's Gulf of Alaska and more southern records are based on C. pugetensis.
26 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Chlamys (Chlamys) beringiana colvillensis MacNeil, n. subsp. 

Plate 18, figures 5, 7

Pecten (Chlamys} n. sp., Ball, 1920, U.S. Geol. Survey Prof.

Paper 125-C, p. 31. 

Pecten sp., MacNeil, 1943, Jour. Paleontology, v. 17, no. 1, p.

86, pi. 12, fig. 4. 

Chlamys hindsii, MacNeil, 1957, U.S. Geol. Survey Prof. Paper

294-C, p. 114, pi. 14, fig. 1.

Description. Shell subroimded and medium inflated. 

Anterior ear of the right valve, the only one known, 

moderately narrow; byssal area correspondingly wide. 

Byssal sinus moderately broad and well rounded at its 

inner extremity, not angulate. Dorsal margins nearly 

straight and anterior margin slightly longer; dorsal 

slope very narrow. Bibs strongest medially where they 

are broad, straight sided, and crudely three crested; 

medial interspaces broad and round bottomed, about as 

broad as the ribs. Terminally the ribs are narrower 

and distinctly two parted; the most anterior and posterior ribs are smaller and single. Left valves, known 

only from scraps, have moderately high ribs that are 

slightly narrower than interspaces; ribs are usually 

three crested. Reticulate or metal lathelike microsculpture present between the smaller terminal ribs but not 

between medial ribs; medial interspaces have concentric 

lines only, and those of the left valve are slightly frilled 

or scaly.

Discussion. This form is here made a subspecies of 

C. beringiana, but it could just as well stand as a distinct 

species. No other fossil pectinid from Alaska has the 

combination of characters exhibited by this form. The 

weakly inflated right valve and the three-crested nature 

of the medial ribs might suggest a relationship with C. 

rubida, as I believed originally. On the other hand, the 

slightly longer anterior dorsal margin suggests a relationship with C. beringiana. Until enough specimens 

have been found to show the full range of variation, it 

would be useless to speculate further on the exact relationships of this subspecies.

Types: The holotype (USNM 591912), an incomplete right 

valve, has a height of 62 mm and a length of 58 mm. The 

figured fragment from Nome is numbered USNM 644968.

Type locality: Colville River at Ocean Point, about 8 miles 

below the mouth of the Kikiakrorak River, northern Alaska, 

Gubik Formation (horizon probably early Pleistocene), USGS 

D306.

Other occurrences: Submarine Beach (late Pliocene or early 

Pleistocene), Nome, Alaska, USGS M1256; Submarine Beach 

or Intermediate Beach (middle Pleistocene), Nome, Alaska 

USGS 7477.

Chlamys (Chlamys) beringiana graui MacNeil, n. subsp. 

Not figured

Chlamys islandica ~behrmgiana>, Grau, 1959, Allan Hancock 

Pacific Exped. v. 23, pi. 23, fig. 2.

Discussion. This is the most coarsely sculptured 

form of 0. beringiana. It is closest to C. b. strategus 

and future collecting may show that it is only an extreme variant of that form. The ribs of C. b. graui 

are sharper and steeper sided than in C. b. strategus, and 

they extend more nearly to the beak. The interspaces 

of the left valve have a single strong interstitial rib. 

In C. b. strategus the ribs are broad and rounded and 

they break up near the margin into f asciclelike bundles. 

The interspaces are moderately broad and shallow, and 

they may contain several interstitial riblets.

It is presumed that the specimen figured by Grau 

from Saint Paul Island in the Pribiloffs, in the collections of the U.S. National Museum, is not one of the 

specimens on which Dall based his Pecten hericeus var. 

strategus; the latter form is stated to be from Unalaska.

The collection at Stanford University contains a left 

valve from Saint Paul that is almost identical with the 

left valve figured by Grau; it is bright red.

The most closely related known fossil form is C. coatsi 

middletonensis. C. b. strategus more nearly resembles 

C. c. middletonensis , however, than does C. b. graui.

Holotype: USNM 271731, measures 58 mm in height and 53 

mm in length.

Type Ideality: Recent, Saint Paul Island, Pribiloff Islands, 

Alaska.

Chlamys (Chlamys) beringiana strategus (Dall) 

Not figured

Pecten hericeus var. strategus Dall, 1898, Wagner Free Inst.

Sci. Trans., v. 3, pt. 4, p. 709. 

Pecten (Chlamys) islandicus beringianus, Oldroyd, 1924 [1925],

Stanford Univ. Pubs., Geol. Ser., v. 1, no. 1, p. 55, pi. 41,

figs. 1, 2.

Discussion. This subspecies has the long anterior 

dorsal margin typical of C. beringicma. The ribs are 

smooth and rounded in young adults, but they break up 

into fascicular bundles of riblets at a more advanced 

growth stage.

Among the fossil forms, it is probably most like some 

of the variants of the Pleistocene C. coatsi (pi. 15, fig. 

6), and, in turn, the Pliocene C. chaisoensis. The exact 

varietal succession between all these forms is not known 

at present, but in all probability they stem from some 

part of the C. hanaishiensis-C. cosibensis complex.

The early Pleistocene form from Santa Barbara, 

Calif., that Arnold (1906, pi. 44, figs. 2, 2a, 3,4) figured 

as Pecten (Chlamys} h-astatus var. strategus is not this
SYSTEMATIC PALEONTOLOGY 27

subspecies. It does not have an elongate anterior dorsal margin, and the left valve has a pronounced flattening in the young stages. The juvenile ribs of the right 

valve are bifid. Specimens, especially juveniles, of this 

form that I have examined do not impress me as being 

very closely related to C. l>. strategus. A specimen from 

beds of Pliocene age in Sulphur Canyon, Ventura 

County, Calif., figured by Grant and Gale (1931, pi. 

11, fig. 2) as Pecten (Pecten) beringianus appears to be 

a precursor of the Santa Barbara species. If all 

Arnold's specimens are on© species, I am inclined to 

agree with Woodring (in Woodring, Bramlette, and 

Kew, 1946, p. 81) that they are Chlamys ana/pl&us 

Woodring (ibid., pi. 34, fig. 15). No species from 

Alaska that I have examined has a juvenile stage like 

G. anapleus.

Type: Ball never illustrated his P. strategus and in his later 

papers he appears to have placed it in the synonymy of C. 

beringiana. No type was designated, but presumably the specimens on which he based it are in the U.S. National Museum.

Occurrence: Ball (1898) reported the occurrence as Pleistocene 

of Alaska and Recent at Unalaska; I do not know to what Pleistocene specimens he refers. Oldroyd's specimen is from Bering 

Sea. If and until the type is clarified, Oldroyd's figure is the 

best indication of the subspecies.

Chlamys (Chlamys) beringiana unalaskae MacNeil, n subsp. 

Plate 20, figures 1, 3, 4

Description. Shell of medium size and moderately 

inflated, right valve more inflated than left valve. 

Anterior ear of right valve moderately long and narrow, byssal notch moderately wide, moderately deep, 

and angulate. Anterior ear of left valve of moderate 

length and very broad, anterior margin weakly 

sinuous; posterior ear short, steeply sloping margin. 

Anterior dorsal margin longer and more concave than 

posterior margin. Dorsal slopes of moderate width 

and very slightly undercut. Ribs, particularly of the 

left valve, gently curving toward the anterior with 

growth. Right valve with broad, flat-topped fascicles 

and narrower, shallow, rounded interspaces; both 

fascicles and interspaces with moderately strong riblets that are more or less evenly spaced. Left valve 

with moderately strong fascicles and wider interspaces, both the facicles and interspaces with strong 

riblets, usually with two to four riblets forming the 

crest of the fascicles. The riblets extend without convergence to the juvenile stage; a few are added interstitially in the adult stage. The riblets of both 

valves have small closely set scales or beads. The 

microsculpture of the juvenile stage is usually 

reticulate or metal lathelike, but in adults the surface 

between the riblets is usually either smooth, marked 

by concentric growth lines, or bears very fine radial 

lines.

The left valve shown on plate 20, figure 3, has no 

reticulate sculpture in the juvenile stage. An unfigured fragment of a left valve has reticulate microsculpture on both ribs and interspaces, well into the 

adult stage.

Discussion. This is another of the peculiar forms 

that appears, on the basis of existing records, to be 

restricted to waters immediately surrounding Unalaska.

This form is made a subspecies of C. beringitma 

because of its longer anterior dorsal margin and 

because of the similarity of the right valve to right 

valves of typical G. beringiana, from the Pribiloffs 

(pi. 21, figs. 2, 7). Pending further knowledge of 

this subspecies, it might with equal justification be 

combined with G. isldndica, albida. G. islandica 

powersi has its reticulate microscultpture restricted to 

the juvenile stage, but a left valve of G. beringiana 

subsp.? from Point Hope (pi. 20, fig. 2) has reticulate 

microsculpture over the entire shell except for the 

narrow crest of a few ribs.

The left valve of G. ~b. unalaskae is bright orange 

and the right valve is yellowish with several concentric orange bands. Specimens of G. beringidna. 

from the Pribiloffs are mostly orange with narrow 

purple bands, and specimens from Saint Lawrence 

Island are mostly purple with orange bands. Specimens from Point Hope and Point Barrow are purple. 

There seems to be a color gradation in this species, 

therefore, from south to north. Grau (1959, p. 73) 

stated that C. islandica albida, the only living Alaskan 

form with which G. ~b. unalaskae might be confused, is 

white or very pale pink.

I can find no figures or descriptions of an Alaskan 

shell that could be this subspecies, and the type lot of 

10 whole and incomplete specimens may be the only ones 

ever found. It is undoubtedly a very rare pectinid.

Types: The holotype (USNM 637751), a right valve, measures 

55 mm in height and 42 mm in length. Two paratypes (USNM 

637752, 637753) are both left valves.

Type locality: Recent, Usof Bay, southeastern Unalaska 

Island, Aleutian Islands, Alaska, USGS D53. Picked up on the 

tidal flat.

Chlamys (Chlamys) wainwrightensis MacNeil, n. sp. 

Plate 18, figure 3; plate 19, figure 8, 9; plate 23, figures 4, 5 

Description. This species has a very inflated left 

valve and a very weakly inflated right valve. Shell relatively high for its width. Dorsal margins of unequal length with the anterior margin longer than the 

posterior margin, making shell slightly asymetrical. 

Dorsal slopes of right valve narrow, but those of the 

left valve broad, concave, and weakly undercut. Ribs 

of right valve low and rounded, straight sided; oc-
28 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

casional ribs are split, evenly or unevenly. The interspaces are gently rounded, and some interspaces have a 

small interstitial riblet. The left valve has higher and 

sharper ribs than the right valve; on some individuals 

nearly all ribs are split; other individuals have only one 

or two split ribs. Some individuals have a very weak 

tendency for the ribs to be differentiated into primary, 

secondary, and tertiary series. The interspaces are well 

rounded and usually roughened by growth lines. The 

microsculpture is reticulate or metal lathlike and covers 

most of the interspaces; it may or may not be present on 

the ribs. Right valves of living specimens have alternating broad orange and white bands, sometimes with a 

purple narrower band above the orange band; left 

valves are almost uniformly dark reddish purple.

Discussion. This species is recognized with certainty 

only along the coast of Chukchi Sea between Point 

Hope and Wainwright, Alaska. Its closest known relative is a form from the Okhotsk Sea that Kotaka 

(1962, pi. 34, figs. 18-23) referred to C. islandica 

erythrocomata.

G. waiwwrightdnsis resembles O. bermgiana by having 

an elongate anterior dorsal margin, but it differs from 

G. ~beringiana and its subspecies by being less inflated; 

the right valve is very weakly inflated. A large suite 

of specimens of C. rubida hindsii from Excursion Inlet, 

southeastern Alaska, shows a gradation form individuals with more typical inflated equilateral right 

valves to individuals with abnormally flat right valves 

and longer anterior dorsal margins. None of the left 

valves in this suite, however, have the ribs divided into 

primary, secondary, and tertiary series as in C. loainwrightensis.

There is some resemblance between 0. wainwriglitensis and C. tjornesensis (pi. 25, figs. 1-3) from supposed late Pliocene beds of Iceland. The left valves also 

recall left valves of the Pliocene forms here referred to 

G. cf. C. Jianaishiensis (pi. 9, fig. 4) and G. cJuiixensis 

(pi. 9, fig. 2). The exact relationship between all these 

forms is at present unknown, nor is it clear whether they 

originated in the Pacific Ocean or in the Atlantic Ocean. 

As was stated previously, stocks of European early 

Tertiary origin might have reached the northern Pacific 

by either an Arctic or a Tethyan route.

Types: The holotype (USNM 637756), a left valve, measures 

69 mm in height anl 61 mm in length. The para type (USNM 

637757) is a right valve from the same locality. Other figured 

specimens are numbered USNM 637754-637755', 637758.

Type locality: Recent, Point Hope, Alaska, USGS M1339.

Other occurrences: Recent, Wainwright, Alaska, USGS 

M2056, M2062, D318.

Group of C. (C.) picoensis (Waterfall)

Chlamys (Chlamys) picoensis (Waterfall)

Not figured

Pecten (Chlamys) islandicus picoensis Waterfall, 1929, California Univ. Pubs, in Geol. Sci., v. 18, no. 3, p. 83, pi. 5, 

figs. 2, 4.

Peoten (Chlamys) venturaensis Waterfall, 1929, California 

Univ. Pub. in Geol. Sci., v. 18, no. 3, p. 84, pi. 6, fig. 4.

Pecten (Pecten) islandicus var. hindsii, Grant and Gale, 1931, 

San Diego Soc. Natl. History Mem., v. 1, p. 163. (In part.)

Chlamys rubida, Grau, 1959, Allan Hancock Pacific Exped., 

v. 23, p. 77.

Discussion. While this species is closely related to 

Eecent G. islandica and the early Pleistocene subspecies 

such as C. i. kanagae, it is more intimately related to the 

substock of G. chinkopensis (Pliocene) and G. kinosliitai (Eecent). The Japanese forms are here regarded as subspecies of G. picoensis. All these forms 

are less closely related to G. rubida and G. r. hindsii 

than to C. islandica.

Types: The holotype of C. picoensis (UC 31419), a right valve, 

is smaller than the para type (UC 31417), a left valve; Waterfall 

gives the dimensions as, height 77 mm, length 82 mm, convexity 

of left valve 18 mm.

Type locality: Top of Pico Formation, northwest corner sec. 3, 

T. 3 N., R. 21 W., Ventura County, Calif., UC loc. 7100. The 

uppermost part of the Pico Formation may be of early 

Pleistocene age.

Other occurrences: Deadman's Island, San Pedro, Calif.

Chlamys (Chlamys) cf. C. (C.) picoensis chinkopensis Masuda 

and Sawada

Plate 11, figures 1-3, 5, 6, 10

IClilamys chinkopensis Masuda and Sawada, 1961, Japanese 

Jour. Geology Geography, v. 32, no. 1, p. 21, pi. 4, figs. 6, 7.

Discussion. This form is distinguished by its suborbicular, moderately inflated shell. It occurs with 

and may perfectly intergrade with the forms here identified as C. cf. C. Jianaishiensis^ C. cf. G. aosibensis, and 

G. trinitiensis. In Japan G. chinkopensis occurs in the 

Setana Formation (early Pliocene) in association with 

C. hanaishiensis Masuda, G. pilicaensis Kubota (see 

Masuda, 1962b, pi. 20, figs. 1, 2), and G. cosibensis 

(Yokoyama), forms that appear to be closely interrelated as are the members of the complex on Tugidak 

Island. Future collecting may show that all the above 

forms are one or, at the most, two species. Even so, 

the diversity of the complex and the possibility that it 

foreshadowed several subsequent species makes it desirable to recognize all the names applied to it, if only 

to designate varietal forms.

C. cosibensis is the oldest of the Japanese names. 

Masuda (1959b) made both Pecten turpiculus Yokoyama and P. heteroglyptus Yokoyama subspecies of
SYSTEMATIC PALEONTOLOGY 29

C. cosibensis. The extreme variants of both of these 

subspecies are less like typical C. cosibensis morphologically than are all the above-mentioned Setana and 

Tugidak forms, with the possible exception of

C. trinitiensis.

No attempt is made here to combine any of the 

Japanese species, and it should not be done, in my 

opinion, until the complete range of variation of the 

Pliocene Chlamys in both Japan and Alaska is better 

known. In all probability enough names have been 

proposed already to cover any resolution of the synonymy on the species level. Two forms described from 

early Pleistocene deposits of California, Pecten 

(Ghlamys) islandicus picoensis Waterfall (1929, p. 83, 

pi. 5, figs. 2, 4) and Pecten (Ghlamys} venturaensis 

Waterfall (ibid., p. 84, pi. 6, fig. 4) are closely related 

to both C. chinkopensis and C. hanaishiensis, and it is 

thought to be desirable from the evolutionary standpoint, and for reasons of priority, to treat some of the 

younger Japanese species as subspecies or varieties of 

the previously named California species. The interests 

of the stratigraphic paleontologist are best served by 

stressing similarities in variation rather than minute 

and often individual morphological differences. A 

judicious use of species, subspecies, and varieties is the 

best means of showing evolutionary and migrational 

patterns, and it should be the goal of paleontologists to 

express these relationships in the nomenclature.

Figured specimens: The largest figured specimen (USNM 

644977), a right valve, measures 56 mm in height and 54.4 mm 

in length. Other figured specimens are numbered USNM 

644978-644982.

Locality of figured specimens: Near the center of the northwest side of Tugidak Island, Alaska, 320 ft below the top of a 

section computed to be 3,520 ft thick, 56°31" N., 154°42" W., 

USGS M1494; near the base of the section on Middleton Island, 

Alaska, approximately 2,000 ft below the top of the Chlamys 

(Leochlamys) tugidakensis zone, USGS M1753.

Chlamys (Chlamys) picoensis kinoshitai Kubota

Plate 24, figure 11

Chlamys erythrocomata, Kinoshita and Isahaya, 1934, Hokkaido Fish Bxp. Sta. Kept. Aquatic Products, v. 33, no. 

1, pi. 11, fig. 75.

Chlamys islandica var. Jcinoshitai Kubota, 1950, Shinsedai-noKenkyu (Cenozoic Research), no. 6, p. 16. [In Japanese.]

Chlamys islandica erythrocomata, Kira, 1955, Coloured illustrations of the shells of Japan, pi. 49, fig. 13.

Discussion. Masuda (1962b, p. 167) combined this 

form with his C. hanaishiensis which he described from 

the Setana Formation (early Pliocene) of Hokkaido. 

I hesitate to take a firm stand on matters involving the 

identity of Asiatic species without access to specimens, 

but I am not convinced that Masuda was correct nomenclaturally in rejecting the name kinoshitai. According

to Masuda, the name was only suggested and Kubota did 

not provide a figure or a description. The International 

Code of Zoological Nomenclature of 1961 states that 

prior to 1961 a variety name proposed conditionally is 

valid. Furthermore, Kubota's name is based on Kinoshita and Isahaya's figure, and he contrasted it with his 

C. islandica osugii. In my opinion, this meets all the 

requirements of the Code. Apparently Masuda felt that 

clarification could only be accomplished by rejecting 

kinoshitai.

C. p. kinoshitai is probably a direct linear descendent 

of C. p. chinkopensis. Inasmuch as G. p. chinkopensis 

occurs with C. hanaishiensis in the Pliocene beds of Tugidak Island, and the young of the two forms are not 

easily separable, a close relationship between them is 

indicated. It is my belief, however, that C. p. chinkopensis gave rise to the group of C. islandica, whereas 

G. hanaishiensis gave rise to the group of G. pseudislandica and probably had a common origin with the 

group of G. rubida. Of the known forms, the most 

likely connective between G. p. chinkopensis and G. 

islandica appears to be G. i. kanagae.

Judging from Eecent specimens I have examined, a 

more nearly complete morphological continuum exists 

between G. p. kinoshitai and G. pseudislandica than between the former and G. rubida or G. rubida hindsii. 

The present geographical distribution of these forms 

shows a similar relationship; G. p. kinoshita and G. 

pseudislandica are distributed from Point Barrow to 

northern Bering Sea and along the northern Asiatic 

coast, whereas C. rubida ranges from the Gulf of Alaska 

to Puget Sound. G. rubida is believed to be related to G. 

hanaishiensis through G. hanaishiensis aindutkana, 

whereas G. pseudislandica, typical G. hanaishiensis, and 

G. p. chinkopensis form a more direct lineage.

Types: The holotype (in the collections of the Hokkaido Fish 

Experiment Station) is from Araito Island in the northern 

Kurile Islands, west of the southern tip of Kamchatka. The 

specimen figured by Kira is from "north of Chishima" (north 

of theKuriles).

Group of C. (C.) hanaishiensis Masuda 

Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda

Plate 9, figures 1, 3-5; plate 10, figures 6, 9-11; plate 11, figure 

4; plate 16, figure 8

IChlamys hanaishiensis Masuda, 1962, Tohoku Univ. Sci. Repts., 

2d ser. (Geology), v. 33, no. 2, p. 166, pi. 22, figs. 1, 2.

Discussion. Masuda described G. hanaishiensis from 

the Setana Formation (early Pliocene) of Hokkaido. 

The specimens from Tugidak Island figured here are 

very similar to the Setana form. According to Masuda, 

the species still lives in the Okhotsk Sea, Bering Sea, 

and the northern Pacific. He thus made it include the
30 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Pacific forms that previous authors had referred to 

either O. islandica, O. kincaidi, or O. erythrocomata. 

A revision as important as this warrants more explanation than Masuda gives.

As here interpreted, typical O. hanaishiensis is restricted to the Pliocene. One Pleistocene subspecies is 

described. O. hanaishiensis is closely related to O. 

trinitiensis, and it may have had a common origin with 

that species; the exact nature of their relationship is 

not known at present. O. otukae Masuda and Sawada 

(1961, p. 19, pi. 4, figs. 1-5), an early and middle Miocene species from Japan, may be the direct ancestor of 

G. hanaishiensis.

All the forms here recorded from Tugidak Island, 

O. trinitiensis, O. cf. O. hanaishiensis, and O. cf. O. p. 

chinkopensis, have nearly identical juvenile stages. 

Following an initial smooth stage that persists for about 

2 mm of growth, there is a stage having very fine 

scarcely raised ribs with diagonal Gamptonectes-V&s 

microsculpture in the interspaces. This stage is followed after about 10-12 mm of growth by an enlargement of the ribs to more or less their adult shape and 

by a transformation of the microsculpture from diagonal to reticulate. The change from diagonal to reticulate microsculpture takes place earlier and more 

gradually toward the margins and later and more abruptly on the central part of the disc. The juvenile stage 

of Recent C. islandica is similar except that the diagonal 

microsculpture is more subdued and may be absent on 

the central area; in such specimens the interspaces are 

smooth. It is inferred from the similarity of the juveniles that all these forms are closely related.

The ribs of the left valve of O. hanaishiensis tend to 

be of unequal size (not as fascicles or bundles of riblets). While the ribs are of more equal size in O. 

hanaishiensis than in some other species, such as O. 

chaixensis and C. coatsi, a rather close relationship 

between these species is indicated. The Pleistocene subspecies, O. pseudislandica plafkerl and O. h. amchitkana, both have variants with little or no difference in 

the size of the ribs on the left valve.

O. hanaishiensis and the related C. rubida hindsii and 

C. picoensis kinoshitai belong to a group of northern 

Pacific pectinids that is frequently included in but is 

clearly distinct from the Atlantic species, C. Islandica 

(Mtiller). As here construed, typical O. islandica does 

not live in the Pacific Ocean area or along any part of 

Arctic Alaska. The O. islandica group probably originated in the Pacific, however, and two subspecies from 

Pleistocene beds are here described; the only surviving 

Pacific subspecies are C. islandica albida (Dall) (Arnold, 1906, p. 136, pi. 52, figs. 2, 2a) from Unalaska, and 

C. i. erythrocomata (Dall) (see pi. 21, figs. 8, 9) from

the Okhotsk Sea. The situation is complicated by the 

fact that at least one related Pacific form, O. pseudi-slandica, also migrated to northern Europe in late 

Pleistocene time (see Pecten islandicus, Wood, 1851, 

p. 40, pi. 5, fig. 1) ; this species occurs in the Clyde beds 

of Scotland. The acceptance of Wood's specimen as 

a variant of O. islandica has given the impression that 

O. islandica is much more variable than it actually is.

Figured specimens: The largest figured specimen (USNM 

644983) measures 67 mm in height and 57 mm in length. Other 

figured specimens are numbered USNM 6449'84-644990.

Locality of figured specimens: Near the center of the northwest side of Tugidak Island, Alaska, 320 ft below the top of a 

section computed to be 3,520 ft thick, 56°31" N., 154°42" W., 

USGS M1494; upper part of Yakataga Formation (horizon 

probably Pliocene), Lituya district, Alaska, USGS D184, D222, 

M1969.

Chlamys (Chlamys) hanaishiensis amchitkana MacNeil, n. subsp.

Plate 12, figures 3, 5; plate 13, figure 8; plate 14, figures 1, 2, 

4, 5; plate 15, figure 4; plate 22, figure 6

Pecten (Chlamys) islandieus, Stewart and MacNeil in Powers 

Coats, and Nelson, 1960, U.S. Geol. Survey Bull. 1028-P, 

p. 543.

Description. This subspecies ranges from forms in 

which the ribs of the right valve remain undivided 

throughout the life of the individual to forms in which 

the ribs divide at an early age. Left valves of the 

former type have ribs of nearly uniform size; left 

valves of the latter type have single, moderately strong 

interstitial riblets between the main ribs.

Discussion. The variants with divided ribs and interstitial riblets are very closely related to C. rubida 

jordani (pi. 22, fig. 3; Woodring and others, 1946, pi. 

32, fig. 16, as O. islandicus jordani). Typical O. r. 

jordani probably is a migrant of some part of this stock 

to southern waters. G. h. amchitkana grew to a much 

larger size than any known specimen of G. r. jordani.

This form resembles O. pseudislandica plafkeri except for a greater tendency for the ribs to split and a 

greater tendency for the ribs of the left valve to be of 

equal size. G. h. amchitkana. may prove to be no more 

than a variant of G. p. plafkeri, but the prevalence of 

this form on Amchitka and G. p. plafkeri on Middleton 

suggests there may be a geographical sorting as well.

Two different collections of pectinids have been made 

from Pleistocene deposits at the head of South Bight, 

Amchitka Island. While no stratigraphic distinction 

has been made, the fossils suggest that more than one 

stage of the Pleistocene is represented. The collection 

containing G. h. amchitkana yielded Foraminifera that 

Cushman and Todd (in Powers and others, 1960, p. 

543) compared with the fauna of the Timms Point Silt 

(early Pleistocene) of California. The pectinids in
SYSTEMATIC PALEONTOLOGY 31

this collection are leached and chalky. Another collection of fossils contains different pectinids, G. coatsi, G. 

coatsi middletonensis, and C. islandtea powersi. The 

shells in this collection are comparatively fresh, and 

some specimens are brightly colored. While the bay 

head fill has small areal extent, more than one period 

of fill is likely.

Types: The holotype (USNM 644991), an incomplete right 

valve, measures 93 mm in height and 88 mm in length. Other 

figured specimens are numbered USNM 014992-644999.

Type locality: Poorly bedded loose sand and gravel forming 

a fill about 75 ft thick at the head of South Bight, Amchitka 

Island, Aleutian Islands, Alaska, USGS 16908.

Other occurrences: Middleton Island, USGS 17743, 17744.

Chlamys (Chlamys) pseudislandica MacNeil, n. sp. 

Plate 19, figure 7; plate 20, figure 8; plate 23, figures 1, 2

Pecten islandicus, Wood, 1851, Palaeontographical Soc. London,

v. 4, pt. 2, no. 1, p. 40, pi. 5, fig. 1. 

Pecten (Chlamys) islandicus, Ball, 1898, Wagner Free Inst. Sci.

Trans., v. 3, pt. 4, p. 735. (In part.) 

Arnold, 1906, U.S. Geol. Survey Prof. Paper 47, p. 113. (In

part.) 

Pecten (Pecten) islandicus, Grant and Gale, 1931, San Biego

'Soc. Nat. History Mem., v. 1, p. 161. (In part.) 

Chlamys islandica, Morris, 1952, A Field Guide to Shells of the

Pacific Coast and Hawaii, p. 17, pi. 4, fig. 4. 

MacGinitie, 1959, U.S. Natl. Museum Proc., v. 109, no. 3412,

p. 155, pi. 19, fig. 4.

Grau, 1959, Allan Hancock Pacific Exped. v. 23, p. 69. (In 

part.)

Description. Valves moderately inflated, ranging 

from subrounded to higher than long. Anterior ear of 

right valve moderately short and broad; byssal notch 

narrow and angulate. Anterior ear of left valve moderately short with sinuous anterior margin. Both posterior ears short with moderately sloping concave margins. Anterior dorsal margins shorter than posterior 

margins. Anterior slopes moderately broad, those of 

left valve broader and more undercut than those of 

right valve. Sculpture moderately coarse, the ribs 

ranging from moderately broad to medium sized, 

roughened by crude growth lines. Ribs of right valve 

usually splitting evenly in adult stage and strongly divided at margin in full-grown specimens, interspaces 

usually with a single moderately strong interstitial riblet. Ribs of left valve narrower, split, and with a 

strong interstitial riblet; usually three ribs are slightly 

stronger and lighter colored than the rest. A reticulate or metal lathelike microsculpture is present in interspaces, both primary and secondary; tops of ribs 

have concentric sculpture.

Discussion. Ribs of this subspecies are coarser, 

higher, and have a greater tendency to split, especially 

on the left valve, than do the ribs of O. rubida liindsii. 

C. r. hindsii tends to be longer and less inflated, whereas

O. pseudislandica tends to be higher and more inflated. 

The left valve of G. pseudislandica is usually dark reddish purple.

The most apparent difference between G. islandica 

and G. pseudislandica lies in the ribs; the ribs of G. 

pseudislandica are coarser, plainer, and have a strong 

tendency to divide toward the margin; the ribs of O. 

islandica are finer, more frilled, and have less tendency 

to divide terminally, although some ribs may divide in 

an early growth stage.

Grau seems to have been the first author to exclude 

0. islandica from the Pacific and Bering Sea, but he 

recognized the species in Arctic Alaska. In my opinion, the typical form of the species is not known living 

or fossil in the Pacific, Bering Sea, Chukchi Sea, or the 

Beaufort Sea. It probably does not live east of Novaya 

Zemlya.

G. isl-andica probably had a Pacific origin, but the 

typical form developed in Atlantic waters. The facts 

that G. pseudislandica has until quite recently been 

identified as G. islandica. and the probability that G. 

pseudislandica also migrated to the northern Atlantic 

region in late Pleistocene time have contributed to the 

almost universal combination of these two forms.

The specimen figured by Wood (1851, pi. 5, fig. 1) 

from the Clyde beds (late Pleistocene) of Scotland 

could well have come from Point Barrow; it is typical 

of G. pseudislandica in every respect. According to 

MacGinitie (1959, p. 155), a specimen examined by her 

from Vads0, Norway, has broad primary ribs that divide. Norwegian specimens should be reexamined to 

see whether there actually is a form living there that 

can be distinguished from typical G. islandica. MacGinitie mentioned a specimen from Massachusetts Bay 

that resembles the Point Barrow form, and Grant and 

Gale (1931, pi. 11, figs. 1 a, b) figured one from Eastport, Maine. While MacGinitie gave measurements for 

19 specimens from Point Barrow, the specimen she 

figured appears to be a young adult. The holotype 

figured on plate 23, figures 1, 2, was dredged by Dr. 

G. D. Hanna, of the California Academy of Sciences.

G. pseudislandica is now living as far south as Saint 

Lawrence Island in northern Bering Sea, but it is not 

known to be living farther south. It has not been 

found fossil in Alaska. At the present time there is a 

geographical and morphological gap between this subspecies and G. rubida. Specimens from Point Barrow 

exhibit considerable range in the width of the ribs. 

The narrow ribbed subspecies, G. p. arconis (pi. 23, figs. 

7, 8) probably comes as close to G. picoensis kinoshitai 

as any Alaskan specimen I have seen. Its relationship 

to G. islandica is also apparent, but in my opinion the
32 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

stocks of C. islandica and C. picoensis became distinct 

in early Pleistocene time.

C. pesudislcmdica probably is the form Masuda 

(1962b, p. 167) had in mind when he said C. hanai-shiensis is living in Bering Sea; however, he made the type of 

C. li-anaisliiensis a specimen from the Set ana Formation 

(early Pliocene). Masuda also included O. picoensis 

kinoshitai (Kubota, 1950, p. 16; based on the O. erythrocomata of Kinoshita and Isahaya, 1934, pi. 11, fig. 75) 

in C. hanai-skiensi-s. To justify the name O. hanaishiensis, Masuda maintained that the name O. Mnoshitai was 

invalid. In my opinion, the name C. Mnoshitai is valid, 

but I do not believe the form so named should be combined with the early Pliocene C. lian-aishiensis.

Types : The holotype (GAS 12612) measures 73.5 mm in height 

and 69.5 mm in length. Figured specimens, USNM 637759, 

637760.

Type locality: Recent, off Point Barrow, Alaska, CAS loc. 

34358.

Other occurrences: Known to be living from Point Barrow, 

Alaska, to Saint Lawrence Island, northern Bering Sea USGS 

D373.

Chlamys (Chlamys) pseudislandica plafkeri MacNeil, n. subsp. 

Plate 12, figures 1, 2, 6, 7; plate 13, figures 1, 2

Pecten islandicus, MacNeil in Miller, 1953, Jour. Geology, v. 61, 

no. 1, p. 29.

Description. Shell moderately large, left valve more 

inflated than right valve, valves higher than long. Kibs 

of right valve moderately wide to moderately narrow, or 

of unequal width, rounded and somewhat crude, entire 

or divided into two and rarely three parts toward the 

margin, interspaces opposite primary ribs of left valve 

wider, deeper, and sometimes with an interstitial riblet. 

Ribs of left valve weakly divided into primary, secondary, and tertiary ribs, the tertiary ribs numbering one 

or two between different secondary and primary ribs, 

higher and sharper than on right valve.

Discussion. Specimens from Middleton Island referred to this subspecies are larger and more rounded 

than specimens of C. cf. C. lianaishiensis from supposed 

Pliocene beds on Tugidak Island.

The specimens of C. cf. C. hanisMensis from Pliocene beds in the Lituya district (pi. 10, figs. 6, 9-11) are 

also smaller than C. p. plafkeri and some of the specimens are lopsided. If this lopsidedness proves to be a 

characteristic that is not due to distortion, this variant 

is in need of a name. They occur both above and below 

other beds containing Olinocardium meekianum 

(Gabb), a species believed to be restricted to the 

Pliocene.

C. hanaishiensi-s amchitkana, occurs with C. p. plafkeri 

on Middleton Island, but so far only the former has been 

found on Amchitka Island in the Aleutians. C. li. amchitkana has narrower ribs, and they have more of a 

tendency to split toward the margin; the ribs of the left 

valve are all nearly the same size.

O. p. plafkeri appears abruptly in the Middleton Island section; its first occurrence is in a bed immediately 

above the highest bed, USGS 17746, containing O. (Leochlamys) tugidakensis. Miller's (1953, p. 23) stratigraphic section for Middleton Island shows that within 

some 3,675 feet of glacial marine sediments there are 

numerous beds of cobble-sized conglomerate. The conglomerate in which O. p. plafkeri first appears, USGS 

17745, is the only one of these conglomerates, or the only 

part of the section for that matter, that marks a change 

in the pectinid fauna. The top of the range of O. (L.) 

tugidakensis is taken tentatively as the top of the Pliocene. Typical C. p. plafkeri is taken to mark the beginning of the Pleistocene. O. coatsi middletonensis, 

which appears for the first time with C. p. plafkeri, is 

also known from supposed Pleistocene beds on Amchitka 

Island.

The more coarsely ribbed variants of C. p. plafkeri approach the less coarsely ribbed variants of C. coatsi middletonensi-s. Possibly not enough specimens are at hand 

to show beyond all question that these two forms do not 

merge, but I do not believe they do. O. pilicaensis 

Kubota (see Masuda, 1962b, pi. 20, figs. 1, 2), described 

from the Setana Formation (early Pliocene) of Hokkaido, is intermediate bewteen these two forms, however, 

and they are either descended from C. pilicaensis or all 

three forms descended from a common immediate ancestor. Masuda said that C. pilicaensis still lives in the 

northern Pacific; this is probably an allusion to C. beringiana or the subspecies O. b. graui.

It must be recognized that the abrupt appearance of 

C'. pseudislandica plafkeri and C. coatsi middletonensis 

in the Middleton Island section is due to a migration 

from elsewhere. While it is possible that these are Atlantic migrants, I believe they are more like preexisting 

Japanese species than any known forms in northern 

Atlantic or European beds.

Types: The holotype (USNM 645002) has a height of 88 mm 

and a length of 81 mm. A large incomplete unfigured specimen 

has a height of 100 mm. Other figured specimens are numbered 

USNM 645003-645006.

Type locality: Conglomeratic sandy mudstone 2,185-2,695 ft 

above base of a 3,675-ft section, near north end of Middleton Island, Alaska, USGS 17745 (for description of section, see Miller, 

1953, p. 23).

Other occurrences: Middleton Island, same bed as above and 

higher beds in section, USGS 17743, M1742, M1743, M2054.
SYSTEMATIC PALEONTOLOGY 33

Chlamys (Chlamys) pseudislandica arconis MacNeil, n. subsp. 

Plate 23, figures 7, 8

Discussion. This subspecies differs from typical C. 

pseudislandica by its finer ribs, of which only a few 

have any tendency to divide, and by its longer ear and 

broader byssal notch. Since only one specimen like this 

has been seen, it may be no more than an extreme variant 

of C. pseudislandica. This specimen, dredged from a 

depth of 300 feet, was alive when taken.

Holotype: The holotype (CAS 12747) measures 71 mm in 

height and 66.5 mm in length; the double convexity is 30 mm.

Type locality: Arctic Ocean about 17 miles west of Arcon 

Beach, 71°21'30" N.. 157°23'00" W., CAS 34347.

Group of C. (C.) islandica (Miiller) 

Chlamys (Chlamys) islandica islandica (Miiller)

Plate 18, figure 8; plate 19, figures 2, 5; plate 24, figures 12, 13

Peoten islandicus Miiller, 1776, Prodromus Zoologiae Danicae,

v. 32, p. 248.

Fabricius, 1780, Fauna Groenlandica, v. 16, p. 415. 

Pecten rubidus, Martyn, 1784, Universal Gonchologist, v. 4, p.

153, fig. 1, (non Hinds, 1845).

Chlamys islandica, Roeding, 1798, Museum Boltenianum, p. 161. 

Pecten (Chlamys) islandicus, Dall, 1898, Wagner Free Inst. Sci.

Trans., v. 3, no. 4, p. 735. 

Arnold, 1906, U.S. Geol. Survey Prof. Paper 47, p. 113, pi.

45, figs. 1, la. 

Pecten (Pecten) islandicus, Grant and Gale, 1931, San Diego

Soc. Nat. History Mem., v. 1, p. 161, pi. 11. (In part.) 

Chlamys islandica, Grau, 1959, Allan Hancock Pacific E'xped., v.

23, p. 69, pi. 22 (with extended synonymy).

Discussion. Other names proposed for this species 

include Ostrea cinndbarina Born, Ostrea demissa 

Solander, Pecten pealeii Conrad, Pecten fabricii 

Philippi, Chlamys islandica var. insculpta Verrill, and 

Chlamys costellata Verrill and Bush. It is perhaps remarkable that Linne did not have a clear concept of this 

species. According to Dodge (1952, p. 178-179), the 

box which bears the name Ostrea pusio in Linne's collection contains a right valve of C. islandica., as well as 

odd valves of several other species.

Other unsegregated valves of C. islandica were in 

Linne's collection. The types of Lepas balanus Linne 

(=Balanus balanus) (Pilsbry, 1916, pi. 33, fig. 1) are 

attached to a fine left valve of C. islandica. Pilsbry 

identified the substrate valve as Pecten opercularis 

Linne, but whether the misidentification is his or Linne's 

is not clear; at least Dodge did not mention an association of C. islandica and C. opercularis in Linne's collection. No 'better evidence of the general confusion 

concerning C. islandica needs to be cited.

The so-called Chlamys islandica in the northern Pacific have troubled systematists for years. While typical C. islandica belongs to the same section of Chlamys

228-848 O 67 4

as the northern Pacific forms, the stocks have been distinct since early Pleistocene time and possibly earlier. 

Several authors (Arnold, 1906, pi. 45, figs. 1, la; Oldroyd, 1924b [1925], pi. 8, figs. 1,2; Grant and Gale, 1931, 

pi. 11, figs. 1, la; Grau, 1959, pi. 22) have figured specimens from the Atlantic coast and Greenland with discussions of northern Pacific species referred to C. islandica. 

While the locality of these specimens has 'been clearly 

Stated, the illustration of Atlantic rather than Pacific 

specimens has given an entirely false impression of the 

Pacific species. Several species or subspecies have been 

described from the northern Pacific region, based, unfortunately, on unusual or juvenile specimens. Without access to large suites of the taxa involved, it might 

be difficult to determine beyond all question which taxa 

the named species represent. I am inclined to believe 

that the valid species have been named, however atypical the holotypes might be.

Several distinct species of Chlamys that either in 

whole or in part have been included in C. islandica are 

now living in the area between Puget Sound and Point 

Barrow. One type has valves of nearly equal inflation 

and dorsal margins of nearly equal length. The ribs 

range from broad and rounded to sharp and high and 

from moderately split to strongly split, sometimes multiple. This type includes C. rubida, the subspecies C. 

rubida hindsii, and a new species, C. pseudislandica. 

The other type has a longer anterior dorsal margin. It 

includes two subtypes. One has valves of nearly equal 

inflation and a wide range in the width of the ribs, particularly in the development of f ascicular bundles; this 

subtype probably includes typical C. beringian-a of Middendorff. The other, known from a single species, has 

a very weakly inflated right valve, a moderately inflated 

left valve, and a moderate division of the ribs on the left 

valve into wider primary ribs and weaker secondary 

and tertiary ribs; the primary ribs are not appreciably 

higher than the other ribs. This latter species is here 

named C. wainwrightem'is; a possible representative of 

this group is living in the Okhotsk Sea (Kotaka, 1962, 

pi. 34, figs. 18-23; identified as C. islandica 

erythrocomata).

Despite longstanding confusion over the point, typical 

C. islandica does not live in Alaskan waters or anywhere 

in the northern Pacific region. The species probably 

descended, however, from the stock of C. picoensis 

chinkopensis Masuda and Sawada (1961, pi. 4, figs. 6, 

7) and C. imanishii Masuda and Sawada (ibid., figs. 

lOa-c, 11), both from the early Pliocene of Japan. Very 

closely related forms are here recorded from supposedly 

late Pliocene beds of Tugidak Island, Alaska. A related but somewhat more advanced form was described 

by Waterfall (1929, p. 83, pi. 5, figs. 2, 4) from the
34 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

upper (early Pleistocene?) part of the Pico Formation 

as Pecten (Ghlamys] islandicus picoensis, and (ibid., 

p. 84, pi. 6, fig. 4) Pecten (GJilamys] venturaensis; these 

supposedly different species probably are identical. G. 

chinkopensis is here regarded as a subspecies of C. picoensis. At any rate, C. picoensis is close to the borderline 

morphologically between G. chinkopensis and the earliest known subspecies of C. islandica. It is not entirely 

clear at present, however, just how C. p. chinkopensis, 

C. cosibensis, and G. hanaishiensis are related.

The oldest subspecies of C. Islandica here recognized 

is C. i. kanagae, from beds of early Pleistocene age on 

Kanaga Island in the Aleutians. This subspecies ranges 

from strongly fasciculate to noiifasciculate. Both of 

the living Pacific subspecies, 0. i. albida and C. i. erythrocomata, are moderately fasciculate.

Chlamys islandica now lives in the northern Atlantic 

region. It has been confused in that area, however, 

with at least two older fossil species from Iceland, 

C. tjornesensis, n. sp., and G. breidavikensis, n. sp., and 

with the late Pleistocene and Kecent G. pseudislandica. 

another migrant from the Pacific.

G. tjornesensis occurs in both the "Mactra" and "Cardiuni''1 [Serripes] zones of Iceland; Askelsson (1960) indicated that the Pliocene-Pleistocene boundary is 

between the Mactra and Gardium zones. G. breidavikensis occurs in the uppermost fossiliferous 'bed of the 

Breidhavik sequence at Tjornes, Iceland, a horizon 

within the early part of the glacial Pleistocene.

G. breidavikensis is the only one of these Icelandic 

species that resembles G. islandica, but it has many more 

ribs than the latter. Furthermore, the anterior ear of 

the left valve more nearly resembles that of G. harnieri 

Altena (pi. 24, fig. 6) and G. tauroperstriata (Sacco) 

(1897, pi. 1, figs. 20, 21), species related to G. multistriata (Poli) from the Mediterranean. Sacco (1897, p. 9) 

though G. Islandica diverged from G. multistriata in 

post-Pliocene time. I am inclined to believe that G. 

breidavikensis belongs to the C. tauroperstriata group, 

but I have not seen any specimens that convince me that 

C. islandica is derived from G, breidavikensis. G. islandica appears to be much more closely related to some 

early Pleistocene forms in the Pacific.

Koger (1939, p. 168, pi. 22, figs. 3, 4) figured a specimen from Sicilian (early glacial Pleistocene) beds of 

Sicily that is very similar to the two Pacific early 

Pleistocene subspecies, G. i kanagae and G. i. powersi. 

The Sicilian occurrence is both the earliest in Europe 

and the most southern. Presumably the species reached 

the Mediterranean region from the Arctic, but the exact 

route is not clear; the species is not known in early 

Pleistocene beds in either England or the Netherlands.

It did not survive the early Pleistocene in the Mediterranean region.

A living variant of G. islandica, (pi. 24, figs. 12, 13) 

from northern Iceland has some resemblance to both the 

typical form and G. i. kanagae. Its ribs, while slightly 

coarser than in either of these forms, are not as coarse 

as in G. pseudislandica and G. wainwrightensis, nor is 

its left valve more inflated as in C. wainwrightensis.

Typical G. islandica occurs in late Pleistocene (or 

postglacial) beds at Bohuslan, Sweden, at Keykjavik, 

Iceland (pi. 18, fig. 8; pi. 19, figs. 2, 5), and probably in 

Greenland and northern Canada. All northern Atlantic records for G. islandica however, need, to be reexamined. Kecent specimens from eastern North 

America show clearly and consistently that two distinct 

species are involved: one species with fine nonbif urcating ribs on both valves lives from Newfoundland northward; another species with coarse bifurcating ribs on 

the right valve and inequisized ribs on the left valve lives 

along the coast of Maine and Massachusetts. A specimen of the latter from Eastport, Maine, was figured by 

Grant and Gale (1931, pi. 11, figs, la, b); in my opinion 

this is typical G. pseudislandica. MacGinitie (1959, 

p. 155) mentioned a specimen with broad primary ribs 

that divide from Vads0, Norway, suggesting that G. 

pseudislandica is living on both sides of the Atlantic. 

The same species occurs in the Clyde beds (late Pleistocene) of Scotland (Wood, 1851, pi. 5, fig. 1). Kichards 

(1962) recorded G. islandica from beds of late Pleistocene and postglacial age from Labrador to Long Island, 

but it now seems likely that both G. islandica and G. 

pseudislandica are included among the forms so 

identified.

Figured specimens: The specimens here figured are numbered 

USNM 645007-645009, 637761, 637762.

Locality of figured specimens: Raised terrace deposits (postglacial; radiocarbon dated at 10,200 yrs B.P.), Reykjavik Airport, Iceland, USGS M2055.

Doubtful identifications: Two specimens that may represent 

an undescribed subspecies of C. islandica are from the Recent 

beach at Tjornes, northern Iceland, USGS M2464.

Chlamys (Chlamys) islandica thulensis MacNeil, n. subsp. 

Plate 18, figure 2

Discussion. The form so named comes from late 

Pleistocene deposits of northern Greenland. It is distinguished from typical G. islandica by weak fascicles 

which, toward the beak, become single ribs that are 

higher and stronger than the adjacent riblets.

While this may be just an individual variation of G. 

Lslandwa, it is intermediate morphologically and geographically between typical G. islandica and G. islandica 

albida. It has some resemblance to G. i. kanagae. 

More specimens from this locality will have to be ex-
SYSTEMATIC PALEONTOLOGY 35

amined before its validity as a subspecies can be confirmed. Several scraps of other individuals have similar f asciciles.

Holotype: USNM 645010, an incomplete left valve, has a 

greatest dimension of 81 mm.

Type locality: Raised beach, probably postglacial, Narssurssuk, northwestern Greenland, USGS D386.

Chlamys (Chlamys) islandica kanagae MacNeil, n. subsp.

Plate 13, figure 6; plate 15, figure 3; plate 17, figures 1-8; 

plate 18, figure 1

Pecten n. sp. B. aff. P. albidus, MacNeil in Fraser and Barnett, 

1959, U.S. Geol. Survey Bull. 1028-1, p. 218.

Description. Shell of medium size, subrounded, 

medium inflated. Ears similar or slightly shorter than 

in typical C. islandica. Sculpture of right valve ranging from uniformly nonplicate or nonfasciculate to 

moderately fasciculate; fascicles are flat topped and 

bear from three to six riblets; interspaces are concave 

and shallow, about the same width as the fascicles, and 

contain from three to six riblets. Left valve ranges 

from moderately strongly fasciculate to weakly fasciculate; some fascicles or plicae are rounded and solid, 

dividing weakly near the margin; some fascicles are 

moderately high and divided into three to four riblets 

throughout most of their length; other fascicles are 

narrow and low, with a single riblet along the crest; 

interspaces are moderately broad and may contain from 

four to nine riblets that may be of subequal size or 

divided into secondary and tertiary series. Eiblets of 

both valves are finely beaded or scabrous, the closely 

set scales adding considerably to the apparent thickness. 

Microsculpture of adults nonreticulate and where seen 

consists of very fine straight radial lines. Some juvenile left valves have reticulate or metal lathelike microsculpture over the riblets and interspaces alike; this 

microsculpture terminates abruptly in the late juvenile 

stage and is followed by radial microsculpture.

Discussion. Some of the variants of this subspecies 

approach C. pseudislandica plafkeri. Right valves have 

similar flat-topped fascicles, and many left valves have 

moderately large smooth primary ribs or plications. 

The riblets of C. i. kanagae are finer and more scabrous, 

however, and the primary interspaces or interplicae of 

the left valve have more riblets. One specimen (pi. 13, 

fig. 6) from the upper part of the Middleton Island 

section is tentatively identified as C. i. kanagae.

G. islandica poioersi from Pleistocene beds on Amchitka is undoubtedly the closest known relative of C. 

i. kanagae. The shell of C. i. poiversi tends to be more 

inflated and twisted, and the riblets are finer, more 

widely spaced, and less scabrous. The two living Pacific 

subspecies of C. islandica, C. i. albida (Dall) (see

Arnold, 1906, pi. 52, figs. 2, 2a) from Unalaska and 

C. i. erythrocomata (Dall) (pi. 21, figs. 8, 9) from the 

Okhotsk Sea probably are descended directly from the 

G. i. kanagae-powersi stock. All these forms have similar microsculpture, reticulate in juveniles and finely 

radial in adults.

Of all the known Pleistocene pectinids in the Pacific, 

G. i. kanagae is the most likely ancestor of typical G. 

islandica. The typical form of C. islandica has no fascicles and the riblets are subequal in size. G. i. thulensis 

(pi. 18, fig. 2), here described from late Pleistocene or 

postglacial beds of Greenland, has weak fascicles, however, and it is intermediate both morphologicaly and 

geographically between C. i. kanagae and G. islandica 

islandica.

Types: The holotype (USNM 645011), a right valve, measures 73 mm in height and 67.5 mm in length. The paratype 

(USNM 645012) is a left valve. Other figured specimens are 

numbered USNM 645013-645021.

Type locality: Green tuffaceous sandstone along west side of 

the northeastern peninsula of Kanaga Island, north of coastal 

lakes and about 4.5 miles south southwest of Kanaga Volcano, 

ceneral Aleutian Islands, USGS D3.

Other occurrences: Unnamed Pleistocene formation on Adak 

Island, central Aleutian Islands, USGS 16907; upper part of 

section (early Pleistocene) on Middleton Island, Alaska, USGS 

M1742.

Chlamys (Chlamys) islandica powers! MacNeil, n. subsp. 

Plate 16, figures 1, 2, 4-7

Discussion. This subspecies is closely related to G. i. 

kanagae. It differs from it by having a more inflated 

shell and a slight twist to the shell. The riblets of the 

left valve are smaller, more delicate, and more widely 

spaced in G. i. poiversi, and the riblets of the right valve 

are correspondingly larger and broader. While both 

subspecies have fascicular bundles or plications on the 

left valve, the range of variation differs; C. i. kanagae 

has variants with fused riblets of moderately broad 

solid ribs, and even the most weakly fasciculated specimens have a heavier riblet along the crest of the fascicle; 

G. i. powersi has little or no tendency for the riblets to 

be fused or enlarged on the fascicles. Both subspecies 

have similar microsculpture.

While it will not be possible to describe the exact line 

of descent of this and the other subspecies of C. islandica 

until the complete range of variation of all intermediate 

forms is known, it seems fairly certain that this subspecies and C. i. kanagae are two of the oldest known 

forms that can be included in G. islandica. They are 

clearly related to the late Pliocene forms here referred 

to G. cosibensis, G. picoensis chinkopensis, and C. JianaisMensis. All these species and subspecies are variable, 

but it is still not possible to say which variants are more 

primitive, which are more advanced, which species are
36 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

successional, or which are coderivatives from older 

varietal series.

This subspecies probably is the closest known fossil 

relative of 0. i. albida (Dall) and C. L erythrocomata 

(Dall).

Types: The holotype (USNM 645022), a right valve, measures 

96 mm in height and 86 mm in length. Two para types (USNM 

645023, 645024) are left valves. Three other figures specimens 

are numbered USNM 645025-645027.

Type locality: Poorly bedded loose sand and gravel forming 

a fill about 75 ft thick at the head of South Bight, Amchitka 

Island, Aleutian Islands, USGS D46. Possibly from an upper 

horizon in the section (middle Pleistocene?).

Chlamys (Chlamys) islandica erythrocomata (Dall) 

Plate 21, figures 8, 9

Peoten (Chlamys) erythrocmnatus Dall, 1907, Smithsonian Misc. 

Colln., v. 50, pt. 2, p. 170.

Discussion. The photographs reproduced here are 

the first illustrations of the holotype of this species to 

be published. They were sent to Dr. L. G. Hertlein, of 

the California Academy of Sciences, by Dr. Paul 

Bartsch, of the U.S. National Museum, several years 

ago. I do not believe any subsequent reference to this 

species by either an American or Japanese author is 

correct. H. A. Kehder (written commun., Grau, 1959, 

p. 73) thought from an examination of the holotypes 

that C. i. albida and C. i. erythrocomata were close 

enough to be united; certainly they are very close.

The species figured by Kotaka (1962, pi. 34, figs. 18- 

23) from the Okhotsk Sea as C. islandica erythrocomata 

has a weakly inflated right valve, and the anterior 

dorsal margin is longer than the posterior dorsal margin. This form is closest to C. ivaimvrightensis, here 

described. Unless a careful comparison should justify 

a new subspecific name, it probably should be referred 

to that species.

As far as I can determine, this subspecies has not been 

found since the original discovery, and, like C. i. albida, 

it is a rare form.

Holotype: The holotype (USNM 110462) measures 69 mm in 

height and 70 mm in length.

Type locality: Recent. Albatross Sta. 5021, Okhotsk Sea.

Chlamys (Chlamys) islandica albida (Dall) 

Not figured

Pecten (Chlamys) hericius var. albidus Dall, MS., 1904 (cited

in Arnold, 1906, p. 136). 

Pecten (Chlamys) hastatus var. albidus Dall in Arnold, 1906,

U.S. Geol. Survey Prof. Paper 47, p. 136, pi. 52, figs. 2,

2a. 

Peoten (hericius Gould var.?) albidus, Oldroyd, 1924 [1925],

Stanford Univ. Pubs., Geol. Ser., v. 1, no. 1, p. 52, pi. 12,

figs. 8, 9. 

Pecten (Pecten) hastatus albidus, Grant and Gale. 1931, San

Diego Soc. Nat. History Mem., v. 1, p. 168.

Chlamys islandica albida, Grau, 1959, Allan Hancock Pacific 

Bxpd., v. 23, p. 72, pi. 23, fig. 1.

Discussion. Grau combined this eastern Aleutian 

subspecies with C. i. erythrocomata from the Okhotsk 

Sea. While these two forms are more closely related 

to one another than either is to any other known form, 

I prefer to regard them as separate subspecies. C. i. 

erythrocomata, judging solely from the illustrations of 

the holotype (pi. 21, figs. 8, 9), is more elongate and the 

byssal notch is deeper and more angulate. C. i. albida 

is higher and the byssal notch is shallower and less 

angulate. The specimen of C. i. albida figured by Grau 

has the same height in proportion to its length and the 

same type of byssal notch as the holotype; it shows a 

small amount of variation, however, in the number and 

spacing of the fascicles. In all probability both subspecies are descended directly from C. i. powersi.

Holotype: USNM 150207, has a height of 45 mm.

Type locality: Recent, Illiukliuk Harbor, Unalaska Island, 

eastern Aleutian Islands, Alaska.

Other occurrences: Albatross sta. 3322, off Markoffski Bay 

(Grau) ; probably Morkovskoi Bay, now known as Pumicestone 

Bay, west side of Unalaska Island.

Other species assigned to Chlamys

Chlamys sp. 

Plate 14, figure 3

Discussion. The impression of an incomplete left 

valve from the upper beds on Middleton Island is unlike 

any of the other pectinids found there. Its narrow but 

well-defined fascicles and fine riblets suggest a relationship to C. islandica Jcanagae and G. i. powersi. Until 

better specimens of this form are obtained, it would be 

difficult to determine its relationships more precisely. If 

this is a subspecies of 0. isldndica, it is the only record 

of the species in a section in which fossiliferous beds of 

both Pliocene and Pleistocene age are recognized.

Figured specimen: USNM 645028, a fragment of a left valve, 

has a longest dimension of 55 mm.

Locality of figured specimen: Unnamed formation, upper beds 

(horizon probably early Pleistocene), Middleton Island, Alaska, 

USGS M1742.

Chlamys (?) washburnei (Arnold) 

Plate 1, figure 2

Pecten (Chlamys) ivashburnei Arnold, 1906, U.S. Geol. Survey 

Prof. Paper 47, p. 119, pi. 45, fig. 2.

Chlamys ivashburnei, MacNeil in Powers, Ooatsi, and Nelson, 

1960, U.S. Geol. Survey Bull. 1028-P, p. 537.

Discussion. Very little concerning the age of this 

species can be added to my previous statement (MacNeil 

in Powers and others, 1960, p. 537) that "CJilamys 

washburnei was described from beds on the Yachates
SYSTEMATIC PALEONTOLOGY 37

River, Oregon, which have been assigned variously to 

the Pliocene (Arnold, 1906, p. 119-120), middle 

Miocene(?) (Weaver, 1942, p. 86), and to the early 

Oligocene (Vokes, personal commun., 1954). It is associated, according to Vokes, with two crinoids, 

Isocrinus oregonesis and1 /. nehalemensis, which Moore 

and Vokes (1953, p. 116) described from beds correlated 

with the Keasey Formation (early Oligocene)."

Chlamys washbuifyiei and Isocrinus oregonensis occur 

together on Kat Island in the Aleutians (MacNeil in 

Lewis and others, 1960, p. 560). The specimen figured 

here is from nearby Amchitka Island, presumably from 

beds of the same age as those on Eat Island. A poorly 

preserved mold from the south side of Attu Island may 

be the same species.

Chlamys washburnei is one of the earliest members of 

the O. islandica group, and it could be the radicle for 

several subsequent genera, including Placopecten.

Nagao (1928, p. 39) described Pecten (Chlamys} 

ashiyaensis from late Oligocene beds of Japan. Illustrations of this species by Oyama, Mizuno, and Sakamoto (1960, pi. 28) strongly suggest that this is a 

Vertipecten, or at least a Chlamys very closely related 

to Vertipecten. Masuda (1962b, p. 179) decided, after 

studying Nagao's specimens, that two species were involved. The second species was named Chlamys nagaoi 

Masuda. His figures of the species (1962b, pi. 20, figs. 

4-6) show it to be very similar to O. washburnei. Both 

the Alaskan and Oregon beds containing C. washburnei 

are believed, however, to be older than late Oligocene, 

the age assigned to the Japanese species.

Another species that probably is related to C. ivashburnei was described by Makiyama (1934, p. 133, pi. 3, 

figs. 7, 8) from the Asagai Formation (late Oligocene 

and early Miocene) at Matchgar, northern Sakhalin as 

Chlamys ma.tchgarensis. This species has heavier and 

broader ribs than C. loashbumei.

Types: The holotype (USNM 164843) has a height of 108 mm. 

Figured specimen numbered USNM 645029.

Type locality: Mouth of Yachates River, Lincoln County, 

Oreg., in beds now referred to the Keasey Formation (horizon 

probably early Oligocene), USGS 3593.

Locality of figured specimen: Banjo Point Formation 

(Oligocene?), south side of Amchitka Island at 51°24'32" N., 

179° 09'44" E., Aleutian Islands, Alaska, USGS D47.

Other occurrences: Gunners Cove Formation (Oligocene?), 

Rat Island, Aleutian Islands, Alaska, USGS M337; volcanic conglomerate along Nevidiskof Bay, south side of Attu Island, 

Aleutian Islands, Alaska (49-P-67).

?Chlamys sp. 

Plate 6, figure 9

Discussion. An unidentified fragment of a pectinid 

is present in a collection of possible early Miocene age 

from Tanaga Island in the central part of the Aleutian

Islands (Fraser and Barnett, 1959, p. 220-221, loc. 12). 

It occurs in association with a large Spondylusl, resembling 8. perrini Wiedey, Platyodon sp., Acmaea sp., 

and a large heavily fluted barnacle that according to V. 

A. Zullo (oral commun., 1962) is wholly unlike any 

known northern Pacific barnacle.

The fragment, probably of a right valve, bears some 

resemblance to a fragment of Patinopecten (Lituyapecten) poulcreekdnsis MacNeil figured by me (McNeil, 

1961, pi. 35, fig. 4), and it is of comparable age.

Figured specimen: USNM 645030, a fragment of a right valve, 

measures 36 mm in its longest dimension.

Locality of figured specimen: A 5 to 20-foot lens of tuffaceous 

coquina conglomerate overlying an andesite flow, Tanaga Island, 

lat 51°41'25" N., long 177°50'30" W., Aleutian Islands, USGS 

D26 (T).

Chlamys? nuwokensis MacNeil 

Plate 6, figures 1-3

Chlamys nuwokensis MacNeil, 1957, U.S. Geol. Survey Prof. 

Paper 294-O, p. 120, pi. 11, figs. 4-6,12.

Discussion. This species has a very thin translucent 

shell. The umbonal angle is narrow but flares rapidly, 

making the dorsal margins strongly concave. The ribs 

are narrow with a rounded top in juveniles but they become indistinct towards the margin in adults; the point 

at which they become indistinct varies in different individuals. The interspaces are broad and gently rounded, and they are sculptured with fine radial riblets. The 

surface is finely scabrous but not with the metal-lathe 

type of microsculpture. The byssal sinus is moderately 

deep and the byssal area of the anterior ear of the right 

valve is wide.

The relationships of this species are unknown. As 

pointed out at the time of its description, it has at least 

a superficial resemblance to OJilamys sayana (Dall) 

from the middle Miocene of Florida (see Tucker-Row - 

land, 1938, pi. 2, fig. 6). Nothing described from the 

northern Pacific area thus far has much resemblance to 

it. The species has a vague similarity to some variants 

of C. opercularis (Linne) from nothern Europe but not 

enough for definite identification.

Pecten glyptus Verrill (Dall, 1889, p. 248, pi. 8, figs. 

2, 3; Abbott, 1954, p. 366, pi. 33, fig. a), a Recent species 

from moderately deep water in the western Atlantic, has 

a thin shell with somewhat similar shape and sculpture. 

Dall's figure shows, however, that it has well-defined 

Amusium-like internal ribs. C. nuivokensis has not the 

slightest indication of internal ribs; the interior surface 

undulates gently in conf ormance with the exterior ribs.

There is at least a superficial similarity between C. 

nuiookensis and C. hastata. Both species have very concave dorsal margins and sharp-crested ribs separated
38 CENOZOIC PECTESTIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

by broad rounded interspaces. Furthermore, the interspaces are sculpture by moderately fine regular radial 

riblets. I am inclined to regard1 whatever similarity 

there is between these forms as liomeomorphic.

If and until it can be shown that this species is clearly 

related to some Tertiary form, it might be suspected of 

being a relict of some very old group. It has as much 

resemblance to Pecten assiniboiensis Landes (1940, p. 

142, pi. 3, fig. 9) from the Bearpaw Formation (Cretaceous) of Saskatchewan as to the above-mentioned Tertiary and Recent species. The possibility exists that there 

was a landlocked or nearly landlocked sea in the polar 

region throughout early Tertiary time.

Types: The holotype (USNM 561866), an incomplete left valve, 

has a length of 60 mm. Two paratypes are figured, a fragment 

of a left valve (USNM 561867), and a fragment of a right valve 

(USNM 561869).

Type locality: Beds below the type Nuwok Formation of Ball 

(1919) (210-258 ft below the top of the Nuwok Formation, the 

upper 210 ft of which constitutes the type Nuwok), Carter Creek, 

a stream flowing into Oamden Bay, northeastern Alaska, USG-S 

D50 (T). The horizon is believed to be of middle or late Miocene age (see remarks under Arctinula groenlandica, p. 8).

Genus VERTIPECTEN Grant and Gale, 1931

Pecten (Vertipecten) Grant and Gale, 1931, San Diego Soc. Nat. 

History Mem., v. 1, p. 188.

Type species (by original designation): Pecten nevadanus Conrad. Early and middle Miocene. Southern 

California.

Discussion. The outstanding peculiarity of Vertipecten is the much greater inflation of its left valve over its 

right valve. This characteristic is rare but not unknown 

in other pectinids; Vertipecten certainly seems to be the 

largest pectinid to have it.

While the more advanced species of Vertipecten have 

highly inflated left valves and very coarse ribs, rivaling 

Patinopecten in coarseness, the earliest and more primitive species had less inflated left valves and finer ribs. 

The more finely ribbed Vertipecten are clearly related to 

Chlamys, and the genus appears to have diverged from 

Ghlamys in late Eocene or early Oligocene time. The 

known Vertipecten that have fine ribs and that appear 

to be most closely related to Chlamys are of Oligocene 

and possibly earliest Miocene age. Species with medium 

to moderately coarse ribs also occur in Oligocene beds, 

however, suggesting that coarsely ribbed stocks appeared early in the evolution of the genus and that both 

fine and coarsely ribbed stocks were coexistent for a 

time. The last known species of Vertipecten have coarse 

ribs. Left valves of Vertipecten usually have finely 

reticulate or metal lathelike microsculpture, as do most 

groups of Chlamys.

Ghlamys grunskyi (Hertlein) (new name for Pecten 

Iranneri, Dickerson, 1917, pi. 28, fig. 2), from the Gries

Ranch Formation (early Oligocene), near Vader, Wash., 

is closely related to Vertipecten and may actually be a 

Vertipecten. Only the right valve of this species has 

been found. G. grunskyi is one of the closest known 

relatives of V. lachenbruchi here described, from middle 

Oligocene beds of Alaska.

Weaver and Kleinpell (1963, p. 197) identified Pecten 

(Ghlamys} sespeensis Arnold, a Vaqueros species, in 

both the so-called Coldwater Sandstone (late? Eocene) 

and the upper part of their Gaviota Formation (?horizon middle Oligocene) of southern California. One of 

the specimens they figured (pi. 29, fig. 10, pi. 30, fig. 1) 

from the Graviota Formation is very close to the boundary between Chlamys and Vertipecten, morphologically. 

Weaver and Kleinpell (1963, p. 198) also recorded Vertipecten yneziana (Arnold) from early (?) to late Oligocene beds in the same region. This is certainly a Vertipecten^ and I see 110 reason to doubt the specific 

identification.

At the same time, Weaver and Kleinpell (1963, p. 

198, pi. 31, figs. 2, 3, 7) described a new subspecies, Pecten (Vertipecten} yneziana subyneziana which they recorded from both the so-called Coldwater Sandstone 

(late? Eocene) and the undifferentiated Sacate-Gaviota 

Formation (late Eocene or early Oligocene). They say, 

"With this previously undescribed subspecies the very 

phylogenetic radicle of the subgenus Vertipecten, as described by Grant and Gale (1931, p. 188-189), is now 

recognized." Unless Vertipecten as presently construed 

is polyphyletic, I am inclined to doubt this conclusion. 

Assuming the age assigned to this subspecies is correct, 

it does not conform morphologically to what I would 

expect the prototype species of Vertipecten to be. It is 

possible, of course, that Vertipecten is polyphyletic and 

that finely ribbed species such as V. porterensis 

(Weaver) and coarsely ribbed species such as V. fucanus 

(Dall) belong to different genera.

If Vertipecten as presently construed is polyphyletic, 

the coarsely ribbed type probably had a much earlier 

origin than the finely ribbed type. A possible ancestor 

of the coarsely ribbed type might be found in Pecten 

(Chlamys} -fissicosta Etheridge (Woods, 1902, p. 163, 

pi. 30, figs. 3-8) from the Cretaceous of England. According to Woods, the right valve of this species is less 

inflated than the left valve. If and until some intermediate forms are discovered, and it can be shown 

how this stock might have reached the northern Pacific, 

this possible relationship is little more than an interesting speculation.

The genus Vertipecten is peculiar to western North 

America. The fact that no member of this group has 

been found on the Asiatic side of the Pacific is in harmony with the thesis that few, if any, mollusks having
SYSTEMATIC PALEONTOLOGY 39

pelagic larvae have migrated from the American to the 

Asiatic side of the Pacific. In contrast, many Asiatic 

forms have migrated to the American side. Such a 

distribution for forms with pelagic larvae may result 

from the major oceanic current circulation, which is 

clockwise in the northern hemisphere. The Subarctic 

Current of Bering Sea circulates counterclockwise, and 

it could carry some pelagic larvae towards East Asia by 

a far northern route, but so far little is known of such 

migrations. The few mollusks that appear definitely 

to have originated on the American side of the Pacific 

and to have appeared subsequently in East Asia have 

benthonic larvae. These forms, while having a temperature preference that may restrict them to a current 

or other water of favorable temperature, may, nevertheless, migrate with or against currents.

Vertipecten lachenbruchi MacNeil, n. sp. 

Plate 1, figures 3-8; plate 2, figures 4, 7

Description. Shell of medium size and moderately 

inflated, the left valve more inflated than the right, valve; 

beaks moderately sharp; dorsal margins weakly concave; hinge line moderately long and straight. Ears 

prominent and moderately broad; anterior ear of right 

valve moderately broad with a broad strongly sculptured byssal area, byssal notch broad but moderately 

shallow; posterior ear of right valve moderately long 

with a concave moderately sloping posterior margin; 

anterior ear of left valve with a weakly concave but 

nearly vertical anterior margin; posterior ear of left 

valve moderately short and strongly sloping along its 

posterior margin. Sculpture consisting of moderately 

small and closely set ribs that are variable in shape and 

spacing and ornamented with beadlike to scabrous projections; left valve (holotype) with a maximum of 47 

ribs, of which about 20 might be considered primaries, 

the secondaries are variable in size and in the number 

between pairs of primaries; right valve ribs sharper 

and irregularly paired, especially near the beaks, scabrous to bluntly spined; ears strongly sculptured with 

primary and secondary riblets, growth lines on byssal 

area strongly raised and irregular.

Discussion. This species is based on specimens from 

two localities, the holotype, a left valve and the largest 

specimen, from McGinty Point on the mainland, and 

several scraps of right valves from Unga Island. Acila 

shumardi occurs at both localities.

I cannot say on the basis of the material at hand 

whether this species is very close to any others described. 

Its sculpture resembles that of Pecten (Chlanvys] proavus Arnold (1906, p. 52, pi. 2, figs. 6-8) from a locality 

between Pescadero Creek and the San Lorenzo River, 

San Mateo County, Calif. Arnold thought its age was

Eocene, but Keen and Bentson (1944, p. 93) said "Oligocene or Miocene." Earl Brabb, of the U.S. Geological Survey (oral commun., June 8, 1964) thought the 

horizon of P. proavus was within the Zemorrian foraminiferal stage.

V. lacheribruclii may be fairly closely related to Pecten (Ghlamys) grunskyi Hertlein (Pecten branneri, 

Dickerson, 1917, pi. 28, fig. 2) from which it differs 

mainly by having weak spines or scales on its ribs. The 

ears of the right valve are very similar on the two 

species.

Types: The holotype (USNM 645031), an incomplete left 

valve, has a length of 58 mm and if complete probably would be 

about 80 mm. Three para types (USNM 645032, 645033, 645034) 

are smaller fragmental right valves. Two figured scraps are 

numbered USNM 645035 and 645036.

Type locality: An unnamed formation within and possibly 

near the top of the Acila, slmmardi zone (middle Oligocene), east 

tributary to Mud Bay, south of Port Moller, Alaska Peninsula, 

USKJS M1025.

Other occurrences: Paratypes and figured specimens are from 

an unnamed formation south of West Head, northeastern Unga 

Island, Alaska, probably the same stratigraphic horizon as the 

type locality near Mud Bay, USGS '5037.

Vertipecten popofensis MacNeil, n. sp. 

Plate 1, figure 1; plate 2. figures 1, 3, 5, 6, 8

Description. Shell of medium size and moderately 

thin. Left valve more inflated than right valve, 

especially near the beak. Anterior ear of left valve 

larger than posterior ear, anterior margin weakly 

S-shaped, posterior ear with a convex margin, ears of 

right valve not well known, anterior ear broad with a 

broad byssal area. Left valve sculpture consists of moderately broad rounded ribs over most of the disc; the 

ribs become smaller and weakly beaded posteriorly. 

Weaker interstitial ribs present in some interspaces on 

the disc and in most posterior interspaces. Right valve 

with low rounded to flattened ribs and interspaces of 

nearly equal width; posteriormost ribs weak and irregular. Reticulate or metal lathelike microsculpture 

present on ears, the upper part of the disc, and persisting to the margin on the posterior part of the shell, 

posteriorly having a diagonal strike as in Caniptonectes.

Discussion. Although the material on which this 

species is based is fragmental and the fragments belongto different individuals, it is presumed that the fragments all belong to the same species. Several nearly 

complete internal molds are present in the same 

collections.

The shell of this species is thin for a pectinid of this 

size, a factor contributing to the rarity of large pieces 

of test; the fragments figured were freed from matrix 

in the laboratory. The test apparently crumbled and 

was lost on free specimens collected in the field.
40 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Vertipecten popofensis is probably most closely related to two Miocene species, V. fucanus (Dall) from 

the Astoria Formation of Washington and V. ~bowersi 

(Arnold) (= V. nevadanus (Conrad)) from the Temblor Formation of central California (for both see 

Arnold, 1906). This group of Vertipecten has moderately strong to strong ribs; the ribs of the right valve 

are broadly rounded or flat topped. V. porterensis 

(Weaver) (see Clark and Arnold, 1923, pi. 24, fig. 1), 

from the Blakeley Formation of Weaver (1912) (late 

Oligocene and early Miocene) of Washington, appears 

to belong to a different group of Vertipecten, a group 

that is more primitive morphologically and that retains 

more of the characters of the ancestral Chlamys. 

V. porterensis is more closely related to V. lachenbruchi 

and may be derived from that species.

The oldest known Vertipecten, V. yneziana (Arnold) 

(see Weaver and Kleinpell, 1963, pi. 30, fig. 7; pi. 31, 

figs. 1, 4), and V. sespeensis (Arnold) (ibid., pi. 29, fig. 

10; pi. 30, fig. 1), both from late Eocene or early Oligocene beds of southern California, may also represent two 

groups; V. sespeensis the group of V. porterensis, and 

V. yneziana the group of V. fucanus.

V. popofensis occurs in association with Acila shumardi (Dall), Ostrea tigiliana Slodkewitsch, Area cf. 

A. merriami (Van Winkle), and numerous other probably undescribed species.

A fragment of a pectinid (pi. 1, fig. 1) from the upper 

part of the Tokun Formation (Eocene and Oligocene) 

in the Katalla district, Alaska, may be referable to V. 

popofensis. The specimen is an internal mold with a 

little shell material adhering; it does not show the external character of the ribs. The horizon in the Oligocene from which this fragment was obtained may be 

older than the horizon of the type of V. popofensis.

The species of Vertipecten here described are the first 

undoubted Vertipecten to be reported thus far from 

Alaska. Some internal molds from the Yakataga district reported previously (MacNeil, 1961, p. 236) may be 

a Chlamys related to Chlamys tugidakensis, here described. Vertipecten may have originated in Alaskan 

waters.

Types: The holotype (USNM 645037), an incomplete left 

valve, measures 48 mm in its longest preserved dimension; it is 

a half-grown specimen. The paratype from the same locality 

(USNM 645038), a large fragment of the disc of a left valve, 

would have a restored length of about 90 mm. Two paratypes 

and two figured specimens are numbered USNM 645039, 645041, 

645051.

Type locality: An unnamed formation within the Acila shumardi zone (middle Oligocene), seacliff near the northwest 

corner of Popof Island, Shumagin Islands, Alaska, USGS 3563.

Other occurrences: Same horizon, northeastern Unga Island 

south of West Head, USGS 5037.

Doubtful occurrence: Upper part of Tokun Formation, "Split 

Creek, 100-200 yards above branch that heads against the Bedwood Creek divide," Katalla district, USGS 4323.

Vertipecten n. sp.? 

Plate 2, figure 2

Discussion. A mold of a left valve of a Vertipecten is 

present in one of the collections of the Harriman Expedition from the east side of Chichagof Bay, a small cove 

on the south side of the Alaska Peninsula, west of 

Stepovak Bay and about due north of Korovin Island. 

It occurs in a partly metamorphosed rock containing 

Acila shwnardi, Ostrea tigiliana Slodkewitsch, Epitonium atwoodi Dall, and other mollusks.

The specimen appears, on the basis of its ribbing, to 

be intermediate between V. lachenbruchi and V. popofensis, possibly closer to the former. The interspaces 

have a reticulate or metal lathelike microsculpture. 

The ears are more coarsely ribbed than on either of the 

above species.

Figured specimen: USNM 164892, a fragment of a left valve, 

measures 47 mm along its most complete dimension. 

Locality of figured specimen: USGS 3373.

Genus PATINOPECTEN Dall, 1898

Patinopecten Dall, 1898, Wagner Free Inst. Sci. Philadelphia 

Trans., v. 3, p. 695.

Type species (by original designation) : Pecten 

caurinus Gould. Recent. California to Alaska.

Discussion. Prior to 1962, most of the large pectinids, Tertiary to Recent, on both sides of the northern 

Pacific were assigned to the genus Patinopecten. Then 

Masuda (1962b, p. 216) separated a group of Patinopecten-like species under the name Kotorapecten, and 

Akiyama (1962) proposed the name Masudapecten for 

three other species. Masuda (1963) decided that none 

of the Japanese species previously assigned to Patinopecten belonged to that genus, and for another large 

group of species he proposed the new genus Mizuhopecten, having as its type the Recent Pecten, yessoensis 

Jay. No Japanese species are retained in Patinopecten 

as a result of these revisions. Inasmuch as Masuda regarded Mizuhopecten, Kotorapecten, and Masudapecten 

as being more closely related to Fortipecten Yabe and 

Hatai than to Patinopecten and because Fortipecten 

was the oldest of the Japanese names, he proposed 

Fortipectininae as a new subfamily name to include 

the newly proposed genera. Nipponopecten Masuda 

(1962b,,p. 194) was also included in the Fortipectininae.

Masuda's classification, which is based on selected 

characters, does not relate the American Patinopecten 

to the Japanese forms. In my opinion, the status of 

the newly proposed Japanese genera and subfamily 

must be considered tentative until the exact relation-
SYSTEMATIC PALEONTOLOGY 41

ship of all the American and Japanese stocks is better 

understood than at present. The fact remains that the 

large American pectinids referable to Patinopecten and 

to the subgenus Patinopecten (Lituyapecten) MacNeil 

appeared in America abruptly and without any known 

American antecedents. In all probability, the stock 

or stocks came from East Asia. I find it difficult to believe that some of the species included under Mizuhopecten by Masuda will not be restored to Patinopecten 

or that Patinopecten will not have some suprageneric 

priority in a subfamily or family name.

Subgenus PATINOPECTEN Ball

Patinopecten (Patinopecten) cf. P. (P.) caurinus (G-ould) 

Plate 4, figures 3, 4

Discussion. Beds high in the Yakataga Formation 

in the vicinity of the Pinnacle Hills in the Malaspina 

district have been known to contain P. caurinus or a 

species closely related to it (Dall in Russell, 1891, p. 

1T1-1T3; MacNeil, 1961, p. 236; Miller, 1961, p. 243). 

The figures of this form given here are the first to be 

published. They are photographs of rubber casts obtained from molds prepared by the acid solution of shell 

material in slabs of a highly indurated sandstone. The 

shells themselves were deeply pitted by the enclosing 

sand grains so that little or no surface detail shows on 

the casts. The ears and ribbing, however, show that 

the species is very similar to P. caurinus.

Patinopecten caurinus has not been identified with 

certainty in pre-Pliocene beds; the supposed Miocene 

records of Grant and Gale (1931, p. 195) are based on 

P. propatulus Conrad and P. oregonensis Howe, which 

they placed in the synonymy of P. caurinus. The 

species has been found in the Coos Conglomerate (early 

Pliocene) of Oregon and in the Rio Dell Formation of 

Ogle (1953) (part of the Wildcat Series of Lawson, 

1894) (Pliocene) of Humboldt County, Calif. A specimen from the so-called Wildcat Series was figured by 

Masuda (1963, pi. 23, figs, la, b).

Figured specimens: The largest figured specimen (USNM 

645042), a right valve, has a height of 94 mm and a length, 

slightly compressed, of 96 mm. A left valve is numbered USNM 

645043.

Locality of figured specimens: Yakataga Formation, upper 

part (horizon probably Pliocene), south side of Point Glorious 

at the western end of the Pinnacle Hills, a spur projecting into 

the eastern side of Seward Glacier. Malaspina district, Alaska, 

USGSR263 (T).

Subgenus LITUYAPECTEN MacNeil, 1961

Patinopecten (Lituyapecten) MacNeil, 1961, U.S. Geol. Survey 

Prof. Paper 354-J, p. 227.

Type species (by original designation) : Patinopecten 

(Lituyapecten) lituyaensis MacNeil. Late Miocene(?). 

Lituya Bay district, Alaska.

Discussion. At one time (see MacNeil, 1961, p, 228) 

I did not feel that the origin of typical Patinopecten 

was clear; however, I have become convinced on the 

basis of further study that Patinopecten (Patinopecten) 

is derived from the older subgenus Patinopecten 

(Lituyapecten). The closest known relative of P. 

caurinus may be P. (L.) purisimaensis (Arnold).

It still remains to be shown how the American Patinopecten and Patinopecten (Lituyapecten) are related 

to the early so-called Patinopecten of Japan, all of 

which Masuda (1963) now places in different genera. 

I am not prepared to accept Masuda's (1963, p. 152) 

suggestion that Patinopecten is more closely related to 

typical Pecten and the Amusiinae than to the large 

Japanese pectinids or that it is a migrant from the 

Mediterranean region rather than from East Asia.

Patinopecten (Lituyapecten) n. sp. 

Plate 6, figures 6, 8, 10

Discussion. MacNeil, 1961, p. 231, pi. 41, fig. 2) 

figured a specimen from the Icy Point section at the 

south end of the outcrop of Tertiary beds in the Lituya 

district, Alaska, as Patinopecten (Lituyapecten) yakatagensis ? Clark. A few additional scraps of this species 

have been collected since that time. While these scraps 

indicate that a still-undescribed species lived in the area, 

they do not provide enough of the shell to justify a description. It is presumed that one of the scraps recently 

collected is part of a left valve, but, if so, the left valve 

does not have the frills along the edges of the ribs that 

characterize the other Alaskan species of Lituyapecten. 

This species closely resembles P. (L.) coosensis 

(Shumard).

Figured specimens: USNM 645044,-645046 are all scraps, two 

of them right valves and one a possible left valve.

Locality of figured specimens: Beds of probably late Miocene 

age in the vicinity of Icy Point, Lituya district, Alaska, USGS 

M1144, M1154, and M1842. A larger fragment figured previously 

is from USGS D187 (T).

Subgenus MIZUHOPECTEN Masuda, 1963

Mizuhopecten Masuda, 1963, Trans. Proc. Palaeont, Soc. Japan, 

new ser., no. 52, p. 151.

Type species (by original designation) : Pecten yessoensis Jay. Recent. Northern Japan.

Discussion. Masuda separated Mizuhopecten from 

Patinopecten because of its longer ears, much shallower 

byssal notch, and the lack of a distal denticle on its auricular crurae. He also states that Mizuhopecten has 

broader and more rounded ribs, but both groups are 

variable in that respect. The size of the ears and the 

depth of the byssal notch seem to be the most reliable 

charatcers for distinguishing typical Patinopecten and
42 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Mizuhopecten. The ears of the respective type species, 

P. caurinus and P. yessoensis, are joined to the dorsal 

margins somewhat differently; in P. caurinus the ears 

are flush with or even slightly raised above the margins, 

and there is no open cleft; in P. yessoensis the ears are 

set back from the margins, and there is a moderate cleft 

between the ears and margins.

Another character that seems to be consistent, one that 

Masuda did not mention, is the nature of the umbonal 

callus that fills the area between the muscle scar and the 

cardinal plate. P. caurinus has a thin callus that appears to be crystallographically more similar to the rest 

of the interior of the shell. P. yessoensis has a thick 

coarsely crystalline callus that shows numerous reflecting surfaces on individual crystals.

Patinopecten (Mizuhopecten) skonunensis MacNeil, n. sp. 

Plate 4, figure 2; plate 6, figure 7

Description. Only the right valve of this species is 

known. Shell of medium size, suborbicular, moderately 

inflated. Beaks moderately overturned, sloping moderately steeply toward the hinge. Dorsal margins very 

weakly concave, outer margins evenly curved. Hinge 

line of medium length and ears of medium size; anterior 

ear moderately broad with about three faint radial riblets, byssal area swollen and sculptured by growth lines 

only; posterior ear moderately broad, posterior margin 

sloping at about 45°, radial sculpture hardly discernible; 

byssal notch shallow; ears nearly flush with dorsal margins and with no open cleft between the ear and margin. 

Sculpture consists of about 20 moderately prominent 

radial ribs of variable width, some of the anterior ribs 

having a tendency to split; interspaces rounded and 

slightly narrower than the ribs. The shell of the holotype is slightly worn, but there appears to be no clearly 

defined microsculpture. Muscle scar of medium size. 

Area between muscle scar and hinge plate with a moderately heavy coarsely crystalline callus. Auricular 

crurae moderately strong, swollen distally, and diverging weakly from the hinge line terminally. Ligament 

pit with strong lateral ridges. No ctenolium.

Discussion. The ears of this species are appressed to 

the dorsal margins as in P. caurinus, but in practically 

all other characters it is more closely related to P. yessoensis. The posterior ear slopes even more than in 

yessoensis; in caurinus the posterior margin of the ear is 

nearly vertical.

Judging from available figures of Japanese species, 

P. skonunensis is most closely related to the P. hashimotoi group of Akiyama (1962, p. 115), particularly to 

the P. yamasakii subgroup. Both P. hashimotoi Akiyama (1962, pi. 2, figs. 1, 5) from the Nakatombetsu 

Formation (early? Pliocene) of Hokkaido and P.

yamasakii ninohensis Masuda (see Akiyama 1962, pi. 

5, fig. 2) from the Suenomatsuyama Formation (lower 

part,, probably late Miocene according to Haitai and 

Nisiyama, 1952) of northern Honshu resemble this 

species. Masuda (1963, p. 149), however, assigned these 

two species to different genera, P. hashimotoi to 

Mizuho'pecten and P. yamasakii to Kotorapecten.

Of the American species commonly referred to 

Patinopecten^ I am inclined to believe P. healeyi 

(Arnold) (1906, pi. 37, figs. 1, 2) from the Pliocene of 

California is most closely related to P. skonunensis. P. 

healeyi has a shallow byssal notch, the posterior margin 

of the posterior ear slopes strongly, and the umbonal 

callus is coarsely crystalline and thick. P. healeyi has 

two-parted ribs on its right valve, but this division into 

two ribs is restricted to the anterior ribs of P. 

skonunensis.

The deep byssal notch of P. caurinus indicates that 

typical Patinopecten is closely related to and probably 

descended from the older American subgenus Lituyapecten. P. healeyi and P. skonunensis have a shallow 

byssal notch, and in this respect, at least, they are more 

like Mizuhopecten.

Addicott (1965) identified a Nassarius found with 

P. skonunensis as N. whitneyi (Trask), a species described from the Briones Sandstone (early late Miocene) of central California and reported from supposed 

middle Miocene beds in the same area.

Holotype: UCLA 39474, an incomplete right valve, 

measures 72 mm in longest dimension; its complete 

length would be comparable.

Type locality: Skonun Point, about 5 miles east of 

Masset on the north coast of Graham Island, Queen 

Charlotte Islands, British Columbia, UCLA 4674. 

Skonun Formation (probably late Miocene). (See 

MacKenzie, 1916, p. 73.)

Genus FORTIPECTEN Yabe and Hatai, 1940

Pecten (Fortipecten) Yabe and Hatai, 1940, Tohoku Univ. Sci. 

Repts., 2d ser. (Geology), v. 21, no. 2, p. 149.

Type species (by original designation) : Pecten takahashii Yokoyama. Maruyama Formation (early Pliocene). Southern Sakhalin. Reported from several 

formations of early Pliocene age in Hokkaido and 

northern Honshu.

Discussion. Masuda (1962b, p. 222) is, so far as I 

am aware, the first author to raise Fortipecten to the 

rank of genus, and it is here so regarded. Masuda 

(1963, p. 149-150) proposed the new subfamilial name 

Fortipectininae to include all the so-called Patinopecten 

of Japan which he transferred to other genera. Fortipecten is characterized by a very large adductor muscle, 

and in this character alone it is very distinct from
SYSTEMATIC PALEONTOLOGY 43

Patinopecten. It is equally distinct on this basis from 

the other Japanese genera, Masudapecten, Kotorapecten, Mizuhopecten, and Nipponopecten, that Masuda 

included in the Fortipectininae. I am not convinced 

that Masudapecten, Kotorapecten, and Mizuhopecten 

are sufficiently removed from Patinopecten to be included in a different subfamily. If a subfamily name 

is required, I would prefer to place these four genera 

in a subfamily Patinopectininae. Fortipecten is so 

unique that, pending further knowledge of its ancestry, 

it could stand in a subfamily of its own. Fortipectininae would, of course, have priority as a subfamily 

name for the group of Fortipecten.

According to Ohinzei (1960, p. 68), Fortipecten takahashii occurs in beds of early and middle Pliocene 

age, and a new species, F. kenyoshiensis (ibid., p. 64), 

occurs in the Togawa Formation of late Pliocene age. 

Chinzei dated the Togawa Formation as late Pliocene, 

partly because it is overlain unconformably by Pleistocene beds. Masuda (1962b, p. 222), on the other hand, 

assigned both species to the early Pliocene (in a twofold division).

If the known Japanese Fortipecten are confined to 

the lower half of the Pliocene, the genus may be a 

migrant to Japan from elsewhere in the northern 

Pacific. The new species from Alaska described here, 

F. mollerensis, is believed to be of late Miocene age, 

and, as F. hallae (Dall), the genus is known from both 

near Nome, Alaska, south of Bering Strait, and at 

Kivalina, Alaska, north of Bering Strait, in beds of 

very late Pliocene or possibly earliest Pleistocene age. 

F. piltunensis (Khomenko) (see Slodkewitsch, 1938, 

pis. 39, 40, figs. 2, 3) was described from the SupraNutovo series of Sakahalin, beds believed by Eussian 

geologists to be of very late Pliocene age. Fortipecten 

may thus occur in Alaska in beds both older and younger 

than those of Japan.

Fortipecten mollerensis MacNeil, n. sp. 

Plate 4, figure 1; plate 5, figures 1, 6

Description. Shell large, thick, medium inflated, 

slightly elongate anteroposteriorly, hinge line moderately long. Ears of left valve large and moderately 

elongate, the anterior ear slightly larger, terminal margins nearly vertical, anterior margin of anterior ear 

slightly sinuous. Sculpture of left valve consisting of 

about 16 low, rounded, moderately broad ribs, separated 

by shallow, rounded interspaces nearly twice as broad 

as the ribs. No secondary riblete or microsculpture 

discernible on type. Interior of left valve with moderately deep, rounded grooves opposite ribs that extend

only a short distance from the margin, probably being 

filled with callus centrally. Adductor muscle scar very 

large and deep, probably made deeper than originally 

by the solution of an aragonitic attachment layer. 

Pedal retractor scar also large and deep. Subumbonal 

callus area well defined and sunken. Eight valve ears 

unknown. Sculpture consisting of moderately strong 

broad ribs that may range from rounded to flattened to 

medially grooved on the central part of the disc, and 

finer irregularly spaced ribs terminally; some terminal 

interspaces have a moderate interstitial riblet. The 

central ribs of the right valve are broader than the 

interspaces.

Discussion. This species has a shorter hinge than 

either F. takahashii or F. kenyoshiensis, the ribs are 

considerably stronger and broader, and there is no apparent tendency for every third or fourth rib to be 

stronger. There is no tendency for the ribs of F. mollerensis to form nodes or bumps at regular intervals as 

in the Japanese species and in F. hallae from Alaska. 

F. mollerensis and F. hallae both have wider and 

stronger ribs and a shorter hinge line than the Japanese 

species. If F. mollerensis has any fine radial markings 

between the primary ribs of the left valve, they are not 

visible on the type; it differs in this respect from the 

other known species of Fortipecten.

The antecedents of this species, and, for that matter, 

the origin of the genus Fortipecten remains unknown. 

There is at least a superficial resemblance between 

F. mollerensis and some large pectinids from the Miocene of the Vienna basin. One such species, Amusslopecten gigas pi-ana Schaffer (1910, pi. 22, figs. 1, 2) 

has very large ears and somewhat similar sculpture. 

The muscle scars are not figured. Eelationship is suggested between Fortipecten and both Pecten and Amussiopecten by the fact that the dorsal marginal areas of 

the left valve of both F. takaJiasJiii and F. hallae are 

more swollen than the dorsal central part of the disc. 

An outside origin for Fortipecten is only a possibility 

at present, however, and an early Tertiary Japanese 

origin cannot be ruled out entirely.

F. mollerensis occurs with Clinopegma cf. C. stantoni 

(Arnold), Turritella aff. T. sagai Kotaka, Acila cf. 

A. empirensis Howe, Cyclocardia, Siliqua, Spisula, 

Macoma., Panomya, and Mya. The fauna is dated, 

tentatively, as late Miocene.

Types: The holotype (USNM 645047), a left valve, measures 

118 mm in height and 125 mm in length. The paratype (USNM 

645048) is a fragment of a right valve.

Type locality: A small knob extending above the level of the 

Recent terrace on the south shore of Port Moller, approximately 

3 miles southeast of Point Divide, USGS M2131.
44 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

Fortipecten hallae (Ball)

Not figured

Pecten (Plagloctenium) hallae Ball, 1921, Nautilus, v. 34, p. 76. 

Pecten (Patinopecten) rhytidus Ball, 1921, Nautilus, v. 34, p.

77. 

Pecten (Aequipecten) hallae, Grant and Gale, 1931, San Diego

'Soc. Nat. History Mem., v. 1, p. 220. 

Pecten (Wertipecten) rhytidus, Grant and Gale, 1931, San

Diego Soc. Nat. History Mem., v. 1, p. 191. 

Pecten (Fortipecten) hallae, MacNeil in MacNeil, Mertie, and

Pilsbry, 1943, Jour. Paleontology, v. 17, no. 1, p. 86, pi.

12, figs. 1, 2 ; pi. 13, fig. 1. 

Patinopecten (Fortipecten) hallae, MacNeil in Hopkins and

MacNeil, 1960, U.S. Geol. Survey Prof. Paper 400-B, p.

B341.

Disscussion. The only available figures of this species (MacNeil and others, 1943) show the exteriors 

of two right valves and a left valve. The muscle scar 

is extremely large, and the shell has a thick subumbonal 

callus. The left valve is swollen both medially and 

along the dorsal margins, leaving shallow, broad, but 

distinct sulci both anterior and posterior of the medial 

area; it resembles Pecten (Pecten) in this respect. The 

shell is thick and it weathers soft and chalky with a 

silklike sheen. The left valve has fine radial riblets 

between the primary ribs and the surface retains remnants of a metal lathelike microsculpture.

Fortipecten hallae is most closely related to F. kenyoshiensis (Chinzei) from the middle Pliocene of Japan. 

The left valve of F. kenyoshiensis is very similar, both 

in gross features and in the texture of its interstitial 

riblets (see Chinzei, 1960, p. 66, fig. 2). The right 

valve of F. kenyoshiensis has narrower and more prominent ribs and may be more inflated, and these characteristics make it intermediate between F. hallae and 

F. takahashii.

The inclusion of F. liallae in the fauna of the socalled Submarine Beach at Nome and in a similar fauna 

at Kivalina, north of Kotzbue Sound, is open to some 

question. Until the summer of 1961, when an old mine 

dump near the Solomon River was rediscovered, the 

exact locality of F. hallae was not known. Unfortunately, only a few unidentifiable scraps of other mollusks were found to occur with it, although F. hallae 

itself seems to have been fairly abundant. Not even 

fragments of F. hallae have been found in the Submarine Beach at Nome. The possibility certainly exists 

that the beds on Solomon Eiver are a pre-Submarine 

Beach deposit not represented at Nome. A nearly complete but highly polished left valve of F. hallae from 

Kivalina, now in the California Academy of Sciences, 

and fragments of the species in Geological Survey collections apparently came from fossiliferous beds now 

exposed, but they have a preservation different from

that of the rest of the fauna, and they could have been 

reworked into the beds now containing them from a 

submarine deposit. Until this species can be shown 

with certainty to have lived in the Submarine Beach, 

I am inclined to regard its inclusion in the fauna of the 

Submarine Beach as tentative.

Types: The lectotype (USNM 499059), a right valve labeled 

the type of P. liallae, has a height of 120 mm and a length of 

126 mm. A left valve (USNM 499061) labeled P. rhytidus is 

the best preserved known specimen.

Type locality: Immediately above bedrock and about 20 ft 

below sea level in a prospect mine shaft, 0.8 mile east of Solomon 

townsite, and about 1 mile inland on the delta of the 'Solomon 

River, USGS 9250, M1267.

Other occurrences: Small valley on north side of Kivalina 

River about 1.3 miles above its mouth on Kivalina Lagoon and 

about 5.3 miles north-northwest of Kivalina Village, Alaska, 

USGS M1817.

Genus MIYAGIPECTEN Masuda, 1952

Miyaffipecteti Masuda, 1952, Trans. Proc. Paleont !Soc. Japan, 

new ser., no. 8, p. 251.

Type species (by original designation) : Miyagipecten inatsiimoriensis Masuda. Nanakita Formation 

(middle Miocene). Miyagi Prefecture, Japan.

Discussion. Miyagipecten has a smooth Amusiumlike right valve. The left valve has numerous fine radial 

ribs that do not extend to the margin in adult specimens. 

The Alaskan species, here described, has a smooth right 

valve and fine ribs on its left valve. In addition, its 

left valve has a strong metal lathelike microsculpture. 

I am assigning the Alaskan species to Miyagipecten 

because of its ribless right valve.

Although its ribs are more numerous, the fine ribs 

and microsculpture of the Alaskan species are similar 

to the ribbing and microsculpture of the left valve of 

two Japanese Pliocene species, Pecten plebejus Yokoyama (see Akiyama, 1962, pi. 1, fig. 5), and Pecten 

tokunagai Yokoyama (see Masuda, 1962b, pi. 24, fig. 

9b). Akiyama (1962, p. 109) recognized both species 

and included them in Patinopecten (Masudapecten), 

but Masuda (1963, p. 149) combined them under 

P. tokunagai, which he made the type of a new genus, 

Yabepecten. Both species have moderately small or 

weak radial ribs on the right valve. The ribs of P. 

pleltejus, however, are very weak, and the upper part of 

the disc is nearly smooth.

Inasmuch as Masuda (1962b, p. 210) thought 

P. plebejus and P. tokunagai were one species, and the 

species so construed has ribs on its right valve that 

range from moderately strong to nearly obsolete, it 

would be possible for a related species to have a smooth 

right valve. The smooth right valve of Miyagipecten 

led Masuda (1957, p. 31) to assign it to the subfamily 

Amusiinae. In my opinion, this assignment is debata-
LOCALITIES 45

ble. I am inclined to believe that Miyagipecten 

alaskensis, here described, is much more closely related 

to Yabepecten and to some species of Masudapecten 

than it is to Amusium.

Miyagipecten alaskensis MacNeil, n. sp. 

Plate 6, figures 4, 5

Description. Shell of medium size and suborbicular, 

medium to weakly inflated. Right valve Amusium-like 

sculpture well developed with two apparent resting 

stages shown on the holotype. Anterior ear of right 

valve moderately broad and of moderate length, no 

well-defined byssal area; byssal notch shallow. Posterior ear of right valve moderately short with a steeply 

sloping posterior margin. Left valve with numerous 

small, rounded radial ribs, increasing in number by the 

addition of intercalary ribs ventrally, the intercalary 

ribs rapidly becoming as strong as the primary ribs. 

Microsculpture reticulate or metal lathelike, covering 

the interspaces and ribs alike. Ears of left valve 

unknown.

Discussion. This species is known from the external 

and internal mold of several right valves and one incomplete external mold of a left valve. It occurs in 

a hard gravelly sandstone in association with a large 

unidentified fragment of Patinopecten (Lituyapeclen). 

It is not absolutely certain that the two incomplete 

valves here figured belong to the same species. The 

ventral half of the internal mold of a specimen with 

attached valves show that neither valve has internal 

ribs; the internal mold comes from the external mold 

of a right valve. The probability is, therefore, that 

this is not an Amusium, but the possibility exists that 

the fragment of a ribbed left valve is a Ohlatnys.

No pectinid like this has been reported previously 

from America. It is presumed to be related to Miyagipecten, although I cannot find a description of a 

species of that genus that refers to a microsculpture 

like that of M. alaskensis. M. alaskensis may be closely 

related to M. saromensis Hasimoto and Kanno (1958, 

p. 287, pi. 42, figs. 1-5) from the Chirai Formation 

(middle Miocene) of Kitami Prefecture, nothern Hokkaido. The right valve of M. saramensis has faint 

radial ribs, unlike the present species, but the radial 

ribs of the left valve are of similar texture.

Types: The holotype (USNM 645049), an incomplete right 

valve, has an estimated height of about 55 mm, although 

another incomplete right valve probably was closer to 85 mm. 

The paratype is numbered USNM 645050.

Type locality: Nunatuk north of the east end of the Pinnacle 

Hills, lat 60°09'40" N., long 140°16'40" W., Malaspina district, 

Alaska, USGS M1321. The horizon is probably early Pliocene.

223-848 O 67 5

LOCALITIES

U.S. National Museum catalog numbers (Recent mollusks 

accessioned by the Division of Mollusks, U.S. National 

Museum, are cataloged by species lot; no separate locality 

number is given. New catalog numbers are not assigned to 

specimens subsequently made types or to figured specimens):

110462. Albatross sta. 5021, Okhotsk Sea, 73 fathoms. Recent.

150220. Alaska Peninsula, Alaska. Recent.

California Academy of Sciences localities (the California Academy of Sciences maintains both a locality register and a specimen catalog for types and figured specimens): 

18493. St. Paul Island, Pribiloff Islands, Alaska. Recent.

G. D. Hanna, collector. 

31879. Puget Sound, Wash. Recent. 

34333. Two miles off Arcon Camp, Point Barrow, Alaska,

71°21'10" N., 156°46'45" W., 140ft. G. D. Hanna,

collector. 

34337. Three and one-half miles off Wainwright, Arctic coast of

Alaska, 70°40'45" N., 160°06'40" W., 63 ft. G. D.

Hanna, collector. 

34347. Seventeen miles magnetic west of Arcon Beach, Arctic

coast of Alaska. 7l°21'30" N., 157°23'00" W., ?300

ft. G. D. Hanna, collector. 

34358. Five miles off Point March, Arctic coast of Alaska.

70°38'30" N., 160°19'00" W., 69 ft. G. D. Hanna,

collector.

University of California (Berkeley) locality (the University of

California at Berkeley maintains both a locality register and

a catalog of types and figured specimens):

A906. North wall of Wild Horse Canyon, 1,000 ft south of the

E. cor. sec. 8, T. 20 S., R. 9 E., 100 ft below base of

barren gravels of Paso Robles Formation. King City

quad., Monterey County, Calif. J. Kirby, collector.

University of California (Los Angeles) locality:

4674. Skonun Point, 5 miles east of Masset on the north coast 

of Graham Island, Queen Charlotte Islands, Canada. 

Skonun Formation (probably late Miocene). Richfield Oil Co., collector.

U.S. Geological Survey Cenozoic localities (Washington register)

(the U.S. Geological Survey maintains a locality register for

Cenozoic mossusks at Washington and for Cenozoic mollusks at

Menlo Park, Calif. Collections and records once at Denver

are now at Menlo Park. Types and figured specimens are

given U.S. National Museum catalog numbers and deposited

in the U.S. National Museum, Washington):

3373. East side of Chichagof Bay, Alaska Peninsula, Alaska.

Acila shumardi zone, Stepovak Series of Palache

(1904) (Oligocene). Harriman Expedition, 1899,

G. Palache, collector.

3363. Near northwest corner of Popof Island, Shumagin 

Islands, Alaska. Acila shumardi zone, upper part 

(Oligocene). W. H. Dall, collector.

4321. Burls Creek, 3.58 miles, 152.5° E. of N. from mouth of 

Split Creek on Bering Lake, Katalla district, Alaska. 

Burls Creek Shale Member (late? Oligocene) of 

Katalla Formation. A. G. Maddren, collector. 

4323. Split Creek, 1.98 miles, 152.5° W. of N. from mouth of 

Split Creek on Bering Lake, Katalla district, Alaska. 

Tokun Formation, upper part (Oligocene). A. G. 

Maddren, collector.
46

4537. "Gravels under tundra near Nome, Alaska, at a depth 

of 50 ft" (?near Center Creek, about 2 miles from 

shore of Bering Sea). Intermediate Beach (middle 

Pleistocene). F. H. Moffit, collector.

4538. Otter Creek, about 2 miles from shore of Bering Sea. 

Shells said to come from 54 ft below surface and 20 ft 

above sea level, near Nome, Alaska. Probably 

Intermediate Beach (middle Pleistocene). Given to 

F. L. Hess by J. J. Beaver, collector.

5037. East side of Unga Island about one-fourth mile from 

northeast corner, 70 ft above mean tide level. Shumagin Islands, Alaska. Acila shumardi zone, upper 

part (Oligocene). W. W. Atwood, collector.

5046. North side of Port Moller, about due east from Hot 

Springs, Alaska Peninsula, Alaska. Mytilus middendorffi, zone, Unga Conglomerate (middle Miocene). 

W. W. Atwood, collector.

5074. Mine dumps on Center Creek near Nome, Alaska. 

Gravels worked in these mines lie 18-21 ft above sea 

level. Intermediate Beach (middle Pleistocene). 

E. M. Kindle, collector.

5256. Postglacial deposits on Douglas Island, near Juneau, 

Alaska. A. Spencer, collector.

5313. Mine on Center Creek iy2 miles from coast and 32 ft 

below surface, Nome area, Alaska. Intermediate 

Beach (middle Pleistocene). Alaska Yukon Exposition, 1909, collectors.

5461. Mouth of Eagle River on Lynn Canal, north of Juneau. 

Postglacial deposits. A. Knopf, collector.

6694. Mouth of large gulch on south slope of White River 

valley at foot of glacier [1913], 2.40 miles 14° E. of 

N. from mouth of Fulton Creek, Bering Glacier A-4 

quad., Yakataga district, Alaska. About 1,500 ft 

above base of Yakataga Formation (horizon probably 

middle Miocene). A. G. Maddren, collector.

7477. Dump of mine shaft 80 ft deep, 1 mile from coast 

between Dry and Bourbon Creeks, Nome area, Alaska. 

Probably Intermediate Beach (middle Pleistocene). 

F. L. Hess, collector.

7619. (= 5074?) Mine dumps half a mile west of Nome, Alaska. 

Submarine Beach (late Pliocene or early Pleistocene). 

E. M. Kindle, collector.

9250. Prospect mine shaft about 1 mile inland and about 0.8 

mile east of Solomon townsite on the delta of the 

Solomon River, immediately above bedrock and about 

20 ft below sea level. Submarine Beach or possibly 

beds older than the Submarine Beach at Nome (late 

Pliocene or early Pleistocene). Otto Halla, collector.

12066. Glacier Highway along north side of Auke Bay, about 

about midway between Point Louisa and Auke Lake, 

Juneau area, Alaska. Postglacial deposits. M. L. 

Merritt, collector.

14866. Dumps of a line of old drift mines trending 60° W. of 

N., between Center and Bourbon Creeks about 2 

miles north of the mouth of Snake River, Nome 

area, Alaska. Intermediate Beach (middle Pleis' 

tocene). J. B. Mertie, Jr., collector.

15437. Unnamed creek on the north flank of and parallel to 

Yakataga Ridge, 0.3 mile 16° E. of N. from peak 

2430 near west end of Yakataga Ridge. Bering 

Glacier A-4 quad., Yakataga district, Alaska. Probably in basal part of Yakataga Formation (horizon 

lower middle Miocene). E. M. Spieker, collector.

CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

16898. North end of spur projecting north into Bering Glacier, 

12.8 miles, 58° E. of N. from north end of Hanna 

Lake. Bering Glacier A-4 quad., Yakataga district, 

Alaska. Near middle of Poul Creek Formation 

(horizon probably upper Oligocene or lower Miocene). 

D. J. Miller, collector.

16907. One and one-half miles, 14° west of northeast corner 

"clam lagoon," on sea cliff 280 ft above sea level. 

Adak Island, Aleutian Islands, Alaska. Early Pleistocene. R. R. Coats, collector.

16908. Floor of quarry at garbage dump, 3 miles west of East 

Cape at elevation 125 ft. Amchitka Island, Aleutian Islands, Alaska. Early or middle Pleistocene. 

R. R. Coats, collector.

16908a. Same as USGS 16908.

17743. West side of Middleton Island, Alaska, approximately 

3.34 miles, 153° W. of N. from northern tip of island, 

270-870 ft below top of exposed section in massive 

medium-gray to greenish- and olive-gray conglomeratic 

sandy mudstone; contains rock fragments as much 

as 4 ft in diameter. Probably early Pleistocene. 

D. J. Miller, collector.

17744. Bay near center of west side of Middleton Island, 

Alaska, approximately 2.34 miles, 160° W. of N. 

from northern tip of island, 870-980 ft below top of 

exposed section in conglomeratic sandy mudstone 

containing thin interbeds of conglomerate, coarse 

sandstone, and coquina. Probably early Pleistocene. 

D. J. Miller, collector.

17745. Northeast side of Middleton Island, Alaska, approximately 0.68 miles, 147° E. of N. from northern tip 

of island, 980-1,490 ft below top of exposed section 

in conglomeratic sandy mudstone; rock fragments in 

gravel are mainly of pebble and cobble size. 

Probably earlyPleistocene. D. J. Miller, collector.

17746. South tip of Middleton Island, Alaska, 1,490-1,535 ft 

below top of exposed section in conglomeratic sandy 

mudstone; contains rock fragments as much as 3 ft 

in largest dimension and thin beds of coquina at top 

and base of unit. Probably uppermost Pliocene. 

D. J. Miller, collector.

17817. South flank of Chaix Hills near margin of Malaspina 

Glacier [1947], 3.68 miles, 45° W. of S. from north 

end of Crater Lake, Bering Glacier quad., Malaspina 

district, Alaska. Yakataga Formation (horizon probably upper Miocene). D. J. Miller, collector. 

U.S. Geological Survey Cenozoic localities (Denver register;

transferred to Menlo Park):

D3 (T). High west-facing side of Kanaga Island, north of 

coastal lakes and about 4J/2 miles south-southwest 

of Kanaga Volcano, Kanaga Island, Aleutian 

Islands, Alaska. Horizon early or middle Pleistocene. G. L. Snyder, collector.

D26 (T). Lens of tuffaceous coquina conglomerate 5-20 ft 

thick and overlying an andesite flow, 51°41'25" N., 

177°50'30" W., southeastern Tanaga Island, 

Aleutian Islands, Alaska. Early Miocene(?) 

G. L. Snyder, collector.

D46 (T). Loose sandy beach deposit about 135 ft above sea 

level at the head of South Bight, south side of 

Amchitka Island, Aleutian Islands, Alaska. 

51°22'50" N., 179°28'58" E. Horizon early or 

middle Pleistocene. H. A. Powers, collector.
LOCALITIES 47

D47 (T). Isocrinus-bearmg beds, 51°24'32" N., 179°09'44" E., 

Amchitka Island, Aleutian Islands, Alaska. Banjo 

Point Formation (Oligocene?). H. A. Powers, 

collector.

D50 (T). 210-258 ft below top of measured section on Carter 

Creek a stream flowing into Camden Bay, NE% 

NW% quad. 681, Arctic coast, northeastern Alaska. 

Overlain by the type Nuwok Formation of Dall 

(1919) and underlain by nearly 7,000 ft of nonfossiliferous beds. Horizon probably middle or 

upper Miocene. R. H. Morris, collector.

D53 (T). Tidal flat in Usof Bay, Unalaska Island, Aleutian 

Islands, Alaska. Recent, E. H. Meitzner and 

R. P. Platt, collectors.

D184 (T). Ocean beach reef, 1.03 miles, 57° E. of S. from 

mouth of Dagelet River, Mount Fairweather 

quad., Lituya district, Alaska. Upper part of 

Yakataga Formation (horizon probably Pliocene). 

D. J. Miller, collector.

D187 (T). Ocean beach reef, Icy Point measured section, 1.04 

miles, 22° W. of S. from mouth of Kaknau Creek 

(Palma Bay, Mount Fairweather quad.), Lituya 

district, Alaska. Upper part of Yakataga Formation (horizon probably upper Miocene or lower 

Pliocene). J. F. Seitz, collector.

D222 (T). Steelhead Creek, probably from reefs at mouth 

of creek, about 4.5 miles southeast of entrance to 

Lituya Bay. Mount Fairweather C-5 quad., 

Lituya district, Alaska. Upper part of Yakataga 

Formation (horizon probably Pliocene). C. E. 

Kirschner and J. E. Heppert, collectors.

D263 (T). South side of Point Glorious, about 0.1 mile east of 

the westernmost part of the point, Mount St. 

Elias quad., Malaspina district, Alaska. Upper 

part of the Yakataga Formation (horizon probably 

Pliocene). G. Plafker, D. J. Miller, and D. L. 

Rossman, collectors.

D306 (T). Coleville River at Ocean Point, about 8 miles below 

mouth of Kikiakrorak River, northern Alaska. 

Lower part of Gubik Formation (horizon probably 

lower or middle Pleistocene). R. Stefanson, 

collector.

D318 (T). Beach at Wainwright, Arctic coast of Alaska. 

Recent. U.S. Coast Guard, collectors.

D373 (T). Beach at Cape Kialegah, St. Lawrence Island, 

Alaska. Recent. E. H. Muller, collector.

D386 (T). Raised beach at Narssurssuk, Greenland, terrace 

lies 10-35 ft above sea level. Probably postglacial. W. E. Davies, collector.

U.S. Geological Survey Cenozoic localities (Menlo Park register): 

M212. End of highway north of Douglas Island bridge, Douglas 

Island, Juneau area, Alaska. Postglacial deposits. 

D. J. Miller, collector.

M213. Beach at end of Douglas Island north of bridge, near

Juneau, Alaska. Recent. D. J. Miller, collector. 

M214. South side of Fish Creek on road north of bridge.

Douglas Island, Juneau area, Alaska. Postglacial

deposits. D. J. Miller, collector. 

M216. Cut on Glacier Highway at Lena Cove, Juneau area,

Alaska. Postglacial deposits. D. J. Miller, collector. 

M217. Cut on Glacier Highway at Point Louisa, Juneau area,

Alaska. Postglacial deposits. D. J. Miller, collector.

M218. Cut on Glacier Highway along north shore of Auke 

Bay, north to northwest of Indian Point. Postglacial 

deposits. D. J. Miller and W. H. Condon, collectors. 

M223. East arm of Excursion Inlet, north side of Icy Strait 

between Lynn Canal and Glacier Bay. Dredged from 

depth of 150 ft. D. J. Miller, collector.

M234. East arm of Excursion Inlet on small bay 1.5 miles 

north of point between two arms. Dredged 500 ft 

offshore at depth of 50 ft. D. J. Miller, collector. 

M243. Cuts on both sides of road 0.8 mile northeast of Fish 

Creek bridge, Douglas Island, Juneau area, Alaska. 

Postglacial deposits. D. J. Miller, collector. 

M333. Tailing piles about \% to 2 miles north of Nome, 

Alaska. Intermediate Beach (middle Pleistocene). 

D. M. Hopkins, collector.

M337. Rat Island, Aleutian Islands, Alaska. 51°48'58" N., 

178°19'02" E. Gunners Cove Formation (Oligocene?). H. A. Powers, collector.

M1025. Flats of east tributary to Mud Bay along east upstream 

fork, about 3.7 miles a little east of south from Jerk 

Triangulation Station, Port Moller quad., Alaska 

Peninsula, Alaska. Probably in upper part of Acilo, 

shumardi zone (Oligocene). M. C. Lachenbruch, 

collector.

M1084. Tailing piles about 1.6 miles north of north edge of 

Nome, Alaska. Intermediate Beach (middle Pleistocene). D. M. Hopkins, collector.

Ml 144. Topsy Creek, Lituya district, Alaska, approximately 

58°36'15" N., 137°27'45" W. Upper part of Yakataga Formation (horizon upper Miocene or lower 

Pliocene). British Petroleum Exploration Co., 

collectors.

Ml 154. Icy Point, Lituya district, Alaska, approximately 

58°22'45" N., 137°05'00" W. Upper part of Yakataga Formation (horizon upper Miocene or lower 

Pliocene). British Petroleum Exploration Co., 

collectors.

M1252. Tailings of prospect shafts on northeast slope to Otter 

Creek below Florence Gulch, east of Nome, Alaska, 

about 64°29'30" N., 165°17'10" W. Intermediate 

Beach (middle Pleistocene). D. M. Hopkins, 

collector.

M1256. Dredge tailings near oil tanks in F. A. A. warehouse 

on west side of Snake.River, Nome, Alaska, 63° 

30'00" N., 165°25'30" W. Submarine Beach (late 

Pliocene or early Pleistocene). D. M. Hopkins, 

collector.

M1267. Tailings of prospect shaft of Otto Halla. On delta 

of Solomon River a mile inland and 0.8 mile east 

of Solomon townsite, 64°33'45" N., 164°24'40" W., 

about 25 miles east of Nome, Alaska. D. M. Hopkins, collector. Same locality as USGS 9250.

M1321. Nunatuk north of the east end of the Pinnacle Hills, 

east of the Seward Glacier, 60°09'40" N., 140°16'40" 

W., Malaspina district, Alaska. Upper part of 

Yakataga Formation (horizon probably lower Pliocene). British Petroleum Exploration Co., collectors.

M1339. Beach near Point Hope, Alaska, 68°25'00" N., 166° 

24'00" W. Recent. G. W. Moore, collector.

M1494. About 320 ft below top of glacial-marine sequence 

estimated to be about 3,520 ft thick, Tugidak Island, 

Trinity Islands, Alaska, 56°31' N., 154°42' W. 

Probably late Pliocene. G. W. Moore, collector.

M1621. St. Paul Island, Pribiloff Islands, Alaska. Recent.

M1622. Same as M1621.
48 CENOZOIC PECTINIDS OF ALASKA, ICELAND, AND OTHER NORTHERN REGIONS

M1741. Cliff near southwestern end of Middleton Island, 

Alaska; close to the top of Miller's (1953, p. 23) 

measured section, and about 550 ft below the top 

of the exposed section as determined by Plafker. 

Horizon probably lower Pleistocene. G. Plafker, 

collector.

M1742. Cliff on west side of Middleton Island, Alaska; about 

1,080 ft below top of exposed section as determined 

by Plafker. Horizon probably lower Pleistocene. 

G. Plafker, collector.

M1743. Cliff on west side of Middleton Island, Alaska; about 

1,200 ft below top of exposed section as determined 

by Plafker. Horizon probably lower Pleistocene. 

G. Plafker, collector.

M1744. Cliff on west side of Middleton Island, Alaska; about 

1,250 ft below top of exposed section as determined 

by Plafker. Horizon probably lower Pleistocene. 

G. Plafker, collector.

M1746. Cliff at south end of Middleton Island, Alaska; about 

1,800 ft below top of exposed section as determined 

by Plafker. Horizon probably uppermost Pliocene. 

G. Plafker, collector.

M1751. Extreme southeast tip of Middleton Island, Alaska; 

about 3,550 ft below top of exposed section as determined by Plafker. Horizon probably upper 

Pliocene. G. Plafker, collector.

M1752. Extreme southeast tip of Middleton Island, Alaska; 

about 3,650 ft below top of section as determined by 

Plafker. Horizon probably upper Pliocene. G. 

Plafker, collector.

M1753. Extreme southeast tip of Middleton Island, Alaska; 

about 3,700 ft below top of section as determined by 

Plafker. Horizon probably upper Pliocene. G. 

Plafker, collector.

M1754. Extreme southeast tip of Middleton Island, Alaska; 

about 50 ft above base of section determined by 

Plafker to be about 3,900 ft thick. Horizon probably 

upper Pliocene. G. Plafker, collector.

M1817. North bank of Kivalina River, about 67°49'00" N., 

164°37'12" W., between Kotzebue Sound and Point 

Hope, Alaska. Late Pliocene or early Pleistocene. 

D. S. McCulloch, collector.

M1828. First high bluff on southwest side of Kuk River at its 

mouth, 70°44'51" N., 160°07'54" W., Arctic coast of 

Alaska near Wainwright. Gubik Formation (horizon probably middle Pleistocene). D. S. McCulloch, 

collector.

M1842. Approximately 2,700 ft above base of measured section 

at Icy Point, Mount Fairweather quad., Lituya district, Alaska. Upper part of Yakataga Formation 

(horizon probably upper Miocene or lower Pliocene). 

G. Plafker, collector.

M1851. Approximately 4,750 ft above base of measured section 

along east side of Deadfall Creek, west of La Perouse 

Glacier, Mount Fairweather quad., Lituya district, 

Alaska. Measured section extends 58°29'54" N., 

58°30'18" N. to 58°30'18" N., 137°20'54" W. 

Upper part of Yakataga Formation (horizon probably 

Pliocene). G. Plafker, collector.

Ml869. Reef west of Deadfall Creek, west side of La Perouse 

Glacier, Mount Fairweather quad., Lituya district, 

Alaska. Upper part of Yakataga Formation (horizon 

probably Pliocene). G. Plafker, collector.

M1875. Near top of measured section in Chaix Hills, Bering 

Glacier quad., Malaspina district, Alaska. Uppermost part of Yakataga Formation (horizon probably 

upper Pliocene). G. Plafker, collector.

M1878. In lower part of measured section in Chaix Hills, Bering 

Glacier quad., Malaspina district, Alaska, approximately 6,000 ft lower stratigraphically than M1875. 

Yakataga Formation (horizon probably about basal 

Pliocene). G. Plafker, collector.

M1895. About 1,900 ft above the base of a glacial-marine section 

estimated to be about 3,520 ft thick, west side of 

Tugidak Island, Trinity Islands, Alaska, 56°27'25" 

N., 154°46'10" W. Probably Pliocene. G. W. 

Moore, collector.

M2054. Upper part of section on Middleton Island. G. Plafker, 

collector. Probably from M1742.

M2055. Raised beach deposit at Reykjavik Airport, 13 meters 

above sea level; radiocarbon dated at 10,200 yrs B.P. 

Iceland. T. Einarsson, Univ. Research Inst., Reykjavik, Iceland, collector.

M2056. Beach about 1 mile north of Wainwright, Alaska. 

Recent. O. W. Geist and P. Sellman, collectors.

M2062. Beach at Wainwright, Alaska. Recent. D. S. McCulloch, collector.

M2064. Beach of Sitkalidak Island, off southeast coast of 

Kodiak Island, Alaska. Recent. E. J. Moore, 

collector.

M2130. Quarry now filled by housing subdivision, about 1% 

miles south of the northeast end of runway of Orange 

County Airport and near the head of Newport Bay, 

Tustin quad., Orange County, Calif. Fernando 

Formation (horizon upper Pliocene). J. G. Vedder, 

collector.

M2131. East coast of Point Divide, approximately 3 miles 

southeast of Point Divide, between Herendeen Bay 

and Port Moller, Alaska Peninsula. Late Miocene(?). 

Shell Oil Company, collectors.

M2132. West coast of Cape Aliaksin, approximately 2 miles 

northeast of Point Aliaksin, south side of Alaska 

Peninsula, Port Moller, quad., Alaska. Unga Conglomerate (middle Miocene). Shell Oil Company, 

collectors.

M2133. West side of spit, Punak Islands, St. Lawrence Island, 

Alaska. Recent. H. B. Alien, collector.

M2153. Beach exposure southwest of lighthouse Valadalstorfa, 

Breidhavik, Tjornes district, northern Iceland. Base 

of bed 14 at Stapavik, the uppermost fossiliferous 

bed of the Breidhavik section (early glacial leistocene). D. M. Hopkins, collector.

M2155. Bed 21 of Tjornes section, 100 miles south of Baejarlaekur, Husavik quad., Tjornes district, northern 

Iceland (Cardium zone, early Pleistocene). D. M. 

Hopkins, collector.

M2164. Bed 20 of Tjornes section at Kambgja, Husavik quad., 

Tjornes district, northern Iceland (Cardium zone, 

early Pleistocene). Carlie Bjarnisson, collector.

M2203. Bed 10 of Tjornes section, Svarthamar and Stori 

Svarthamar south of Hallbjarnastadhad, Husavik 

quad., Tjornes district, northern Iceland (Madra 

zone, late Pliocene). D. M. Hopkins, collector.

M2464. Recent, beach at Tjornes, Iceland. D. M. Hopkins, 

collector.
REFERENCES 49

M2519. Dredged from the Westerschelde, westernmost Netherlands. Probably from beds of Scaldesian (early 

Pleistocene) age. Obtained from C. O. van Regteren 

Altena, Rijksmuseum van Natuurlijke Historic, 

Leiden.

REFERENCES

Abbott, R. T., 1954, American seashells: New York, D. Van Nostrand Co., 541 p., 32 pis., 100 figs.

Addicott, W. O., 1965, Some western American Cenozoic gastropods of the genus Nassarius: U.S. Geol. Survey Prof. Paper 

503-B, 21 p.

Akiyama, Masahiko, 1962, Studies on the phylogeny of Patinopecten in Japan: Tokyo Kyoiku Daigaku Sci. Repts., Sec. C, 

v. 8, no. 74, p. 63-122, pis. 1-8.

Altena, C. O. van Regteren, 1937, Bydrage tot de kennis der fossiele, subfossiele en recente mollusken, die op het nederlandsche strand aanspoelen, en hunner verspreiding: Rotterdam, 

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INDEX

[Italic page numbers indicate descriptions]

A Page 

Acila empirensis.----------------------------- 43

shumardi.- ----- ---- - ---.--------.- 39,40

Acmaea........-....-... ______________________ 37

(Aequipecten) hallae, Pecten.------------------ 44

Alaskan Pectinidae___---__--_--____-______ 2

alaskense, Pecten (Propeamusium)..--- _______ 6

Polynemamussium... ........_______ 6, 7, pi. 6

Propeamussium (Parvamussium).. _______ 6

alaskensis, Miyagipecten..------------.....,.45, pi. 6

Pec.«n_ _ _--_____-___..._____ 6,7

(Propeamuslum) _____-__________.. 6

(Pseudoamussium)------------------- 6

albicans, Pecten----- ___.____..__.....___ 10

albida, Chlamys islandica... ___.____ 27,30,34,35,36

Chlamys (Chlamys) islandica.------------- 36

albidus, Pecten... _______________________ 35

Pecten hericius------... ___________________ 36

(Chlamys) hastatus_______________ 36

hericius----------------------------- 36

(Pecten) ftas.a-tts---__________________- 36

aletes, Pecten---. ... ________________________ 10

alexandri, Pecten (Chlamys)----... ____________ 9

alternicostata, Chlamystauroperstriata- ________ 9

altiplicatus, Pecten.-.... ____________________ 15

amchitkana, Chlamys hanaishiensis,----- 23,29,30,32

Chlamys (Chlamys) hanaishiensis___... SO

pis. 12,13,14,15,22

Amusmm.-----------------------...______ 37,44,45

squamigerum.---------------------------- 6

Amussiopecten _____________________________ 43

<7Kjras pZana__________________________ 43

Anadyr Gulf..._--_-_-_____-_-_______________ 3

anapleus, Chlamys-.-. ____________________ 22,27

andersoni, Pseudamusium. ______________ 8

arakawai, Chlamys-.-------------------------- 9

ara.a, GMaTO_/s-----------_--_--------_---_--__ 18

aratus, Pecten.. _----______-__,_________- 18

^4raz ...erna7M-__---_.________________________ 40

arconis, Chlamys pseudislandica.-.... _________ 31

Chlamys (Chlamys) pseudislandica.-.- _ 3S, pi. 23 

Arctic currents. _----------------___-__--___-- 3

Arctinula.------- __________________________ 7

groenlanAica,.---- ------------------- 7, 8, pi. 4

(Arctinula) groenlandicum, Palliolum.. _______ 8

Propeamusium (Palliolum).---------- __ 7

arenaria, Mya. _____________________________ 18

ashiyaensis, Pecten (Chlamys)---------------.- 37

Asiatic faunas..-_-------------_-________ 3

asperrimus, Pecten____________..._____ 9

assiniboiensis, Pecten..------------------------ 38

atwoodi, Epitonium.-------------------------- 40

Aviculopectinidae. __--_-_____--______--__--_ 2

B 

Balanus &afattttS-_--_---__--___-__-------_--_- 33

balanus, Lepas------ _____________.... 33

Bathyarca 0Zac.a?.*_.______-_______ .__-_--__ 3^

Beaufort Sea.-..------.- __-___.________--_ 4

behringiana, Chlamys islandica.--... __________ 24,26

Pecten islandicus________________________ 24

behringianus, Pecten islandicus---------------- 1,2

benedictus, Pecten---- _______________________ 10

Bering Sea...-___-_-_______-__--___-__-____-_ 2

Bering Sea currentS-___.-_.__ _______ _________ 3

Bering Strait------------------- ------------- 3

beringiana, Chlamys__-_.___._----_.______

14,15,18,21,24,25,26,27, 

Chlamys (Chlamys)--..-... $4, pis. 20, 21, 

colvillensis, Chlamys (Chlamys)---- __ 26,

graui, Chlamys ......-_____.--.._ 25,

Chlamys (Chlamys) ___----__-_-.____

strategus, Chlamys....... ___________ 18,25,

Chlamys (Chlamys)-------------------

unalaskae, Chlamys______-___-__.-__

Chlamys (Chlamys)... __-___-_-- SI, 

beringianus, Chlamys....-- __---_________

Pecten (Chlamys)...-_.___.__--_--.-.--- 

( Chlamys) islandicus- _______________

(Pecten).-----------------------------

binominatus, Pseudamusium.-----------------

borinquense, Pecten...------------------------

bowersi, Vertipecten---------------------------

branneri, Pecten--- ... ____________________..._

breidavikensis, Chlamys___.____.__.____ 16,

Chlamys ("Chlamys").--------- - -16,

byoritzuensis, Pecten (Vola).... ...__________

C

Page

11, 

28,32 

23,24 

pi. 18 

26,32

25

pi. 20 

24,25

17

26

27 

8

10

40

38,39 

25,34 

pi. 25

10

calamitus, Polynemamussium. __________ 7

-- ... ___.. 7 

Camptonectes.-- ________ . __ -__-_ _ 7,11,20,30,39

Cape Kruzenstem. __________________________ 3

Cardium......--.- ... ... ____________________ 34

caurinus, Patinopecten...-- _ __ _ ___________ 41

Patinopecten (Patinopecten)-. ...--..-.... 41, pi. 4

Pecten....... .............................. 40,42

Cenotaph Island.... ___________ _ _ _ _____ 2

chaixensis, Chlamys. .... _ __ _ 17,18,19,21,26,28,30

Chlamys ("Chlamys")-- _ ___________ /9,pls. 9,10

chinkopensis, Chlamys.-....- _ ._ _ ______ 28,29,34

Chlamys (Chlamys) picoensis-.. .. .. 28, pi. 11

pkoensis. ......... _ _ __ _ 29,30,33,34,35

Chlamys......... ___ ... ________ 2,

8, 9, 11, 13, 14, 20, 23, 24, 29, 33, 37, 38, 40, 45 

anapleus... ._..-_-_-________,__-_._____-- 22,27

arakawai. .--____-_-_________._-_._._____- 9

arata....- __ _. _ .._ __ .... _ . _ ...-- 18

beringiana. .... 11, 14, 15, 18, 21, 24, 25, 26, 27, 28,32

graui....----------- ---------- 25,26,32

strategus __ ._-__________._ __ 18,25,26,27

unalaskae. ___________________________ 25

beringianus...-...-...-- _ ________ _ ... 24,25

breidavikensis...------------..--------- 16,25,34

chaixensis .--- - 17,18,19,21,26,28,30 

chinkopensis-. _________._-____-_-.--___ 28,29,34

coatsi..... ................. 17,18,26,30,31

middletonensis.-. ... ___ 17,18,19,26,31,32

cosibensis. ..11, 17, 18, 20, 21, 24, 25, 26, 28, 29, 34, 35 

cosibensis- ____--_._______-----__ _ ... 17

hanzawae __ __________________ 17,18,20,25

heteroglypta,. ----------- ______ __ 17,19

cos.eZ,a.a_--_ ----------------------------- 33

daishakensis. -_________________-____-__--- 9

decemnaria ...... ____-___-_____-_---____-__ 18

elongatus ------------------------ __-__ 9

erythrocomata. ------------------------ 29,30,32

 - 17,25

grunskyi.--------------------------------- 38

Page

Chlamys Continued

hanaishiensis------- 23,24,26,28,29,30,32,34,35

amchitkana.-... _________ 23,29,30,32 

harmeri_________-----_____ 10,15,34

hastata........................... 14,15,21,24,37

hericia................................ 14

hericius...- _____-_-.____ 14,15,21,24

pugetensis...- _.----_-.- ........ 15

hericius- . _ ._.__ 21,24 

hindsii_________-_--________ 22,26 

imanishii...-.-___.... _____ 33

islandica..-.. -.............. 1,3,14,16,17,21,

22,23,25,28,29,30,31,32,33,34,35,36 

albida........................ 27,30,34,35,36

behringiana..-.......- __-_-.__-.__ 24,26

erythrocomata.......... 28,29,30,33,34,35,36

hindsii_______________..._ 25 

insculpta ...__._ _ ..___ 33 

islandica.-. __._--_----_..--_..._ 35

kanagae... ................ 28,29,34,35,36

kinoshitai.... ______.--- ..___-_--. 29

osugii ----------. ____________.. 29

powersi --.. -.-.. 27,31,34,35,36 

thulensis................-.--..-....... 35

islandicusjordani.------------------------ 22,23

iwakiana______.___.--_--_-_-_-. 9

jordani___________________.. __ 22

justiana__________-.____..___. 9,10

kincaidi.. ........................... 22,23,30

kinoshitai.- 28,32

kitamurai..- -__----____----__-___-_-.-- 11

lioica....-- 19,20,21

longolaevis..-------------- _-_.-_.-_-. 17

matchgarensis.--- _____--_-___.__ 37

muttistriata...... ......... 9,10,14,15,16,34

nimia....... ____________---_-______- 9

nagaoi..--. .-.----... -----. ------ 37

nattheimensis....... ___--___----__-_____ 9

nipponensis...-------------------......... 9

nuwokensis.... ___.-------_--_--____---_ 37, pi. 6

opercularis ...-.----------------. __ -_ 33,37

otukae.. -------------------- 18,19,30

picoensis... ................ 28,32,33

chinkopensis..--------------- 29,30,33,34,35

kinoshitai. 29,30,31,32

pilkaensis.................... 17,18,21,28,32

pseudislandica....------- 23,29,30,31,32,33,34

arconis____--______ .____ .__ 31

plafkeri ... .. ....... 18,30,32,35

pugetensis.....---.-------------- 14,15,24

rubida.. -. 21,22,23,24,26,28,29,31,33 

hindsii. 21,22,23,24,28,29,30,31,33 

jordani--..------------------------ 22,23,30

prerubida ......_..------_-_------_- 24

satoi 9

sayana... _____.._____.____--___------_ 37

sinuosa.------..-------------------------- 9

splendens. __________.__ _____--_--- 2,9

sguamata.-. _---______ _-- - 9

suprasilis crespusculi___ ______________ 9

tauroperstriata-.-- ----------- 10,15,16,25,34

alternicostata----- __---___________ 9

tegula,...-------------------- .______..__ 9

tigrinus...-------------------------------- 20

53
54 INDEX

Page 

Chlamys Continued

tjornesensis.-------------------- 16,17,25,28,34

trinitiensis. ------- 18,19,20,21,28,29,30

tugidakensis -- _______________ 40

»aria ----------------------------------- 9,10

wainwrightensis... __________ 16,17,28,33,34,36

washburnei.----------------... _ _ 36,37, pi. 1

sp.------------------------------ S6, 37,pis.6,14

(Chlamys). --------.- -------- 9,13,14

--------- #4,pis.20,21,23,24

- . - $6, pi. 18

unalaskae_. __--__ -___ _- #7, pi. 20 

cosibensis.-..... ............___.- 25

hanaishiensis________ 29, pis. 9,10,11,16

amchitkana....--_ 50,pis. 12,13,14,15,22

islandica-.-... _________. 14,33,34,pi. 24

albida.... __________________-__ S6

erythrocomata..____.__...__ S6,pl. 21 

 33, pis. 18,19

____________ SB, pis. 13,15,17,18

powers..__________---- SB, pi. 16

thulensis________________. 34, pi. 18

- - 28, pi. 11

kinoshitai.-...... __________ f9,pl.24

pseudislandica. _____________ 3/, pis. 19,20,23

arconis.... _________________. 33,pi.23

plafkeri.------------------ SS, pis. 12,13

rubida... .......... _____ 27,pis. 20,22

hindsii------- 23,pis. 16,18,19,20,21,22,24

jordanL..---- -_-----__-- SS, 23, pis. 22,24

prerubida.. ______________ £3,pi. 11

wainwrightensis--.--- ____ 27, pis. 18,19,23 

("Chlamys") breidavikensis ----------- /6,pl.25

chaixensis----- __________________ ;s, pis. 9,10

coa.«.._ ______ 17, pis. 14,15

middletonensis- ________ 18, pis. 12,13,14,15

cosibensis..-- _________________ /7,pl. 11

gloriamaris________________________ 16

harmeri- --- ______________ 15, pi. 24

hastata _____________________ /4,pl. 24

fterzcJMj _- _-__ _______- /4,pl. 21

 _-_ _-- /S.pl.10

------------------ 15, pi. 22

tauroperstriata- _____________________ 15

tjornesensis...... __________________ ie,pl.25

trinitiensis.--... _____________ 20,21,pi.8

(Flexopecten) schafferi.. ________________ 11

(Leochlamys) _____________________ 9

columbiana...- _________________ 11

tugidakensis --- 9,/O,11,14,29,32,pis. 7,8 

(Manupecten) pes-felis. _____________ 12,13

(Swiftopecten)----------,--------.- 3,11, pi. 3

donmilleri-.-- ____________!!, IS, 13, pi. 3

kindlei- ______________________________ 12,13

sw//.L ----_-----__-.- -_ 11,12,13

kindlei-.- __________________13, pi. 3

pittukensis. ______________________ 13

(Chlamys), Chlamys. - --- .. 9,13,14

alexandri, Pecten______________________ 9

ashiyaensis, Pecten---- ____________________ 37

beringiana, Chlamys---- __ 24, pis. 20, 21, 23, 24

colvillensis, Chlamys.. ___________ 26, pi. 18

ffram, Chlamys --- ______________ #6

strategus, Chlamys.-,- ____________._ ;_6

unalaskae, Chlamys.. ___________ £7, pi. 20

beringianus, Pecten.. _______________ ___ 17

clintonius, Pecten-. _____________________ 18

rappahannockensis, Pecten-.----- ___ 18

cosibensis, Chlamys. ______________________ 25

erythrocomatus, Pecten-- __________________ 1,36

fissicosta, Pecten________________________ 38

grunskyi, Pecten.-------- _____________ 39

hanaishiensis, Chlamys..----. 29, pis. 9,10,11,16

amchitkana, Chlamys __ 30.pls.12,13,14,15,22 

hastatus, Pecten.. ____________________ 14

albidus, Pecten- ___________________ 36

(Chlamys), Chlamys Continued 

hastatus hericius, Pecten......

hindsii, Pecten..... - .

ingeniosa, Pecten..........

navarchus, Pecten.........

strategus, Pecten........-.

Page

. 14

.- 21 

. 25 

.... 21

.--- 26 

hericeus, Pecten... ....-_ - -- 14,24

albidus, Pecten.. ------....-....... 36

hindsii kincaidi, Pecten....---- --- - 23

islandica, Chlamys.............. 14,33,34, pi. 24

albida, Chlamys. ___ __ 36 

erythrocomata, Chlamys.........-... 36, pl.21

islandica, Chlamys.....__ S3, pis. 18,19

kanagae, Chlamys.--.... 35, pis. 13,15,17,18

powersi, Chlamys...... .. ...... 85, pi. 16

thulensis, Chlamys....... _____ 34, pi. 18

islandicus, Pecten...-................. 30,31,33

beringianus, Pecten....--...---------- 26

picoensis, Pecten___ ____ _ 28,29,34

pugetensis, Pecten... _ 15

jordani, Pecten.---------.- ... - __---_ 22

kindlei, Pecten.- ______ .. 13

lioicus, Pecten.... _ -------- - 2,19

picoensis, Chlamys..-------_ ____ #8

chinkopensis, Chlamys.--- #8, pi. 11

kinoshitai, Chlamys______-_ $9, pi. 24

proavus, Pecten.-------_ - 39

pseudislandica, Chlamys-------- 31, pis. 19,20,23

arconis, Chlamys.... _______-- 33, pi. 23

plafkeri, Chlamys.............. 3#, pis. 12,13

rubida, Chlamys...--------------- SI, pis. 20,22

hindsii, Chlamys.. _________ _-- #3, pis.

16,18,19,20,21,22,24 

jordani, Chlamys.---..---- ##,23, pis. 22,24

prerubida, Chlamys... ____ _ ______ US, pi. 11

sespeensis, Pecten .__________ 38

tdfldSSCVitSCill f JrCCtCfl-- ____----_-._--------- 9

venturaensis, Pecten.___________ 28,29,34

wainwrightensis, Chlamys....... #7, pis. 18,19,23

washburnei, Pecten......____ . 36

("Chlamys") breidavikensis, Chlamys...... 16, pi. 25

chaixensis, Chlamys... _____________ 19, pis. 9,10

coatsi, Chlamys...... _-__ ------ 17, pis. 14,15

middletonensis, Chlamys.- 18, pis. 12,13,14,15 

cosibensis, Chlamys..-...... 17, pi. 11

gloriamaris, Chlamys ______________ . 16

harmeri, Chlamys.-----------... ____ 15, pi. 24

hastata, Chlamys.. _.-__________ 14, pi. 24

hericius, Chlamys..... ________ 14, pi. 21

lioica, Chlamys__--_______._____-___- 19, pi. 10

pugetensis, Chlamys- _________-- 15, pi. 22

tauroperstriata, Chlamys....-- __-___ 15

tjornesensis, Chlamys...--- _____- 16, pi. 25 

trinitiensis, Chlamys___________ SO,21, pi. 8

Chukotsk Peninsula _____________________ 3

cinnabarina, Ostrea-....---- _.______-..- 33

clallamensis, Pecten (Propeamusium)---.----- 7

Clinocardium meekianum...-- ___------------ 32

Clinopegma stantoni. ____________________ 43

clintonius, Pecten (Chlamys)--... _________-- 18

Placopecten _______________ __-- 18

rappahannockensis, Pecten (Chlamys). 18 

coatsi, Chlamys---------- - ---- 17,18,26,30,31

Chlamys ("Chlamys) ____ . 17, pis. 14,15

middletonesis, Chlamys.--.- 17,18,19,26,31,32

Chlamys ("Chlamys")-.-18, pis. 12,13,14,15

columbiana, Chlamys (Leochlamys).----------- 11

Pecten.- ____-__-.______________.--. 9

colvillensis, Chlamys (Chlamys) beringiana.86, pi. 18 

Concept of variability-.--------- ---------- 4

coosensis, Patinopecten (Lituyapecten) ____-__ 41

s, Chlamys-. -- -- - 11,17,18,20, 

21,24,25,26,28,29,34,35 

Chlamys cosibensis------- ... -------------- 17

(Chlamys).------- --------------- 25

("Chlamys")... ---------- 17, pi. 11

Pecten------------------------- ------- 17

Pecten heteroglyptus --------------------- 17

Page 

cosibensis, Chlamys Continued

cosibensis, Chlamys.-..---------___ 17

heteroglypta, Chlamys... ................ 17,19

costellata, Chlamys......-...-.............__ 33

costulata, Molleria............................ 20

crespusculi, Chla mys suprasilis.. 9

Crytonatica........ 13

Cyclocardia... _ 43 

Cyclopecten.... ------- - - - 5,6

imbrifemm . 5

pUStulOSUS............--.-....---.-------- 5

(Delectopecten) greenlandicus.... 8

randolphi.-......_ 5

(Pecten) pustulosus. 5

Pseudamussium... .. . 6

D

daishakensis, Chlamys..... _----------------- 9

davidsoni, Pecten..- _-___ 7

Pecten (Pseudamusium).......----- 7

Polynemamussium .. . .7, pi. 5 

Propeamussium (Parvamussium)......... 7

decemnaria, Chlamys......... .... .... 18

Delectopecten.--.. 5,7,8 

lillisL... 5

maddreni.......... 5,pis. 4,5

peckhami...- _ ___ - - 5

pedroanus.-..- _-_- ____ 5

polyleptus....- -.-__ - _-._ 5

randolphi---- ------- -- 5

(Delectopecten), Palliolum......-- 5

greenlandicus, Cyclopecten..--.. ------ 8

randolphi, Cyclopecten.-.. 5

demissa. Ostrea....- - 33

diegensis, Pecten..------- _____- _-_____ 10

disparatus, Pecten........ __-_ 14

Distribution ofmollusks...---- --- 3

donmilleri, Chlamys (Swiftopecten)---- 11,1^,13,pi. 3

E

eggenburgensis, Chlamys gloriamaris.... - - 9

elongatus, Chlamys....... 9

empirensis, Acila........... __ -------- 43

Epitonium atwoodi......... ---------- 40

erythrocomata, Chlamys...------- ------. 29,30,32

Chlamys islandica--..---- 28,29,30,33,34,35,36 

(Chlamys) islandica....----- -- 36,pi. 21

Pecten (Chlamys)----------------------- 1,36

fabricii, Pecten 33

fissicosta, Pecten (Chlamys)... - 38 

(Flexopecten) schafferi, Chlamys. ____ 11 

Fortipecten --- 3,40,^,43

hattae...- -- - 43,44

kenyoshiensis.--.---- _ _ 43,44

mollerensis.------ ___._-_ - 43,pis. 4,5

pittunensis..----- - -___- 43

takahashii.------ --- -- - 43,44

(Fortipecten), Pecten----.------------------- 42

hallae, Patinopecten-------- _ _ __-- 44

Pecten ..----- - --------------- 44

fucanus, Vertipecten.... 38,40

G

Geographical subspecies. ---------- ___-_ 4

gerardii, Pecten..... 19,20

gigas plana, Amussiopecten.............------- 43

glacialis, Bathyarca. -. - - __ 3 

gloriamaris, Chlamys _ 17,25

Chlamys ("Chlamys")--.- _ 16

eggenburgensis, Chlamys.----------------- 9

glyptus, Pecten.---. ___-_-_----_ 37

graui, Chlamys beringiana.- . _. 25,26,32

Chlamys (Chlamys) beringiana--.- %6 

greenlandicus, Cyclopecten (Delectopecten)... 8

Pecten..-- ------ --------------- 7,8
INDEX 55

Page 

groenlandica, Arctinula, ________________ 7,8, pi. 4

groenlandicum, Palliolum.--... ___._________ 8

Palliolum (Arctinula)... ________________ 8

grunskyi, Chlamys. ______________________ 38

Pecten (Chlamys) _____________________ 39

Qubik Formation...._____________ 3

H

hallae, Fortipecten............... __________._. 43,44

Patinopecten (Fortipeden)................ 44

Pecten (Aequipecten)... ___...___________ 44

(Fortipecten) ... _______________ 44

(Plagioctenium)-.... _______..._._ 44

hanaishiensis, Chlamys... 23,24,26,28,29,30,32,34,35 

Chlamys (Chlamys)....... __ 29,pls.9,10,11,16

amchitkana, Chlamys....... __.._.__ 23,29,30,32

Chlamys (Chlamys).---30, pis. 12,13,14,15,22 

harmeri, Chlamys. -... .______________ 10,15,34

Chlamys ("CWamyg") -- ---------- 15, pi.24

hashimotoi, Patinopecten...... _____.__ __.... 42

hastata, Chlamys.- ____.-._______ 14,15,21,24,37

Chlamys ("Chlamys")................ _ 14, pi. 24

hericia, CMamys................. _________ 14

hericius, Chlamys.. _________________ 14,15,21,24

Chlamys ("Chlamys")-.---------- 14, pi. 21

pugetensis, Chlamys... ____________________ 15

hastatus, Pecten..............._...._..._.. __ 14,15

Pecten (Chlamys).-------- ______________ 14

(Pecteri).. -- .--.-.- __________ 14

albidus, Pecten (Chlamys).-... ____________ 36

Pecten (Pecten).-...... _______________ 36

hericius, Pecten (Chlamys). _______________ 14

hindsii, Pecten (Chlamys)........ _______ 21

ingeniosa, Pecten (Chlamys)., ___________ 25

navarchus, Pecten (Chlamys)... ......... 21

pugetensis, Pecten (Pecten)..... _____.___.. 15

strategus, Pecten (Chlamys) __________ _ _. 26

healeyi, Patinopecten......... _____..________ 42

hericeus, Pecten (Chlamys)............... _____ 14,24

navarchus, Pecten... ________________ 21,22

strategus, Pecten.. ________________________ 26

hericia, Chlamys hastata...-.. _________________ 14

hericius, Chlamys....----.--.................. 21,24

Chlamys hastata.... _______________ 14,15,21,24

("Chlamys") hastata... ___________ _ .$, pi. 21

Pecterc________________________ 14,15,22

(Chlamys) hastatus ----------------- 14

albidus, Pecten.. __________________________ 36

Pecten (Chlamys).----.- ----- _-..- 36

heteroglypta, Chlamys cosibensis... __________ 17,19

heteroglyptus, Pecteft-_____-_._._______________ 17,28

cosibensis, Pectefl_________________________ 17

hindsii, Chlamys.- ________________________ 22,26

Chlamys islandica..-. __________________ 25

rz-b.da_ __________ 21,22,23,24,28,29,30,31,33

(Chlamys) rubida..................... us,

pis. 16,18,19,20,21,22,24 

Pecten_________________________,_ 21,22,23

(Chlamys) hastatus...-..... ___________ 21

(Pecten) .sZand.cz-s1 - _________________ 21,28

kincaidi, Pecten (Chlamys) ------------- 23

navarchus, Pecten....................____. 21

hoskynsi, Pecten....... _ _____________________ 5

Propeamussium...... ___________________ 5

humphreysi, Pecten....... .-._______________ 10

hybrida, Ostrea__-__.____________ __________ 8

Iceland_---------------_-___________________ i

Identical variants of species________________ 4

imanishii, Chlamys....... _____________________ 33

imbriferum, Cyclopecten__ _____________________ 5

incomparabilis, Pecten.. ______________________ 7

ingeniosa, Pecten (Chlamys) hastatus-. ________ 25

insculpta, Chlamys islandica---.________--.____ 33

intuscostalum, Pecten.-___-_________________ o

Polynemamussium.._ _____________________ o

intuscostatus, Perfeft_-____-___________________ 6

Page 

islandica, Chlamys.-------- 1,3,14,16,17,2],22,23,

25,28,29,30,31,32,33,34,35,36 

Chlamys islandica___.____________ 35

(Chlamys). .-___________--__ 14,33, 34, pi. 24

islandica.-................ _ 33, pis. 18,19

a.&.<.a, Chlamys --.--------- 27,33,34,35,36

Chlamys (Chlamys)..... _________ 36

behringiana, Chlamys....... __--__-___ 24,26

erythrocomata, Chlamys.... 28,29,30,33,34,35,36

Chlamys (Chlamys)...... _______ 36, pi. 21

hindsii, Chlamys ----------------- 25

insculpta, Chlamys -------- _______. 33

islandica, Chlamys.... ______________ 35

Chlamys (Chlamys). ________ 33, pis. 18,19

kanagae, Chlamys_____.-___-- 28,29,34,35,36

Chlamys (Chlamys) 35, pis. 13,15,17,18 

kinoshitai, Chlamys...... ____-___.-_____- 29

osugii, Chlamys.... ___-___-_-___._ --_-__ 29

power si, Chlamys.... --- _______ 27,31,34,35,36

Chlamys (Chlamys)_ _________ 35, pi. 16

thulensis, Chlamys.. _______________ 35

Chlamys (Chlamys)-... ______ 34, pi. 18 

islandicus, Peden........ _____ 8,14,19,30,31,32,33

Pecten (Chlamys)--------.-__-_____. 30,31,33

(Pecten).. ____________________________ 31,33

behringiana, Pecten.... __________________ 24

behringianus, Pecten...------------------. 1,2

Pecten (Chlamys).--... ___________ 26

hindsii, Pecten (Pecten). -- -- ________ 21,28

jordani, Chlamys_______________________ 22,23

Jordani, Pecten (Pecten).... _--___.___-___ 23

picoensis, Pecten (Chlamys).----------- 28,29,34

pugetensis, Pecten....... ______-.._ _____, 15

Pecten (Chlamys).-----. .... ________ 15

Isocrinus nehalemensis...- -.--.--. ---..- 37 

oregonensis.................... ____________ 37

iwakiana, Chlamys.-.. _---____---__-__-____- 9

jacobaeus, Pecten__--._-_-_____._____--___ 10 

janthostoma, Natica--... __--__-_-____-_-_-.___ 3 

Japan Current____--____--_____-_--___-___ 3

jordani, Chlamys.. _ ___________.-_____._._ 22

Chlamys islandicus... _____________________ 22,23

rubida............. ___________ 22,23,30

(Chlamys rubida ---... ___- 88, 23, pis. 22,24 

Pecten (Chlamys) ________________._ 22

(Pecten) islandicus.-...--. ____________ 23

justiana, Chlamys....... __.--____---___-______ 9,10

e, Chlamys islandica..... ... 28,29,34,35,36

Chlamys (Chlamys) islandica. 35, pis. 13,15,17,18 

kenyoshiensis, Fortipecten.--------... ____-_ 43,44

kincaidi, Chlamys.-- ---- ......... 22,23,30

Pecten...---- ........................... 23

(Chlamys) hindsii__._._______- 23

Chlamys (Swiftopecten)........ .. ..... 12,13

(Swiftopecten) swifti......._____ /3,pl.3

Pecten (Chlamys)... __.--____-_. ____-.. 13

(Manupecten)-..-..-.......... __.-.__ 13

(Pallium) swifti..- .. .......___ 13

(Swiftopecten) swifti..-..... -......... 13

kinoshitai, Chlamys.- -..... ___..--_____. 28,32

Chlamys islandica.. . -... ...----.. . 29

picoensis..-..-.-- ____________ 29,30,31,32

(Chlamys) picoensis... ____________ 29, pi. 24

kitamurai, Chlamys-- .--------------------- 11

Nanaochlamys--.------------- ------------ 11

Kivalina.------------------------------------- 3

Kotorapecten- ________________ 40,42,43

Kotzebue Sound.._._-____----.__--_-__---___. 3

Kresta Bay..-------------------,-_.-------__- 3

L

achenbruchi, Vertipecten. ______ 9. 40, pis. 1,2

laevis, Pecten tigrinus.-................ ___ 19,20

Leochlamys . - . 9,10,11,14 

(Leochlamys), Chlamys..........__ ______ 9

columbiana, Chlamys. _.__ - 11

tugidakensis, Chlamys.- 9, JO, 11,14,29,32 pis. 7,8

Lepas balanus.--..--.................. _-_- 33

levis, Pecten (Propeamusium). -_ 7 

lillisi, Delectopecten... _ ___ _ __ 5 

limatus, Pectenpusio......-...--..-.......... 10

lioica, Chlamys................. ...... 19,20,21

Chlamys ("Chlamys"). ---- -- 19,pl. 10

lioicus, Pecten (Chlamys)..--. -- __ 2,19

Pecten (Pecten)- _______________ 19

lituyaensis, Patinopecten (Lituyapecten)....... 2,41

Lituyapecten __ _ ._ 1, 41, 42

(Lituyapecten) coosensis, Patinopecten.- 41

lituyaensis, Patinopecten. _-_--._ .._. 2,41

poulcreekensis, Patinopecten-............. 37

purisimaensis, Patinopecten.- ----------- 41

yakatagensis, Patinopecten-...- -.--.---. 41 

lividus, Pecten........._ __ _ _-___ 9

longolaevis, Chlamys......-.-...---....------- 17

M 

A-"ocoma-__-_----------- __ __ _ 43

Mactra.-------------------------------------- 34

maddreni, Delectopecten----- __- 5, pis. 4, 5

Manupecten.. - _____ 12

(Manupecten) kindle.i, Pecten----- _ _____ 13

pes-felis, Chlamys.-.-----. ___--_.____-____ 12,13

Marianna Limestone___ _ __ __ 2 

Masudapecten..-.- _.-.-__-_-.--___ 40,43,45 

(Masudapecten), Patinopecten -------------- 44

matchgarensis, Chlamys..-............... ______ 37

matnumoriensis, Miyagipecten......... ____ 44

meekianum, Clinocardium.................... 32

merriami, Area... . --_-_-___--___---_____ 40

middendorffi, Mytilus.......-....--....---_..- 12,13

middletonensis, Chlamys coatsi_.. 17,18,19,26,31,32

Chlamys ("Chlamys") coatsi. 18, pis. 12,13,14,15 

Migration patterns of mollusks.-------- ___ 3

Mimachlamys _______----____---_.----- ---- 9

Mirapecten. --. -..----_-..--..--.. ..-..... 9

thadnumi- ________________________________ 9

Miyagipecten........ . - -.. -.. .... 44,45

alaskensis.------- ______ _____^ __________ 45, pi. 6

matsumoriensis------------------------ 44

saromensis ________ ________________ ______ 45

Mizuhopecten----------------------- 40,^,42,43

(Mizuhopecten), Patinopectin.---.------ -- 41

skonunensis, Patinopecten ___________ 42,pis.4,6

mollerensis, Fortipecten __________________ 43, pis. 4, 5

Molkria costulata. -------------------------- 20

(Monia), Pododesmus^------------------------ 13

multistriata, Chlamys-.-.--.---- 9,10,14,15,16,34

nimia, Chlamys ------------------------ 9

multistriatus, Pecten- ____.___________-__-__-_- 16

Mya---------------------------------- 43

arenaria-.-- ..---.---...-..---..-.---..-- 18 

Mytilus middendorffi --------------------- 12,13

N

nagaoi, Chlamys.----------------------------- 37

Nanaochlamys------------------------ -_-__- 11

kitamurai------------------------------- 11

notoensis ------------------------------ 11,12

otutumiensis----------------------- 11,12,13

Nassarius ------- ----------------------- 42

whitneyi-- ___ _--.-.----- --__- ------ 42

Natica jantnostoma.-------------------------- 3

nattheimensis, Chlamys- _____ _ ----__--_-- __ 9

nzvarchus, Pecten hericeus-----------~ -------- 21,22

Pecten hindsii--------------- ------------ 21

(Chlamys) hastatus _ ___.--_-___----_-_ 21

nehalemensis, Isooinus,- -------- -______- ._ 37

Neilhea quinquecostatus _ _ _...-- ----- ---_-- 2

nevadanus, Pecten . -..--- ...- ----------- 38

Vertipecten- -------------- _ ___-_--.-- 40

nimia, Chlamys mullistriata-.----------------. 9

ninohensis, Patinopecten yamasakii---------- 42
56 INDEX

Page 

nipponcnsis, Chlamys.--------- ______________ 9

Nipponopecten.. .............................. 40,43

Nome, Alaska__________________ 2,3 

Nomenclature, complexity of pectens.______ 2

notoensis, Nanaochlamys. ____. ______ 11,12 

Pecten____________________ 11 

otutumiensis, Nanaochlamys- ________ 11,12,13

nuwokensis, Chlamys..---. _._________ S7,pl.6

O

Okhotsk Sea-------...---- ---_-______-___ 1

Oligocene,

Asiatic fauna...._-------..__-__._____ 3

Marianna Limestone._________-_._._ 2

opercularis, Chlamys____..____.._______ 33,37

Pecten________________._ 33

oregonensis, Isocrinus...- _--_____-.._._ 37 

Patinopecten...--.-........ .__-__-..______ 41

Ostrea cinnabarina.. _________ ____ 33

demissa_.. _____..______________... 33

hybrida,--. ___________________ 8

pes-felis_.......................___. 12

pusio---.----.---.- _______________ 16

tigiliana.-.-.- ________-_________ 40

osugii, Chlamys islandica..-....._____._ 29

otukae, Chlamys--... __..__________ 18,19,30

otutumiensis, Nonaochlamys notoensis.- __ 11,12,13 

Pecten (Swiftopecten) - .. _ _________ 11,12

Palliolum.--.- ____..._. _______________ 7,8

groenlandicum -. _,----_-__-_.___________ 8

(Arctinula) groenlandicum.... .__..___ 8

(Delectopect en) -.____._._______________ 5

(Palliolum (Arctinula)), Propeamusium- _____ 7

(Pallium) swifli kindlei, Pecten...__...___ 13

Panomya..- ______,------._____.___.___ 43

Parallelism in Pectinidae,..-- __ _ __ _ _ 2

Parvamussium________________.____ 6

(Parvamussium) alaskense, Propeamussium.-. 6

davidsoni, Propeamussium. -_-__.____. 7

Patinopecten...------------ ________ 38,40,41,42,43

caurinus... 

hashimotoi.

oregonensis_____.___.______

propatulus..... _____________...

skonunensis. __.-._-_________________

yamasakii... . ____________________

ninohensis.-------------- _______....

(Fortipecten) hallae- .-__----____-____-__

(Lituyapecten)- _________________________ 41,45

coosensis------ ____._.___________ 41

lituyaensis...... ______________..__ 2,41

poulcreekensis________---.__.-____ 37

purisimaensis_----_.____--____ 41

yakatagensis- _______________ ________ 41

sp - 4/,pl. 6

(Masudapecteri) _.._________________ 44

(Mizuhopecten). __________________ 41

skonunensis--------------------- 42,pis. 4,6

(Patinopecten)-------- _________________ 41

caurinus..--.---------------------- 4/,pl. 4

(Patinopecten), Patinopecten-.-------------... 41

caurinus, Patinopecten... _-_________._.. 4/,pl. 4

rhytidus, Pecten--------------------------- 44

pealeii, Pecten. _._-__.---_--_--_____.____. 33

peckhami, Delectopecten.---.... __...____ 5

Pecten.----------------------.--.-- 10,11,41,43

alaskensis----- _____________________ 6,7

albicans. 

albidus..

attiplicatus_. 

arat us........

asperrimus.... 

assiniboiensisbenedictus__ 

boringuense.--

10

35

10

15

18

9

38

10

10

Page 

Pecten Continued

branneri. ________________.. 38,39

calamitus__________ ______.-_--- 7

caurinus---------------------------------- 40,42

columbiana.........-_ __...__ 9

cosibensis... __________.---__-_________-. 17

davidsoni...... .. ._ -----_____ 7

diegensis____...__--._______ 10

disparatus........------------ .... _____ 14

fabricii.. .- ........................ 33

gerardii-.................................. 19,20

glyptus.-.-. --...----. -....------- .- 37

greenlandicus----------------------------- 7,8

hastatus.-------------------------------- _ 14,15

hericeus navarchus _ 21,22

strategus--.------ ....-_---___ .__-_. 26

hericius ............................. 14,15,22

albidus____________________ 36

heteroglyptus....... --- _ 17,28

cosibensis.-------------------------_ 17

hindsii . . . 21,22,23

navarchus..-__---- 21

hoskynsi------ ._____-.-___--_ _ 5

humphreysi------------_..._..__. 10

incomparabilis-----------...--- _------_ 7

intuscostatum..------ __________-.._ 6

intuscostatus-----. ____-__--_--. _______ 6

islandicus. ------------ 8,14,19,30,31,32,33

behringiana--------------------------- 24

behringianus--- ... ----------- 1,2

pugetensis---------------- ...-------- 15

jacobaeus----..------------- ...___._--_

kincaidi____.._.__-__-__--_-_-_-_-_-_-_

lividus-.--.-- ___-__-____-_-_-.-_-_-_--

multistriatus......._-__--___--

nevadanus-------------... _-_______-_.

notoensis____.____-_-__-_--__-_--_-_-_

opercularis _____._-____-__.___-_._

plebejus ..... .. ..... ... ------------------

poulsoni.. --- ... ___ _ _ _____________ _ 2

propatulus ... _ __._.___ _ ____._-___-___ 2

pusio. -------- --- .- .-- -- ---. . --. ------ 9,10,16

limatus---. ... _______--_-___-_-----___ 10

striatus--- ___ ......... _ 10

rubidus- -------------------------- 2,21,22,24,33

rupeliensis... ...... ... ____-_-_-__._-._. _ 10

septemradiatus- __ _ 8 

strategus---- ...... . __ - _ - __ - _ - _ 27

striatus..-.---.----------- ... ___-_-___ _ _ 10,15

substriatus. _ ______._-__-__--_-__-___-___ 15

sivifti. ---. -_____-___-_-_---_ _ __._-_- _ - 11

piltukensis.-- _ __-_---_-------------_ 20

takahashii ___ _ ______ _ ___ ___ 42

tigrinus .... ._--._ __ _ -___-_.____-_-.-__ 19,20

laevis- ---------------------------- 19,20

tokunagai..------ _ _ _ ___._-_ _ __--__ 44

turpiculus- ---------- ... --------- --.- ----- 17,28

varius. .. __ _______.____-___-_---_-_---_____ 10

yessoensis ___________ _ _____ . 40,41,42 

sp-__-__.__ _ __.____-_______--_--__-__--. 26

(Aequipecten) hallae . ___ __. __ 44

(Chlamys) alexandri 	9 

........... 37

..-._._____ 17

-_- -___ 18

-_ _---- 18

_______ 1,36

........... 38

_ ___ __ 39

_.___-___.. 14

_-_____-..- 36

_____-_---_ 14

_______ 21

__-.__.____ 25

_.--_-_.._- 21

___________ 26

hericeus _ _ __ ___-_-__ ___ __ 14,24

hericius albidus .. --...... __. ._. .-._. 36

beringianus.-- ____-

clintonius.__.-- -

rappahannockensiserythrocomatus .....

flsr'osta...----------

grunskyi___.---_-- 

hastatus_----------

albidus___-_.___ 

hericius-- _ __- 

hindsii..- ________

ingeniosa.......---

navarchus--- -___ 

strategus ---------

Page

Pecten C ontinued

(Chlamys) Continued

hindsii kincaidi _____ __. 

islandicus___-.-._______. 30.

picoensis..... _-___ ____ 28,

pugetensis. .-..-.----...-.-.........

jordani......... _____-_.__

kindlei.. _----__------_-_-----______-_-

lioicus. ------------.--.-.-----------

proavus___._- _-- __-_-_ _ _ 

sespeensis.------ ___. - _-_

tanassevitschi______________________

venturaensis...--------------------- 28,

washburnei.-----------... _________

Sp- _ _ - -

(Fortipecten)......._ _ _.-__-.__

hallae.--__ -- ___-_ _.

(Manupecten) kindlei ------------------

(Pallium) swifti kindlei.------------------

(Patinopecten) rhytidus... ___ ___________

(Pecten)....... .

beringianus----... -__ _ -_-___._

albidus-____ _...

pugetensis-.-- ... 

islandicus-... ..... ____

hindsii------ -___--

Jordani.- -. ....

lioicus-...-------------

(Pla&ioctenium) hallae. ._..

(Propeamusium) alaskense.

alaskensis___ _.___

clallamensis -___--

23

31,33

26

29,34

15

22

13

2,19

39

38

9

29,34

36

26

42

44

13

13

44

11,44

27

14

36

15

31,33

21,28

23

19

44

6

6

7

7

._______________ 7

(Propeamussiu m).------------------------ 6

Pecten (Pseudamusium) davidsoni------------- 1

vancouverensis..---------------------- 5,7

(Pseudoamussium) alaskensis- __________ 6

(Swiftopecten)..-.------- _ __ _______ 11

otutumiensis---... _______ ___ ---___- 11,12

(Vertipecten) -------------------------- 38

rhytidus___.__ -. _..__________ 44

yneziana subyneziana.-.- _____________ 38

(Vola) byoritzuensis... _ _ 10 

(Pecten) beringianus, Pecten ._.. _________ 27

hastatus, Pecten__--__ ___________ - 14

albidus, Pecten.__ _____-._-_ 36 

pugetensis, Pecten...-.... __________ 15

islandicus, Pecten. _ _ 31,33 

hindsii, Pecten. . 21,28

Jordani, Pecten------- _ 23

lioicus, Pecten.--.----------- ...__-__.__-_ 19

pecten........ ___ _-__ __ 11,44

pustulosus, Cyclopecten.------------------ 5

pedroanus, Delectopecten.---- ..._._-_ _-___ 5

perrini, Spondylus.....- ___.____ _ ------ 37

pes-felis, Chlamys (Manupecten)------ ..._ - 12,13

Ostrea.----------------------------------- 12

Phylogeny of pectens.-- -_ -- ------- 2

picoensis, Chlamys.. ------------------ 28,32,33

Chlamys (Chlamys). ______ #8

Pecten (Chlamys) islandicus..------ 28,29,34

chinkopensis, Chlamys.------- 29,30,33,34,35

Chlamys (Chlamys)------------ 88, pi. 11

kinoshitai, Chlamys..------------- 29,30,31,32

Chlamys (Chlamys)---------------- 29, pi. 24

pilicaensis, Chlamys -------- 17,18,21,28,32

piltukensis, Chlamys (Swiftopecten) swifti --- 13 

Pecten swifti----------------------------- 20

piltunensis, Fortipecten----------------------- 43

Placopecten. ---------- - 18,37

clintonius----------- -__.____- _______ 18

plafkeri, Chlamys pseudislandica- _ 18,30,32,35

Chlamys (Chlamys) pseudislandica S2, pis. 12,13

(Plagioctenium) hallae, Pecten- -------- 44
INDEX 57

Page

--_._______ 43

__________ 37

____________ 44

___---_____ 3

___________ 4

 __- .- 3

. _._-___ 13

_________ 3

___________ 5

Polynemamussium,--- -- ___ _________________ 5,6,7

alaskense.. ----------------- ------------6, 7, pi. 6

calamitus. -------------------------------- 7

davidsoni ----------------------- _ _-- 7, pi. 5

intuscostatum. ____________________________ 6

riversi. __ ________________________________ 7

___________ 6

___________ 7

plana, Amussiopecten gigas... 

Platyodon.... ___________

pkbejus, Pecteii. ____________

Pleistocene,

distribution of mollusks.

geographic subspecies.-.

Gubik Formation. ______

Pododesmus (Mania) ________

Point Barrow, Alaska.______

polyleptus, Delectopecten-----

popofensis, Vertipecten..-- ________ ____ 3S,40,pls.l,2

Population concept.-. _ _____________________ 4

porterensis, Vertipecten ... _________ _________ 38,40

poulcre&kensis, Patinopecten (Lituyapecten)-.-- 37 

poulsoni, Pecten. ............... ___ .___-_---__ 2

powersi, Chlamys islandica. ... _______ 27,31,34,35,36

Chlamys (Chlamys) islandica.---------- 35,pl.l6

prerubida, Chlamys rubida... ------ ____ _ __ _ 24

Chlamys (Chlamys) rubida..- __________ S3, pi. 11

proavus, Pecten (Chlamys). ...... ........... 39

propatulus, Patinopecten.--------------------- 41

Pecten.-. .-- .... _ ____ _ ____ _ ____ 2

Propeamusium (Palliolum (Arctinula)).--- _ 7 

(Propeamusium) alaskense, Pecten--- ------- 6

alaskensis, Pecten ... ___ ___________________ 6

clallamensis, Pecten _ -__-___-_____ _ - 7

levis, Pecten .... ________________________ 7

riversi, Pecten...------ ------------------ 6

waylandi, Pecten-.- _______________________ 7

Propeamussium. _____________________________ 2,6

hoskynsi..-- _ ___________________________ 5

(Parvamussium) alaskense. ___ _ _________ 6

davidsoni ...... ____________ _ _________ 7

(Propeamussium), Pecten _______ ______________ 6

Pseudamusium andersoni.,-- -------------- 8

binominatus ______________________________ 8

(Pseudamusium) davidsoni, Pecten..--- ----- 7

vancouverensis, Pecten _ _______ _ ________ 5,7

Pseudamussium.. -- ___ ____________________ 6,7,8

(Cyclopecten)-.-- ... ________ ____ __ _ 6

pseudislandica, Chlamys..-.---- 23,29,30,31,32,33,34

Chlamys (Chlamys).- _ _____ _ 3^, pis. 19,20, 23

arconis, Chlamys.------------------------- 31

Chlamys (Chlamys)--.---------- 33, pi. 23

plafkeri, Chlamys...-------.------. 18,30,32,35

Chlamys (Chlamys) ... _____ 35, pis. 12, 13

(Pseudoamussium) alaskensis, Pecten...--- - 6 

Pteriids ____________________________________ 2

pugetensis, Chlamys _ ___________ _ ______ 14,15,24

Chlamys hastata. .-_______ _ __________ _ _ 15

("CWomys")------------------- 15, pi. 22

Pecten islandicus ....- ... __________________ 15

(Chlamys) islandicus-- ------------ 15

(Pecten) hastatus .... __________________ 15

purisimaensis, Patinopecten (Lituyapecten) ___ _ 41

pusio, Ostrea _ ______________________________ 16

P«rf«n- -_-- - -------- 9,10,16

limatus, Pecten--- __ _ __ __________ _ 10

striatus, Pecten ------------------------- 10

pustulosus, Cyclopecten.-----..---- ___ ________ 6

Cyclopecten (Pecten)------ ------------- 5

Queen Charlotte Islands. 

quinquecostatus, Neithea..

E Pagp>

randolphi, Cyclopecten (Delectopecten). ____

Delectopecten,......... ___ --__ ___ - * 

rappahannockensis, Pecten (Chlamys) clintonius..--.-------.---------____ 18

rhytidus, Pecten (Patinopecten). -............ 44

Pecten (Vertipecten)-----... ____---___-_ 44

riversi, Pecten (Propeamusium)--------------- 6

Polynemamussium______._____ 7

rubida, Chlamys.------- 21,22,23,24,26,28,29,31,33

Chlamys (Chlamys)- ----_____ SI, pis. 20,22

hindsii, Chlamys.---. 21,22,23,24,28,29,30,31,33 

Chlamys (Chlamys) .......S3, pis. 16,18,19,

20,21,22,24 

jordani, Chlamys__ ______________ 22,23,30

Chlamys (Chlamys)--. ______55,23,pis. 22,24

prerubida, Chlamys.-- ___________ 24

Chlamys (Chlamys) ________ S3, pi. 11

prerubida, Chlamys.-. __-_________ 24

Chlamys (Chlamys). _______ 23, pi. 11

rubidus, Pecten...-- __________________ 2,21,22,24,33

rupeliensis, Pecten..-. ______----____-___--._-_ 10

sagai, Turritella ___ _ _ .-___-. 

saromensis, Miyagipecten ...... __

satoi, Chlamys.- ... __ __ _ ____

sayana, Chlamys. ____________ _

Scaeochlamys.- __ _______ __ _

schafferi, Chlamys (Flexopecten) _ 

septemradiatus , Pecten------ _ _

sespeensis, Pecten (Chlamys).--

_ _____ 37

_ _ _ 9 

_ _____ 11

________ 8

__ __ _ 38

-------- 40

shumardi, Acila --------------------------- 39,40

Siliqua...- - -- -------- .- . ----- .,- --. _____ 43

simanense, Polynemamussium... _____________ 6

sinuosa, CMam_/s____-________________________ 9

Sitka, Alaska...--..---------- ------------ 2

skonunensis, Patinopecten- __ ________ ____ 42

Patinopecten, (Mizuhopecten. _______ 42, pis. 4,6

Spisula. ..---- ---------------------------- 13,43

splendens, Chlamys..-------------- . ... _____ 2,9

Spondylus.. . _ ____ ___ ,__ __ __ 37

perrini.. _ _______ _ _____________________ 37

Squamamussium ______ ________________________ 6

squamata, Chlamys...---- _ ___ _ ___________ 9

squamigerum, Amusium. _______ ___ ____ __ 6

stantoni, Clinopegma-.---..--. ______________ 43

strategus, Chlamys beringiana-- ____ _. 18,25,26,27

Chlamys (Chlamys) beringiana... _________ 56

P_c._r..___-____, __________________________ 27

hericeus...... .... ________ __ __ ___ 26

(Chlamys) hastatus ... _________________ 26

striatus, Pec.«r.---__---_____-________________- 10,15

Pecten pusio.-- __________ _ ____ ___ _ 10

Subarctic Current-- ___ ______ _ _______ __ 3

substriatus, Pecten.. . _. _ -. _ -___ 15 

subyneziana, Pecten (Vertipecten) yneziana.--- 38 

suprasilis crespusculi, Chlamys.. ______ _____ 9

swifti, Chlamys (Swiftopecten)-..-- _ __ _ _ 11,12,13

kindlei, Chlamys (Swiftopecten) -------- 13, pi. 3

Pecten (Pallium)--.---------------- 13

Swiftopecten..------.----------------- 13

piltukensis, Chlamys (Su-iftopecten) . ______ 13

Pecten.--- ___ ____________ _____ 20

Swiftopecten.. --------------- ^,12,13,20,25

sw./<j kindlei.- _______-_________-__. 13

(Swiftopecten), Chlamys---. -------------- 3,11, pi. 3

Pecten-.--- ---------------------- 11

donmilleri, Chlamys... ___________ HJ5,13,pl.3

fc.wcfZe., Chlamys. ______________________ 12,13

otutumiensis, Pecten..-. --------------- 11,12

sw./.., Chlamys.----------------------- 11,12,13

kindlei, Chlamys.. ___ _ _ __ ^3,pl. 3 

piltukensis, Chlamys. ----------------- 13

Systematic concept _ .-.-_- 

Systematic revisions of PectinidaePage

4

2

T

takahashii, Fortipecten.------------ ____ __ 43,44

Pecten_______________.__ 42

tanassevitschi, Pecten (Chlamys)---------- _ 9

tauroperstriata, Chlamys...- -- 10,15,16,25,34 

Chlamys ("Chlamys").------------------- 15

alternicostata, Chlamys _ _________ 9

tegula, Chlamys.- ____ _____-_-__.-- 9

TeUina . . 13

thaanumi, Mirapecten...- ___.-_._______.. 9

thulensis, Chlamys islandica __ ____________ 35

Chlamys (Chlamys) islandica- _______ 3^,pl.l8

tigiliana, Ostrea.--- ___-_-_-_--_____--__-.__ 40

tigrinus, Chlamys. _____ _____________ 20

Pecfera - - - 19,20

laevis, Pecten..--._-_____ ___- 19,20 

tjornesensis, Chlamys....- ______ 16,17,25,28,34

Chlamys ("Chlamys")--..---------- 16, pi.25

tokunagai, Pecten... _ 44 

trinitiensis, Chlamys---------- 18,19,20,21,28,29,30

Chlamys ("Chlamys") --_______ 50,21,pi.8

lugidakensis, Chlamys ___- .--__-. _ 40

Chlamys (Leochlamys).- 9, 10, 11,14,29,32 pis. 7,8

turpiculus, Pecten.... _________ _____ 17,28

Turritella sagai... __ _ 43 

Type specimen, definition------ ____ _-_ 4

U

unalaskae, Chlamys beringiana. _______________ 25

Chlamys (Chlamys) beringiana______ 57, pi.20

V

vancouverensis, Pecten (Pseudamusium)------- 5,7

varia, Chlamys.. _____________.-.________ 9,10

varius, Pecten.-.... .--.------------ __.--. 10

venturaensis, Pecten (Chlamys) ____-___ 28,29,34 

Vertipecten. .__-___-_____-__________- ____11,37,38,40

bowersi... _______________.______ 40

fucanus___________________ 38,40

lachenbruchi______.__ 38,35,40, pls.1,2 

nevadanus.----------------- _______.. 40

popofensis... _________________ 35,40, pls.1,2

porterensis_________________ 38,40

sespeensis --- ________________ 40

yneziana.-.- ______________________________ 38,40

Sp....--------------------- ----- 40, pl.l

(Vertipecten), Pecten-________________ 38

rhytidus, Pecten-.______________ 44

yneziana subyneziana, Pecten----. _.__-. 38

(Vola) byoritzuensis, Pecten ---------------- 10

W

wainwrightensis, Chlamys.-- ___ 16,17,28,33,34,36 

Chlamys (Chlamys)....-------- 57, pis. 18,19,23

washburnei, Chlamys ___ 36,37, pl.l 

Pecten (Chlamys)------------------------ 63

waylandi, Pecten (Propeamusium)--.----- _ 7

whitneyi, Nassarius.------------.------------- 42

Yabepecten.--------------- ______________ 45

yakatagensis, Patinopecten (Lituyapecten) ___ 41 

yamasakii, Patinopecten - ______________ 42

ninohensis, Patinopecten---.----------- 42

yasudae, Polynemamussium------------------ 7

yessoensis, Pecten..------------- -------- 40,41,42

yneziana, Vertipecten-------- ---------------- 38,40

subyneziana, Pecten (Vertipecten).-.------ 38

223-848 O - 67 - 6

PLATES 1-25
PLATE 1

FIGURE 1. Wertipeden cf. V. popofensis MacNeil (p. 40).

Figured specimen (USNM 645051, fragment of ?right valve, internal mold, X 2. Tokun

Formation, upper part (Oligocene), Katalla district, Alaska, USGS 4323. 

2. Chlamys(1) washburnei (Arnold) (p. 36).

Figured specimen (USNM 645029), incomplete left valve, X 1. /socn'nws-bearing beds

(early Oligocene), Amchitka Island, Aleutian Islands, Alaska, USGS D47. 

3-8. Vertipecten lachenbruchi MacNeil, n. sp. (p. 39).

Unnamed formation, Acila shumardi zone (middle Oligocene).

3. Holotype (USNM 645031), incomplete left valve, rubber cast, X l)i East tributary to 

Mud Bay, Alaska Peninsula, USGS M1025.

4. Another cast of holotype, different illumination, X 2.

5. 6. Fragments (USNM 645035-36), X l)i Near northeast corner of Unga Island, 

Alaska, USGS 5037.

7. Paratype (USNM 645032), fragment of right valve, rubber cast, X 2#. USGS 5037.

8. Paratype (USNM 645033), incomplete right valve, rubber cast, X 2ji USGS 5037.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE

PECTINIDS FROM ALEUTIAN ISLANDS, ALASKA PENINSULA 

KATALLA DISTRICT (ALASKA)
PLATE 2

FIGURES 1, 3, 5, 6. Vertipecten popofensis MacNeil, n. sp. (p. 39).

Unnamed formation, Acila shumardi zone (middle Oligocene).

1. Holotype (TJSNM 645037), incomplete left valve, X 2. Near northwest corner of

Popof Island, Alaska, USGS 3563. 

3. Paratype (USNM 645039), fragment of ?left valve showing ear, X 2%. Near

northeast corner of Unga Island, Alaska, USGS 5037.

5. Paratype (USNM 645040), fragment of right valve, X V/2. USGS 5037.

6. Paratype (USNM 645038), fragment of left valve, rubber cast, X 1. USGS 3563. 

2. Vertipecten n. sp.? (p. 40).

Figured specimen (USNM 164892), incomplete left valve, rubber cast, X l/^- East 

end of Chichagof Bay in Acila shumardi-bearing beds (middle Oligocene), Alaska 

Peninsula, USGS 3373. 

8. ^Vertipecten popofensis MacNeil.

Figured specimen (USNM 645041), fragment of right valve, rubber cast, X 2%. 

USGS 5037. 

4, 7. Vertipecten lachenbruchi MacNeil, n. sp. (p. 39).

Unnamed formation, Acila shumardi zone (middle Oligocene), near northeast corner

of Unga Island, Alaska, USGS 5037.

4. Paratype (USNM 645034), dorsal fragment of right valve showing ears, X 2J/z. 

7. Paratype, same specimen as pi. 1, fig. 8, X 1, USGS 5037.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 2

PECTINIDS FROM ALASKA PENINSULA, SHUMAGIN ISLANDS (ALASKA)
PLATE 3

[All figures X 1]

FIGUEES 1, 4, 6. Chlamys (Swiftopecteri) donmitteri MacNeil, n. sp. (p. 12).

1. Holotype (USNM 644882), right valve, rubber cast. 1,500 ft above base of Yakataga

Formation (horizon probably middle Miocene), USGS 6694. 

4. Paratype (USNM 644883), incomplete left valve, rubber cast. Near base of Yakataga

Formation (horizon probably middle Miocene), USGS 15437. 

6. Figured specimen (USNM 644884), incomplete left valve. Near base of Chaix Hills

section of Yakataga Formation (horzion probably upper Miocene), USGS 17817.

2. Chlamys (Swiftopecteri) sp. (p. 13).

Figured specimen (USNM 644886), incomplete left valve, rubber cast. Unga Conglomerate 

Mytilus middendorffi zone (middle Miocene), east side of Port Moller, Alaska Peninsula, 

USGS 5046.

3. Chlamys (Swiftopecteri) cf, C. (S.) donmilleri MacNeil (p. 13).

Figured specimen (USNM 644885). Unga Conglomerate, Mytilus middendorffi zone

(middle Miocene) northwest side of Cape Aliaksin Alaska Peninsula, USGS M2132. 

5,7-9. Chlamys (Swiftopecteri) swifti kindlei (Dall) (p. 13).

Figured specimens. Intermediate Beach (middle Pleistocene), Nome, Alaska. 

5, 7. Fragments of left valves (USNM 644889-644890), USGS 5074.

8. Left valve (USNM 644888), USGS 14866.

9. Right valve (USNM 644887), USGS 5313.
PROFESSIONAL PAPER 553 PLATE 3

PECTINIDS FROM ALASKA PENINSULA, SEWARD PENINSULA 

YAKATAGA DISTRICT (ALASKA)
PLATE 4

[All figures X 1 unless otherwise noted]

FIGURE 1. Fortipecten mollerensis MacNeil, n. sp. (p. 43).

Holotype (TJSNM 645047), exterior of left valve. Unnamed formation (horizon probably 

upper Miocene or lower Pliocene), southeast of Point Divide, Herendeen Bay, Alaska 

Peninsula, USGS M2131. 

2. Patinopecten (Mizuhopecteri) skonunensis MacNeil, n. sp. (p. 42).

Holotype (UCLA 39474), exterior of right valve. Skonun Formation (probably late Miocene), 

Skonun Point, north side of Queen Charlotte Island, British Columbia. UCLA loc. 4674. 

3, 4. Patinopecten (Patinopecten) cf. P. (P.) caurinus (Gould) (p. 41).

Figured specimens. Upper part of Yakataga Formation (horizon probably Pliocene), Point 

Glorious, Malaspina district, Alaska, USGS D263 (T).

3. Left valve (USNM 645043), rubber cast.

4. Right valve (USNM 645042), rubber cast.

5. Delectopecten maddreni MacNeil, n. sp. (p. 5).

Figured specimen (USNM 644866), left valve. Near middle of Poul Creek Formation 

(horizon probably late Oligocene), north end of Hanna Lake, USGS 16898. Poul Creek 

Formation (late Oligocene and early Miocene), Yakataga district, Alaska.

6. Arctinula groenlandica (Sowerby) (p. 8).

Figured specimen (USNM 561876), right valve, X 4. Lower part of Nuwok Formation of 

Dall (1919) (horizon probably upper Miocene), Carter Creek, Artic coast of Alaska, USGS 

D50 (T). Nuwok Formation of Dall (1919) (late Miocene and Pliocene), Camden Bay 

region, northeastern Alaska.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 4

PECTINIDS FROM ALASKA PENINSULA, YAKATAGA DISTRICT, MALASPINA DISTRICT 

ARCTIC COAST (ALASKA), QUEEN CHARLOTTE ISLANDS (BRITISH COLUMBIA)
PLATE 5

FIGURES 1, 6. Fortipecten mollerensis MacNeil, n. sp. (p. 43).

l.Holotype (USNM 645047), interior of left valve (same specimen as pi. 4, fig. 1), X 1. Unnamed formation (horizon probably upper Miocene or lower Pliocene), southeast of Point 

Divide, Herendeen Bay, Alaska Peninsula, USGS M2131. 

6. Paratype (USNM 645048), incomplete right valve, X 1. USGS M2131. 

2-4. Polynemamussium alaskense (Dall) (p. 6).

2. Figured specimen (USNM 644867), right valve, X 2. North side of Douglas Island, east 

of Entrance Point, USGS M243.

3. Figured specimen (USNM 644868), incomplete right valve, X 2. Glacier Highway, north 

shore of Auke Bay, USGS M218.

4. Figured specimen (USNM 644869), left valve, X 2. End of highway, north of Douglas

Island bridge, USGS M212. Postglacial deposits, Juneau area, southeastern Alaska. 

5. Delectopecten maddreni MacNeil, n. sp. (p. 5).

Holotype (USNM 644865), incomplete right valve and left valve, rubber cast, X 2. Burls 

Creek Shale Member of the Katalla Formation (horizon probably upper Oligocene), Burls 

Creek, Katalla district, Alaska, USGS 4321. 

7. Polynemamussium davidsoni (Dall) (p. 7).

Figured specimen (USNM 644870), left valve, X 2. North side of Douglas Island, east of 

Entrance Point, USGS M243. Postglacial deposits, Juneau area, southeastern Alaska.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 5

PECTINIDS FROM ALASKA PENINSULA, SOUTHEASTERN ALASKA, KATALLA DISTRICT (ALASKA)

223-848 O - 67 - 7
PLATE 6

[All figures X 1 unless otherwise noted]

FIGURES 1-3. Chlamysl nuwokensis MacNeil (p. 37).

Nuwok Formation of Ball (1919) (horizon probably upper Miocene), Carter Creek, Camden Bay region, northeastern Alaska, USGS D50 (T).

1. Holotype (USNM 561866), incomplete left valve, X IJi

2. Paratype (USNM 561867), incomplete left valve, X IJi

3. Paratype (USNM 561869), incomplete right valve, X 2. 

4, 5. Miyagipecten alaskensis MacNeil, n. sp. (p. 45).

Nunatuk north of east end of Pinnacle Hills, Malaspina district, Alaska. Upper part of 

Yakataga Formation (early Pliocene), USGS M1321.

4. Holotype (USNM 645049), incomplete right valve, rubber cast.

5. Paratype (USNM 645050), fragment of left valve showing sculpture, rubber cast, X V/z. 

6, 8, 10. Patinopecten (Lituyapecteri) n. sp. (p. 41).

Figured specimen.s Upper part of Yakataga Formation (horizon probably upper Miocene 

or lower Pliocene), Icy Point area, Lituya district, Alaska. This probably is the species 

figured as P. (L.) yakatagensis? (Clark) by MacNeil (1961, pi. 41, fig. 2).

6. Fragment of right valve (USNM 645044), USGS Ml 144.

8. Fragment of ?left valve (USNM 645045), USGS M1154.

10. Fragment of right valve (USNM 645046), USGS M1842. 

7. Patinopecten (Mizuhopecteri) skonunensis MacNeil, n. sp. (p. 42).

Hinge of holotype (pi. 4, fig. 2). UCLA loc. 4674. 

9. tChlamyssp. (p. 37).

Figured specimen (USNM 645030), fragment of ?left valve, X V/z. Unnamed formation 

(early? Miocene), Tanaga Island, Aleutian Islands, USGS D26 (T).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 6

PECTINIDS FROM ALEUTIAN ISLANDS, MALASPINA DISTRICT, LITUYA DISTRICT 

ARCTIC COAST (ALASKA), QUEEN CHARLOTTE ISLANDS (BRITISH COLUMBIA)
PLATE 7

[All figures X 1]

FIGURES 1-11. Chlamys (Leochlamys) tugidakensis MacNeil, n. sp. (p. 10).

Tugidak and Middleton Islands and the Lituya district, Alaska, all probably Pliocene.

Uppermost beds, Tugidak Island, USGS M1494:

1. Holotype (USNM 644871), a right valve.

2. Figured specimen (USNM 644873), anterior ear of a large left valve.

3. Paratype (USNM 643872), a left valve.

5. Figured specimen (USNM 644874), fragment of a left valve.

Middle beds, Tugidak Island, USGS M1895:

4, 6. Figured specimens (USNM 644875, 644876), dorsal fragments of left valves. 

7, 9. Figured specimens (USNM 644877, 644878), dorsal fragments of right valves. 

11. Figured specimen (USNM 644879), fragment.

Lower beds, Middleton Island, USGS M1753:

8. Figured specimen (USNM 644880), incomplete left valve.

Upper part of Yakataga Formation, La Perouse Glacier section, Lituya district, USGS M1851: 

10. Figured specimen (USNM 644881), fragment of ?right valve.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 7

PECTINIDS FROM TRINITY ISLANDS, MIDDLETON ISLAND, LITUYA DISTRICT (ALASKA)
PLATE 8

[All figures X 1 unless otherwise noted]

FIGURE 1. Chlamys (Leochlamys) tugidakensis MacNeil, n. sp. (p. 10).

Figured specimen (TJSNM 645052), an incomplete, partly decorticated large left valve. 

Lower beds (horizon probably upper Pliocene), Middleton Island, Alaska, USGS 

M1752. 

2-5, 7-9. Chlamys ("Chlamys") aff. C. ("C.") trinitiensis MacNeil (p. 21).

Figured specimens. Middle beds (Pliocene), Tugidak Island, Alaska, USGS M1895.

2. Incomplete right valve (USNM 644936).

3. Incomplete left valve (USNM 644937).

4. Incomplete right valve (USNM 644938).

5. Fragment of left valve (USNM 644939).

7. Fragment of left valve (USNM 644940).

8. Fragment of right valve (USNM 644941).

9. Fragment of right valve (USNM 644942). 

6, 10-12. Chlamys ("Chlamys") trinitiensis MacNeil, n. sp. (p. 20).

Upper beds (probably late Pliocene), Tugidak Island, Alaska, USGS M1494. 

6. Figured specimen (USNM 644934), an incomplete right valve.

10. Holotype (USNM 644933), right valve, X 1&

11. Figured specimen (USNM 644935), an incomplete left valve.

12. Holotype, left valve, X 1%.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 55S PLATE

10 11 12

PECTINIDS FROM TRINITY ISLANDS, MIDDLETON ISLAND (ALASKA)
PLATE 9

[All figures X 1 unless otherwise noted]

FIGUKES 1, 3-5. Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda (p. 29).

Figured specimens. Unnamed formation, upper part (horizon probably upper Pliocene),

Tugidak Island, Alaska, USGS M1494. 

1. Right valve (USNM 644983).

3. Left valve, same individual as above.

4. Left vavle (USNM 644984), X l>i

5. Right valve, same individual as above, X 1/4 

2, 6-10. Chlamys ("Chlamys") chaixensis MacNeil, n. sp. (p. 19).

Top of Chaix Hills section, upper part of the Yakataga Formation (horizon probably

upper Pliocene), Yakataga district, Alaska, USGS M1875. 

2. Figured specimen (USNM 644924), incomplete left valve.

6. Figured specimen (USNM 644925), incomplete right valve.

7. Figured specimen (USNM 644926), incomplete left valve.

8. Holotype (USNM 644921), right valve.

9. Figured specimen (USNM 644927), fragment of left valve. 

10. Holotype, left valve.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 9

PECTINIDS FROM TRINITY ISLANDS, YAKATAGA DISTRICT (ALASKA)
PLATE 10

[All figures X 1 unless otherwise noted]

FIGURES 1-3. Chlamys ("Chlamys") lioica (Ball) (p. 19).

Figured specimens. Top of Chaix Hills section, upper part of Yakataga Formation 

(horizon probably Pliocene), Yakataga district, Alaska, USGS M1875.

1. Incomplete right valve (USNM 644931).

2. Fragment of left valve (USNM 644932).

3. Right valve (USNM 644930). 

4, 5, 7, 8. Chlamys ("Chlamys1 '} chaixensis MacNeil, n. sp. (p. 19).

Top of Chaix Hills section, upper part of Yakataga Formation (horizon probably upper 

Pliocene), Yakataga district, Alaska, USGS M1875.

4. Paratype (USNM 644922), right valve of narrow ribbed variant.

5. Figured specimen (USNM 644928), right valve.

7. Figured specimen (USNM 644929), right valve.

8. Paratype (USNM 644923), right valve of a broad ribbed variant. 

6, 9-11. Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda (p. 29).

Figured specimens. Upper part of Yakataga Formation (horizon probably Pliocene),

Lituya district, Alaska. 

6. Incomplete right valve (USNM 644985), USGS M1969.

9. Incomplete left valve (USNM 644986), USGS D222 (T).

10. Incomplete right valve (USNM 644987), USGS D184 (T).

11. Left valve (USNM 644988), X 1& USGS D184 (T).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 10

PECTINIDS FROM YAKATAGA DISTRICT, LITUYA DISTRICT (ALASKA)
PLATE 11

[All figures X 1 unless otherwise noted]

FIGURES 1-3, 5, 6, 10. Chlamys (Chlamys) cf. C. (C.) picoensis chinkopensis Masuda and Sawada (p. 28).

Figured specimens. Unnamed formations on Tugidak and Middleton Islands 

(horizons probably upper Pliocene), Alaska.

1. Right valve (USNM 644977), upper beds, Tugidak Island, USGS M1494.

2. 3. Fragments of left valves (USNM 644978, 644979), lower beds, Middleton 

Island, USGS M1753.

5. Right valve (USNM 644980), USGS M1494.

6. Fragment of left valve (USNM 644981), USGS M1494. 

10. Right valve (USNM 644982), USGS M1494. 

4. Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda (p. 29).

Figured specimen (USNM 644989), fragment of right valve, X 2. Upper part 

of the Yakataga Formation (horizon probably Pliocene), Lituya district, Alaska, 

USGS D222. 

7, 8, 13. Chlamys (Chlamys) rubida prerubida MacNeil, n. subsp. (p. 23).

Unnamed formation, upper part (horizon probably upper Pliocene), Tugidak 

Island, Alaska, USGS M1494.

7. Paratype (USNM 644961), fragment of left valve.

8. Paratype (USNM 644962), fragment of left valve, X 1%. 

13. Holotype (USNM 644960), right valve, X 1%. 

9, 11, 12. Chlamys ("Chlamys") cf. C. ("C.") cosibensis (Yokoyama) (p. 17).

Figured specimens, X \%. Unnamed formation, upper part (horizon probably upper 

Pliocene), Tugidak Island, Alaska, USGS M1494.

9. Incomplete right valve (USNM 644906).

11. Incomplete left valve (USNM 644907).

12. Left valve (USNM 644905).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 11

13

PECTINIDS FROM TRINITY ISLANDS, MIDDLETON ISLAND, LITUYA DISTRICT (ALASKA)

223-848 O - 67 - 8
PLATE 12

[All figures X 1]

FIGURES 1, 2, 6, 7. Chlamys (Chlamys) pseudislandica plafkeri MacNeil, n. subsp. (p. 32).

Unnamed formation, upper beds (horizon probably lower Pleistocene), Middleton Island, 

Alaska.

1. Holotype (TJSNM 645002), right valve, USGS 17745.

2. Holotype, left valve, USGS 17745.

6. Figured specimen (USNM 645003), right valve, ?opposite valve of individual on 

pi. 12, fig. 7, USGS M1724.

7. Figured specimen (USNM 645004), left valve, USGS M1742. 

3, 5. Chlamys (Chlamys) cf. C. (C.) hanaishiensis amchitkana MacNeil (p. 30).

Figured specimens. Unnamed formation, upper beds (horizon probably Pleistocene),

Middleton Island, Alaska, USGS 17744. 

3. Incomplete right valve (USNM 644993), juvenile. 

5. Left valve (USNM 644994), juvenile. 

4. Chlamys ("Chlamys") cf. C. ("C.") coatsimiddletonensis. MacNeil, n. subsp. (p. 18).

Figured specimen (USNM 644920), incomplete left valve. Unnamed formation, upper 

beds (horizon probably lower Pleistocene), Middleton Island, Alaska, USGS 17745.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 12

PECTINIDS FROM MIDDLETON ISLAND (ALASKA)
PLATE 13

[All figures X 1]

FIGUKES 1, 2. Chlamys (Chlamys) pseudislandica plafkeri MacNeil, n. subsp. (p. 32).

Figured specimens. Unnamed formation, upper beds (horizon probably lower Pleistocene), 

Middleton Island, Alaska.

1. Incomplete right valve (USNM 645005), USGS M1743.

2. Left valve (USNM 645006), USGS M2054. 

3-5, 7. Chlamys ("Chlamys") coatsi middletonensis MacNeil, n. subsp. (p. 18).

Unnamed formation, upper beds (horizon probably lower Pleistocene), Middleton Island, 

Alaska, USGS M1741.

3. Holotype (USNM 644915), right valve.

4. Figured specimen (USNM 644916), incomplete right valve of fine ribbed variant.

5. Holotype, left valve.

7. Figured specimen (USNM 644917), incomplete right valve of coarse ribbed variant. 

6. Chlamys (Chlamys) islandica kanagae MacNeil, n. subsp. (p. 35).

Figured specimen (USNM 645013), incomplete right valve. Unnamed formation, upper

beds (horizon probably lower Pleistocene), Middleton Island, Alaska, USGS M1742. 

8. Chlamys (Chlamys) cf. C. (C.) hanaishiensis amchitkana MacNeil, n. subsp. (p. 30).

Figured specimen (USNM 644995), right valve, juvenile. Unnamed formation, upper 

beds (horizon probably lower Pleistocene), Middleton Island, Alaska, USGS M1744.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 13

PECTINIDS FROM MIDDLETON ISLAND (ALASKA)
PLATE 14

[All figures X 1]

FIGURES 1, 2, 4, 5. Chlamys (Chlamys) hanaishiensis amchitkana MacNeil, n. subsp. (p. 30).

Unnamed formations (horizons probably lower Pleistocene) on Middleton Island and 

Amchitka Island, Aleutian Islands, Alaska.

1. Figured specimen (USNM 644996), right valve. Middleton Island, upper beds, 

USGS 17743.

2. Figured specimen (USNM 644997), right valve. Middleton Island, upper beds, 

no locality data.

4. Holotype (USNM 644991), right valve. Amchitka Island, lower(?) beds, USGS 16908.

5. Para type (USNM 644992), fragment of left valve. Amchitka Island, lower (?) beds,

USGS 16908. 

3. Chlamys sp. (p. 36).

Figured specimen (USNM 645028), fragment of left valve, rubber cast. Unnamed formation, upper beds (horizon probably lower Pleistocene), Middleton Island, Alaska, 

USGS M1742. 

6, 7. Chlamys ("Chlamys"} coatsi MacNeil, n. sp. (p. 17).

Figured specimens. Unnamed formation, upper(?) beds (early or middle Pleistocene), 

Amchitka Island, Aleutian Islands, Alaska.

6. Left valve (USNM 644913), juvenile, USGS D46 (T).

7. Left valve (USNM 644914), juvenile, USGS 16908a. 

8. Chlamys ("Chlamys") coatsi middletonensis MacNeil, n. subsp. (p. 18).

Figured specimen (USNM 644918), left valve. Unnamed formation, upper(?) beds)

(early or middle Pleistocene), Amchitka Island, Aleutian Islands, Alaska, USGS D46

(T).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 14

PECTINIDS FROM ALEUTIAN ISLANDS, MIDDLETON ISLAND (ALASKA)
PLATE 15

[All figures X 1 unless otherwise noted]

FIGURES 1, 2, 5, 6. Chlamys ("Chlamys") coatsi MacNeil, n. sp. (p. 17).

Unnamed formation, upper (?) beds (early or middle Pleistocene), Amchitka Island, 

Aleutian Islands, Alaska.

1. Holotype (USNM 644908), left valve, USGS D46.

2. Figured specimen (USNM 644910), right valve, USGS D46.

5. Figured specimen (USNM 644911), right valve, slightly enlarged, USGS 16908a.

6. Paratype (USNM 644909), right valve, USGS 16908a.

3. Chlamys (Chlamys) islandica kanagae MaeNeil, n. subsp. (p. 35). 

Figured specimen (USNM 645014), fragment of left valve.

Unnamed formation (early or middle Pleistocene), Kanaga Island, Aleutian Islands, 

Alaska, USGS D3.

4. Chlamys (Chlamys) hanaishiensis amchitkana MacNeil, n. subsp. (p. 30).

Figured specimen (USNM 644998), right valve, juvenile. Unnamed formation, upper 

beds (early or middle Pleistocene), Amchitka Island, Aleutian Islands, Alaska, USGS 

16908a.

7. Chlamys ("Chlamys") coatsi MacNeil, n. sp. (p. 17).

Figured specimen (USNM 644912), left valve. Gubik Formation (horizon probably 

middle Pleistocene), mouth of Kuk River, near Wainwright, northern Alaska, USGS 

M1828.

8. Chlamys ("Chlamys") coatsi middletonensis MaeNeil, n. subsp. (p. 18).

Figured specimen (USNM 644919), right valve. Unnamed formation, upper (?) beds 

(early or middle Pleistocene), Amchitka Island, Aleutian Islands, Alaska, USGS D46.
PROFESSIONAL PAPER 553 PLATE 15

PECTINIDS FROM ALEUTIAN ISLANDS, ARCTIC COAST (ALASKA)
PLATE 16

[All figures X 1 unless otherwise noted]

FIGURES 1, 2, 4-7. Chlamys (Chlamys) islandica powersi MacNeil, n. subsp. (p. 35).

Unnamed formation, upper (?) beds (early or middle Pleistocene), Amchitka Island, 

Aleutian Islands, Alaska, USGS D46 (T).

1. Holotype (USNM 645022), right valve.

2. Figured specimen (USNM 645025), right valve.

4. Figures specimen (USNM 645026), right valve.

5. Figures specimen (USNM 645027), left valve.

6. Paratype (USNM 645023), left valve.

7. Paratype (USNM 645024), left valve. 

3. Chlamys (Chlamys) cf. C. (C.) rubida hindsii (Carpenter) (p. 23).

Figured specimen (USNM 637745), left valve, X l>i Recent, Douglas Island, near

Juneau, southeastern Alaska, USGS M213. 

8. Chlamys (Chlamys) cf. C. (C.) hanaishiensis Masuda (p. 29).

Figured specimen (USNM 644990), right valve, juvenile, X2}£. Unnamed formation, 

upper part (horizon probably upper Pliocene), Tugidak Island, Alaska, USGS M1494.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 16

PECTINIDS FROM ALEUTIAN ISLANDS, TRINITY ISLANDS, SOUTHEASTERN ALASKA (ALASKA)
PLATE 17

[All figures X 1]

FIGURES 1-4, 6-8. Chlamys (Chlamys) islandica kanagae MacNeil, n. subsp. (p. 35).

Unnamed formation (early or middle Pleistocene), Kanaga Island, Aleutian Islands, 

Alaska, TJSGS D3 (T).

1. Holotype (TJSNM 645011), right valve.

2. Figured specimen (USNM 645015), right valve.

3. Figured specimen (USNM 645016), fragment of left valve.

4. Figured specimen (USNM 645017), fragment of left valve.

6. Figured specimen (USNM 645018), incomplete right valve.

7. Figured specimen (USNM 645019), fragment of left valve.

8. Paratype (USNM 645012), left vlave. 

5. Chlamys (Chlamys) islandica kanagae MacNeil, n. subsp. (p. 35).

Figured specimen (USNM 645020), right valve. Unnamed formation (horizon probably 

lower Pleistocene), Adak Island, Aleutian Islands, Alaska, USGS 16907.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 17

223-848 O - 67 - 9

PECTINIDS FROM ALEUTIAN ISLANDS (ALASKA)
PLATE 18

[All figures X 1 unless otherwise noted]

FIGTJKE 1. Chlamys (Chlamys) islandica kanagae MacNeil, n. subsp. (p. 35).

Figured specimen (USNM 645021), incomplete right valve. Unnamed formation (early or 

middle Pleistocene), Kanaga Island, Aleutian Islands, Alaska, USGS D3.

2. Chlamys (Chlamys) islandica thulensis MacNeil, n. subsp. (p. 34).

Holotype (USNM 645010), incomplete left valve. Raised beach (probably postglacial), 

Narssurssuk, northwestern Greenland, USGS D386.

3. Chlamys (Chlamys) wainwrightensis MacNeil, n. sp. (p. 27).

Figured specimen (USNM 637754), right valve. Recent, Wainwright, northern Alaska,

USGS M2062. 

4, 6. Chlamys (Chlamys) rubida hindsii (Carpenter) (p. 23).

Postglacial deposits, Juneau area, southeastern Alaska.

4. Figured specimen (USNM 644948), left valve, Glacier Highway, north shore of Auke Bay,

USGS M218. 

6. Figured specimen (USNM 644947), right valve, X \%, north side of Douglas Island, east

of Entrance Point, USGS M243. 

5. Chlamys (Chlamys) beringiana colvillensis MacNeil, n. subsp. (p. 26).

Holotype (USNM 561912), incomplete right valve. Gubik Formation, lower part (horizon 

probably lower Pleistocene), Colville River at Ocean Point, northern Alaska, USGS D306.

7. Chlamys (Chlamys) cf. C. (C.) beringiana colvillensis MacNeil (p. 26).

Figured specimen (USNM 644968), fragment of left valve, Submarine Beach (late Pliocene or early Pleistocene), Nome, Alaska, USGS M1256.

8. Chlamys (Chlamys) islandica islandica Muller) (p. 33).

Figured specimen (USNM 645007), left valve. Raised terrace deposit (postglacial; radiocarbon dated at 10,200 yrs B.P.), Reykjavik Airport, Iceland, USGS M2055.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553, PLATE 18

PECTINIDS FROM ALEUTIAN ISLANDS, SOUTHEASTERN ALASKA, SEWARD PENINSULA 

ARCTIC COAST (ALASKA), GREENLAND, ICELAND
PLATE 19

[All figures X 1]

FIGURES 1, 3, 4, 6. Chlamys (Chlamys) rubida hindsii (Carpenter) (p. 23).

Figured specimens. Postglacial deposits, Juneau area, southeastern Alaska. 

1. Right valve (USNM 644949), south of Fish Creek on road north of bridge, Douglas 

Island, USGS M214.

3. Left valve (USNM 644950), USGS M214.

4. Left valve (USNM 644951), USGS M214.

6. Left valve (USNM 644952), north side of Douglas Island east of Entrance Point,

USGS M243. 

2, 5. Chlamys (Chlamys) islandica islandica (Mtiller) (p. 33).

Figured specimens. Raised terrace deposits (postglacial; radiocarbon dated at 10,200

yrs B.P.), Reykjavik Airport, Iceland, USGS M2055. 

2. Left valve (USNM 645008). 

5. Right valve (USNM 645009). 

7. Chlamys (Chlamys) pseudislandica MacNeil, n. sp. (p. 31).

Figured specimen (USNM 637759), right valve. Recent, St. Lawrence Island, northern

Bering Sea, USGS D373.

8, 9. Chlamys (Chlamys) wainwrightensis MacNeil, n. sp. (p. 27). 

Recent, northern Alaska.

8. Figured specimen (USNM 637755), a right valve, Wainwright, USGS M2056.

9. Holotype (USNM 637756), a left valve, Point Hope, USGS M1339.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 19

PECTINIDS FROM SOUTHEASTERN ALASKA, ST. LAWRENCE ISLAND 

ARCTIC COAST (ALASKA), ICELAND
PLATE 20

[All figures X 1 unless otherwise noted]

FIGURES 1, 3, 4. Chlamys (Chlamys} beringiana unalaskae MacNeil, n. subsp. (p. 27). 

Recent, Unalaska Island, Aleutian Islands, Alaska, USGS D53. 

1. Holotype (USNM 637751), right valve, X \%.

3. Paratype (USNM 637752), left valve, X \%.

4. Paratype (USNM 637753), left valve, X \%. 

2. Chlamys (Chlamys) beringiana (Middendorff) subsp. ?(p. 24).

Figured specimen (USNM 637746), left valve. Recent, Point Hope, northwestern Alaska,

USGS M1339. 

5, 6. Chlamys (Chlamys) rubida hindsii (Carpenter) (p. 23).

Figured specimens. Recent, Excursion Inlet, southeastern Alaska, USGS M223.

5. Left valve (USNM 637741).

6. Right valve (USNM 637742). 

7, 9. Chlamys (Chlamys) rubida (Hinds) (p. 21).

Figured specimen (USNM 150220), both valves of same individual. Recent, Alaska 

Peninsula.

7. Left valve. 

9. Right valve. 

8. Chlamys (Chlamys) pseudislandica MacNeil, n. sp. (p. 31).

Figured specimen (USNM 637760), left valve. Recent, Wainwright, northern Alaska, 

USGS M2056.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 20

PECTINIDS FROM ALEUTIAN ISLANDS, ALASKA PENINSULA, ARCTIC COAST 

SOUTHEASTERN ALASKA (ALASKA)
PLATE 21

[All figures X 1]

FIGURES 1, 3. Chlamys ("Chlamys") hastata hericius (Gould) (p. 14).

Figured specimen (GAS 12611), both valves of the same individual. Recent, Puget Sound,

Washington, GAS loc. 31879.

2, 5-7. Chlamys (Chlamys) beringiana (Middendorff) (p. 24). 

Figured specimens. Recent. 

2. Incomplete right valve (USNM 637747), St. Paul Island, Pribiloff Islands, USGS M1622

5. Incomplete left valve (USNM 637748), St. Paul Island, Pribiloff Islands, USGS M1621.

6. Incomplete left valve (USNM 637749), St. Lawrence Island, northern Bering Sea, USGS 

D373.

7. Right valve (GAS 12746), St. Paul Island, Pribiloff Islands, GAS loc. 18493. 

4. Chlamys (Chlamys) rubida hindsii (Carpenter) (p. 23).

Figured specimen (USNM 637743), a left valve of the variant with sharp-topped ribs. Recent, Excursion Inlet, north side of Icy Strait, southeastern Alaska, USGS M234. 

8, 9. Chlamys (Chlamys) islandica erythrocomata (Dall) (p. 36).

Holotype (USNM 110462), both valves. Recent, Albatross sta. 5021, Okhotsk Sea, depth 

73 fathoms. This is the first published illustration of the holotype.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 21

PECTINIDS PROM PUGET SOUND (WASHINGTON), SOUTHEASTERN ALASKA 

PRIBILOF ISLANDS (ALASKA), OKHOTSK SEA
PLATE 22

[All figures X 1 unless otherwise rioted]

FIGURES 1, 2. Chlamys (Chlamys) rubida hindsii (Carpenter) var.? (p. 23).

Figured specimens. Postglacial deposits, Juneau area, southeastern Alaska.

1. Incomplete large right valve (TJSNM 644956), south of Fish Creek on road north of bridge, 

Douglas Island, USGS M214.

2. Right valve (USNM 644957), mouth of Eagle River on Lynn Canal, USGS 5461. 

3. Chlamys (Chlamys) rubida jordani (Arnold) (p. 22).

Figured specimen (USNM 644945), right valve. Fernando Formation (horizon uppermost 

Pliocene), about \% mile south of northeast end of Orange County Airport and near head 

of Newport Bay, Orange County, Calif., USGS M2130. 

4, 5. Chlamys ("Chlamys") pugetensis (Oldroyd) (p. 15).

Figured specimens. Recent, Sitkalidak Island, east side of Kodiak Island, Alaska, USGS 

M2064.

4. Right valve (USNM 637739), X 2.

5. Left valve (USNM 637740), X 2. 

6. Chlamys (Chlamys) hanaishiensis amchitkana MacNeil, n. subsp. (p. 30).

Figured specimen (USNM 644999), incomplete right valve. Unnamed formation, lower (?) 

beds (horizon probable lower Pleistocene), Amchitka Island, Aleutian Islands, Alaska, 

USGS 16908. 

7, 8. Chlamys (Chlamys) cf. C. (C.) rubida (Hinds) (p. 21).

Figured specimens. Postglacial deposits, Juneau area, Alaska, end of highway north of 

Douglas Island bridge, USGS M212.

7. Right valve (USNM 644943).

8. Fragment of a left valve (USNM 644944).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 22

PECTINIDS FROM ALEUTIAN ISLANDS, SITKALIDAK ISLAND OFF KODIAK 

SOUTHEASTERN ALASKA (ALASKA), CALIFORNIA
PLATE 23

[All figures X 1 unless otherwise noted]

FIGURES 1, 2. Chlamys (Chlamys) pseudislandica MacNeil, n. sp. (p. 31).

Holotype (CAS 12612), both valves. Recent, 5 miles off Point Marsh, near Wainwright, 

Arctic coast of Alaska, CAS loc. 34358.

3. 6. Chlamys (Chlamys) beringiana (Middendorff) (p. 24). 

Figured specimens. Recent, Arctic coast of Alaska. 

3. Right valve (CAS 12614), 2 miles off Arcon Camp, Point Barrow, northern Alaska, CAS

loc. 34333. 

6. Left value (CAS 12613), 3/l 2 miles off Wainwright, Artic coast of Alaska, CSA loc. 34337.

4. 5. Chlamys (Chlamys) wainwrightensis MacNeil, n. sp. (p. 27). 

Recent, northern Alaska.

4. Paratype (USNM 637757), a right valve, Point Hope, USGS M1339.

5. Figured specimen (USNM 637758), a left valve, X 1& Wainwright, USGS D318. 

7, 8. Chlamys (Chlamys) pseudislandica arconis MacNeil, n. subsp. (p. 33).

Figured specimen (CAS 12747), both valves. Recent, 17 miles west of Arcon Beach, near 

Point Barrow, northern Alaska, CAS loc. 34347.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 23

PECTINIDS FROM ARCTIC COAST (ALASKA)

223-848 O - 67 - 10
PLATE 24

FIGURE 1. Chlamys (Chlayms) rubida hindsii (Carpenter) (p. 23).

The specimen figured by Middendorff (1849, pi. 12, fig. 9) as Pecten rubidus Hinds?. Probably from Sitka, Alaska. Recent. In Zoological Institute, Leningrad.

2. Chlamys (Chlamys) beringiana (Middendorff) (p. 24).

Lectotype. The largest of three specimens figured by Middendorff (1849, pi. 13, fig. 1) as 

Pecten islandicus var. behringiana. Probably from Bering Sea. Recent. In Zoological 

Institute, Leningrad.

3. Chlamys (Chlamys) beringiana (Middendorff) (p. 24).

Figured specimen (USNM 637750), an incomplete right valve. Recent, St. Lawrence

Island, northern Bering Sea, TJSGS D373. 

4,6. Chlamys ("Chalmys") harmeri Altena (p. 15).

Figured specimens. Probably Scaldesian (early Pleistocene). Dredged from the Westerschelde, western Netherlands, USGS M2519. 

4. Right valve (USNM 644895).

6. Left valve (USNM 644896). 

5. Chlamys (Chlamys) rubida jordani (Arnold) (p. 22).

Figured specimen (USNM 644946), X 1^2- Santa Barbara Formation (horizon upper

Plicoene), Santa Barbara County, Calif., USGS M1918. 

7, 10. Chlamys ("Chlamys") hastata (Sowerby) (p. 14).

Figured specimens. Santa Barbara Formation (horizon uppermost Pliocene), Santa 

Barbara County, Calif., USGS M1717.

7. Right valve (USNM 644891). 

10. Left valve (USNM 644892), X 1A- 1

8, 9. Chlamys (Chlamys) rubida hindsii (Carpenter) (p. 23).

Figured specimen (USNM 637744). Recent, Excursion Inlet, southeastern Alaska, USGS 

M234.

8. Left valve, coated with ammonium chloride.

9. Same specimen, uncoated to show color markings. 

11. Chlamys (Chlamys) picoensis kinoshitai Kubota (p. 29).

Holotype (in collections of Hokkaido Fish Experiment Station), right valve. Recent,

Araito Island, northern Kurile Islands. 

12, 13. Chlamys (Chlamys) islandica (Miiller) subsp.? (p. 34).

Figured specimens. Recent, Tjornes, northern Iceland, USGS M2464.

12. Right valve (USNM 637761).

13. Left valve (USNM 637762).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 24

PECTINIDS FROM ST. LAWRENCE ISLAND, SOUTHEASTERN ALASKA (ALASKA),? BERING SEA 

CALIFORNIA, KURILE ISLANDS, ICELAND, NETHERLANDS
PLATE 25

[All figures X 1]

FIGURES 1-3. Chlamys ("Chlamys") tjornesensis MacNeil, n. sp. (p. 16). 

Tjornes beds near Hallbjarnarstadhaa, northern Iceland.

1. Figured specimen (USNM 644904), incomplete left valve, rubber cast. Serripes groenlandicus zone (early Pleistocene), USGS M2155.

2. Para type (USNM 644903), incomplete left valve. Upper part of Mactra zone (late 

Pliocene), USGS M2203.

3. Holotype (USNM 644902), incomplete right valve. Upper part of Mactra zone (late

Pliocene), USGS M2203. 

4-8. Chlamys ("Chlamys") breidavikensis MacNeil, n. sp. (p. 16).

Tjornes beds near Breidhavik, northern Iceland. Base of highest bed in Breidhavik section, 

USGS M2153.

4. Paratype (USNM 644898), incomplete left valve, rubber cast.

5. Figured specimen (USNM 644899), incomplete right valve.

6. Holotype (USNM 644897), incomplete right valve, rubber cast.

7. Figured specimen (USNM 644900), incomplete left valve, rubber cast.

8. Figured specimen (USNM 644901), incomplete right valve, rubber cast.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 553 PLATE 25

PECTINIDS FROM ICELAND