Upper Silurian 

Brachiopods from 

Southeastern Alaska

GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-C
Erratum 

Plate 8; title. Delete Carchidium,
Upper Silurian

Southeastern Alaska

By EDWIN KIRK and THOMAS W. AMSDEN

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952, PAGES 53-66

GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-C

Descriptions and illustrations of a fauna 

from the Islands of Kosciusko and Heceta

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1952
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

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

Washington 25, D. C. - Price 55 cents (paper cover)
CONTENTS

Page 

Abstract_ ___________________________________________________________________________________________________ 53

Introduction._________________________________________________________________________________________________ 53

Systematic descriptions_______________________________________________________________________________________ 55

References____-_--_-___---_____-___________________________-__________________________________________________ 64

Index._______________________________________________________________________________________________________ 65

ILLUSTRATIONS

Page 

PLATE 7. Atrypella, Lissatrypa, Nucleospira, Alaskospira, Howellella, and Delthyris. ________________________Following index

8. Camarotoechia, Atrypa, Atrypella, and Conchidium______________________________________________Following index

9. Conchidium alaskense.. ____________________________________________________________________Following index

10. Conchidium, Camarotoechia, Eospirifer, Howellella, and C?/mos£ropfo'a-____________-_______-_-_---_-Following index

FIGURE 2. Serial sections of Camarotoechia reesidei, n. sp------_-_-_-____-----___-_____--____--_-__--__-_----_---__ 57

3. Serial section of Atrypella scheii (Holtdahl)____________________________________________-__--____--_____ 58

4. Serial sections of Lissatrypa atheroidea Twenhofel_____________________________________________________ 59

5. Serial sections of Atrypella tennis, n. sp____________________________.___________________-_---_---_-_- 60

6. Serial sections of Atrypella borealis, n. sp_-___-__-___--___________-___-__-_____-___-____---_-__---____- 60

7. Serial sections of Alaskospira dunbari, n. sp_-----__--_--___--_----_----------------.___----_-------_-__- 62

ill

UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA

By EDWIN KIRK AND THOMAS W. AMSDEN

ABSTRACT

The present paper adds to the yet meager knowledge of the 

Upper Silurian brachiopod fauna of Alaska.

Of the 21 species of Upper Silurian brachiopods herein considered, 6 are new, 6 were described in earlier publications by 

Kirk, 3 are referred to species of Barrande, Holtedahl, and 

Linnaeus, and 6 are neither referable to known species nor 

sufficiently well understood to be described as new. One new 

genus, Alaskospira, is described.

Although much remains to be done with the fauna in question, 

it is considered desirable to make the present information available and to call attention to resemblances between this fauna 

and one from the Upper Silurian of the eastern Urals.

INTRODUCTION

The Silurian fossils herein described were, for the most 

part, collected by Kirk in 1917 on Kosciusko and Heceta 

Islands, off the west coast of Prince of Wales Island 

about 100 miles north of the Alaska-British Columbia 

line. In earlier papers by Kirk (1922, 1925, 1926), the 

brachiopod genera Brooksina, Harpidium, and Cymbidium were first described. The present report supplements these earlier works by making known additional 

elements of the important upper Silurian brachiopod 

fauna of Alaska. Although it still leaves much of the 

fauna undescribed, it is considered desirable, because of 

current interest in the Silurian stratigraphy of Alaska, to 

make generally available 1 at one source, descriptions of 

some of the commoner and more important species and 

genera.

Very little has been published about the stratigraphy 

of Kosciusko and Heceta islands, or of the general region 

in which they are situated. A report by Buddington 

and Chapin on the Geology and Mineral Resources of 

Southeastern Alaska (1922) contains a brief description 

of the Silurian stratigraphy of this area, but their work 

was, of necessity, largely reconnaissance and does not 

give much information about the faunal sequence. For 

this reason, and because the fauna is not known elsewhere in North America, the exact stratigraphic position 

of the beds that yielded present collections is uncertain. 

It is hoped that further stratigraphic and paleontologic 

work will reveal the proper relationship of these strata 

to beds bearing known North American faunal assemblages, so the fauna described can be fitted into the 

general faunal sequence.

» Khodalovich (1939) has published, in Russian but with a good English summary, 

descriptions of a very similar fauna from the eastern slope of the Urals, but copies of 

this publication are not generally available in North America.

Ill addition to the 6 species described earlier by Kirk, 

15 are treated in the present paper. These 15 species, of 

which 6 are new, are referred to 12 genera, of which one 

is new. The known geographic distribution of the 21 

species is tabulated below.

U. S. Geological Survey locality numbers

Conchidium alaskense Kirk and AmsAlaskospira dunbari Kirk and AmsNudeospira hecetensis Kirk and AmsCamarotoechia reesidei Kirk and AmsIsorthis sp

Cymostrophia cf. C. costulata (Barrande). _______ . ____ .. __

1005

X

X

X

X

X

v

X

X

X

987

X

X

X

984

X

1019

X

1589

X

983 2689

X

X

X

X

X

X

X

X

X

X

Localities in southeastern Alaska from which collections were

obtained

Locality 1005. Vermont marble prospect, south shore of Kosciusko

Island, between Edna Bay and Holbrook; Kirk 1917. 

Locality 987. "Marble Bay." north shore of Heceta Island; Kirk

1917. (Probably the same stratigraphic zone as locality 1005). 

Locality 984. South shore of Kosciusko Island, between Edna Bay

and Holbrook; Kirk 1917. This is near locality 1005, but from

a stratigraphically higher zone. 

Locality'1019. Limestone overlying tillite; "Blue Bluff", east end

of Heceta Island, north of high cliffs; Kirk 1917. 

Locality 1589. East end of Heceta Island; Girty and Waters, 1917. 

Locality 983. Limestone above tillite; west shore of "Marble

Cove," north shore of Heceta Island; Kirk 1917. 

Locality 2689. Northeast end of Heceta Island, northern tip of a

small peninsula just across the channel from Tuxekan Island;

Eberlein 1947.

As shown in the table, most of the species came from localities 

1005 and 2689. These species are represented in collection 987 

and only one from each of the others. Only Brooksina alaskensis 

Kirk, Harpidium insignis Kirk, Atrypella scheii (Holtedahl)? 

and Atrypa cf. A. reticularis (Linnaeus) are present in collections 

from two or more localities. As the stratigraphic relationships 

of the localities are uncertain, and as little is known about the 

geology of these islands, it seems best to consider the ages and 

possible correlations of the various localities separately, rather 

than to consider the fauna as a whole.

53
54 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

One of the largest and best-preserved faunas comes 

from locality 1005, on the south shore of Kosciusko 

Island, which has yielded 9 species, 4 belonging to the 

pentameroid genera Brooksina, Harpidium and Cymbidium. Locality 987 probably represents a similar zone 

on Heceta Island. In earlier papers (Kirk, 1922, 1925, 

1926) it was concluded that these genera were probably 

to be referred to the upper Silurian. As was pointed out, 

however, these brachiopods do not appear to have any 

close relationship with those known from North 

America 2 but seem to have their closest affinities with 

the upper Silurian faunas of Asia.

The additional brachiopods described in the present 

work from locality 1005 seem further to substantiate 

these conclusions. The genus Atrypella is not common 

in North America; Cooper has described A. shrocki from 

the Niagaran of Indiana but this species is quite distinct 

from A. tennis, A. borealis, and A. scheii (Holtedahl)? 

from localities 1019, 1589, and 2689. Alaskospira dunbari represents a new genus and species which is known 

only from locality 1005 on Kosciusko. The only other 

forms which we record from this locality are Atrypa cf. 

A. reticularis (Linnaeus) and Delthyrisl sp., but these as 

herein identified can have little diagnostic value.

The genus Conchidium is well represented in other 

North American Silurian faunas, but our species, C. 

alaskense from locality 983 most closely resembles C. 

knighti (Sowerby) from the Aymestry limestone (Ludlovian) of England. It is also somewhat similar to the 

large C. vogulicum (Verneuil; see Tschernyschew 1893, 

pi. 11, figs. la-Id) from the lower Devonian(?) of the 

Urals.

The fauna of locality 2689 at the northeast end of 

Heceta Island consists of the following:

Atrypella scheii (Holtedahl)?

Atrypa cf. A. reticularis (Linnaeus)

Nucleospira hecetensis n. sp.

Camarotoechia reesidei n. sp.

Camarotoechia sp.

Isorthis sp.

Gypidulal sp.

Eospirifer sp.

Howellella sp.

Cymostrophia cf. C. costulata (Barrande)

It is rather difficult to compare this fauna with others 

because the poor preservation makes accurate specific 

identification impossible in most cases. The species of 

Atrypella herein described is probably conspecific with 

Holtedahl's species from Ellesmereland and similar 

Atrypellas have been recorded from Asiatic faunas. 

The Cymostrophia from Heceta is much like C. costulata 

(Barrande) from Bohemia, but Nucleospira hecetensis, 

and Camarotoechia reesidei are both new species and 

hence of little value in age determination. The rest of 

the fauna has not been identified as to species. It is

1 Excluding Greenland and Ellesmereland which are discussed separately; these 

three genera have not been recorded from other areas on this continent with the 

possible exception of Brooksina which G. A. Cooper (1944, p. 305) reported from 

western Tennessee.

not possible to draw definite conclusions concerning the 

age of such a poorly known fauna, but the presence of 

Atrypella scheiif suggests that the affinities were closer 

to late Silurian faunas of Arctic and Asiatic areas than 

to North American faunas.

In 1914 Holtedahl described a fauna from southwestern Ellesmereland to which he assigned a Ludlovian age. 

The brachiopods in this assemblage appear to have some 

similarities with those from southeastern Alaska. 

Holtedahl's species Atrypella scheii is very probably the 

one present in collections from localities 1019, 1589, and 

2689; he also described a new species of Conchidium 

(C. arcticum), but this is considerably smaller and more 

finely ribbed than C. alaskense from locality 983. 

Cymostrophia patersoni var. antigua (Holtedahl) is 

similar to the Cymostrophia from locality 2689, although 

the concentric corrugations appear to be better developed on the Ellesmereland species. In addition, Holtedahl recorded Gypidula coeymanensis var. prognostica 

Schuchert, Camarotoechia litchfieldensis var. prognostica 

(Schuchert); these genera are present in collection 2689, 

although the species are different. He has also recorded species of several genera that are not present in 

the collections discussed in the present reports. These 

are: Strophonella cf. S. euglypha Hall, Schuchertella 

interstriata var. sinuata Holtedahl, Stenoschisma deckerensis var. arctica (Holtedahl), and Spirifer modestus var. 

striatissimus Holtedahl.

Poulsen (1943) has described a fairly large fauna of 

brachiopods from northern Greenland. These specimens came from the Offley Island formation, which, 

Poulsen states is "Upper Llandovery (Middle Clinton)" 

in age. This fauna carries six species of Harpidium 

including H. insignis Kirk. He also records Eospirifer 

radiatus (Sowerby), but this is not like the Eospirifer 

shown on plate 10, figure 6, from locality 2689. The 

remainder of the Offley Island brachiopods do not 

appear to have much in common with those from 

southeastern Alaska.

Probably the Alaska upper Silurian brachiopod fauna 

most closely resembles one described by Khodalevich 

(1939) from the eastern slope of the Urals. The strata 

from which he obtained his specimens was assigned to 

the Upper Wenlock and Lower Ludlovian on the basis 

of a faunal study which embraced not only brachiopods, 

but also corals, gastropods, pelecypods and cephalopods 

(1939, p. 112). The generic suite seems to be similar 

to that of the present report, and there are also some 

specific similarities.

Some features of Khodalevich's paper warrant special 

notice. He described a large number of pentameroid 

brachiopods, referring most of them to the genus Conchidium and one of them, C. vogulicum var. krutolowskiensis Kodalevich, is somewhat like our species 

C. alaskense from locality 983. He also recognized 

three species of Brooksina, B. conjugula Khodalevich, 

B. striata (Eichwald), 5.(?) crassa Khodalevich. The
UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA

form described as Pentamerus magnus Khodalevich is 

possibly a species of Harpidium. Illustrations of the 

species he referred to the genus Lissatrypa strongly 

suggest the genus Atrypella. Lissatrypa penitus 

Khodalevich and L. penitus var. elongata Khodalevich 

are similar in their external features to Atrypella scheii 

(Holtedahl) and were compared by Khodalevich with 

Holtedahl's species. Khodalevich illustrates several 

species of Eospirifer of which E. irbitensis (Tschernyshew) has some resemblance to the one which we 

illustrate on plate 10, figure 6. The species identified 

by Khodalevich as Cymostrophia costulata (Barrande) 

has an outline and ornamentation suggesting the 

Cymostrophia figured on plate 10, figure 12, of the 

present report. Another possible point of similarity 

between the Alaskan fauna and that of the Urals is 

the presence of a species described by Khodalevich as 

Spirifer (Martinial} pseudopentameriformis and which 

may be a representative of the genus herein described 

as Alaskospira.

Thus there appears to be some basis for considering 

the brachiopods from the eastern slope of the Ural 

Mountains closely contemporaneous with those from 

southeastern Alaska. A comparison of the other 

faunal elements may help further to substantiate this 

correlation.

In summary, this Alaskan brachiopod fauna does 

not appear to have any close relationship with other 

known North American faunas. Its closest affinities 

seem to be with the upper Silurian faunas of Asia and 

of Europe. Until the Asiatic faunas have been described in greater detail, and until the faunal sequences 

in Asia and Alaska have been more fully studied, it 

will not be possible to establish detailed correlations.

SYSTEMATIC DESCRIPTIONS

SUPERFAMILY DALMANELLACEA

Genus Isorthis Kozlowski, 1929

Isorthis sp.

There is a specimen of a punctate, subequally biconvex shell with moderately fine costellae which is 

provisionally placed in the genus Isorthis. The interior of the pedicle valve shows dental lamellae, but 

none of the other characters can be determined.

A single specimen from locality 2689, northeast 

corner of Heceta Island, southeastern Alaska.

SUPERFAMILY STROPHOMENACEA

Genus Cymostrophia Caster, 1939 

Cymostrophia cf. C. costulata (Barrande)

Plate 10, figures 12-13 

Strophomena costulata Barrande (1879, pi. 48, figs. 3, 1-13).

We have two incomplete specimens that are similar 

to C. costulata (Barrande) from Etage E in Bohemia.

The brachial valve of our specimens is moderately 

concave and the pedicle valve is moderately convex. 

About half of the denticulate cardinal margin is preserved on the most complete specimen. The costellae 

are in groups of two or three smaller ones alternating 

with a single, heavier rib. The large ribs are not 

uniform through their length, but are alternately 

pinched and swollen, extending forward a few millimeters as strong ribs and then becoming faint for a 

short distance before enlarging again (pi. 10, fig. 13). 

In addition, the surface shows faint, irregular, concentric corrugations, although these are not as well 

developed as in other species of this genus.

Two specimens from locality 2689, northeast end of 

Heceta Island, southeastern Alaska, U.S.N.M. 116554, 

116555.

SUPERFAMILY PENTAMERACEA

Genus Conchidium Oehlert 

Conchidium alaskense Kirk and Amsden, n. sp.

Plate 8, figures 23-29; plate 9, figures 1-7; 

plate 10, figures 1, 5,10, 11, 14

The lateral profile of shells belonging to this species 

is highly varied, although they are invariably strongly 

biconvex at maturity. Very young specimens have a 

pedicle beak which is small, suberect and only slightly 

hooked over the brachial valve. As the shell increases 

in size, the beak becomes more prominent and tends to 

be curved in a brachial direction, but its profile differs 

considerably between individuals. On some specimens 

it is sharply curved over the other valve as shown on 

plate 8, figure 24 (on no specimens does it come in 

actual contact with the brachial valve); on other shells 

it is more erect, being only slightly inclined in a brachial 

direction (pi. 9, fig. 4). Within the collections are 

specimens showing all gradations between these two 

types.

The outline of these shells is also varied, but in all 

specimens the maximum width is attained near the 

anterior end, making the shell somewhat subtriangular. 

The differences in outline are due primarily to variations 

in the ratio of width to length; this ratio ranges from 

a specimen in which the length is about equal to the 

width (86 mm. long. 81 mm. wide) to one in which the 

length greatly exceeds the width (82 mm. long, 55 mm. 

wide).

Many of the specimens show a definite asymmetrical 

growth, and are longer on one side of the median plane. 

These growth irregularities reach maximum development in shells such as that shown in plate 8, figures 26 

and 28, where the shell is twisted throughout its length. 

Such irregularities may be due to the fact that these 

animals lived in great abundance upon the sea floor 

and were crowded upon one another during growth.

»The status of the generic name Conchtdium is uncertain (St. Joseph 1937, pp. 

258-265; Alexander 1948, pp. 145). Alexander (1951, pp. 89-94) has recently submitte d 

a proposal to the International Commission on Zoological Nomenclature to have 

Conchidium Oehlert 1887 added to the Official List of Generic Names in Zoology.
56 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

Both valves bear coarse costae which become obsolete and disappear toward the lateral margins. The 

costae are subangular and separated by V-shaped interspaces. The anterior margin of a specimen of average 

size bears 9 to 14 costae in a space of 40 mm. The 

shell shown on plate 8, figure 27, has unusually coarse 

ribs, with 7 in 40 mm.; the largest specimen in the 

collection (pi. 10, figs. 1, 5, 10) also bears 7 costae in 

40 mm.

The collections under study include a large number 

of specimens, representing almost all growth stages 

from less than 20 mm. in length to about 120 mm. in 

length. This series shows that growth took place in 

the following manner: Commonly the youngest individuals are subtriangular in outline (pi. 8, fig. 23) and 

weakly biconvex, with the pedicle valve only slightly 

deeper than the brachial. As the shell increased in 

size the pedicle valve increased in depth more rapidly 

than the brachial. This resulted primarily from accelerated growth of the lateral margins, in a zone extending 

roughly from the delthyrium to the anterior edge. 

The material deposited in this zone is not costate, but 

shows only faint growth lines parallel to the lateral 

edge. By the time the animal was fairly well grown 

it was strongly biconvex, with the pedicle valve about 

twice as deep as the brachial. The following measurements are taken from a suite of individuals selected to 

show different growth stages. Such a selected group 

does not, of course, show all of the variations present 

in the species.

Dimensions in millimeters

Length 

19 

26 

34 

44 

60 

72 

81 

78 

122

Width

22

30

36

49

63

57

82

66 

116

Thickness 

12 

16 

20 

38 

50 

65 

68 

70 

88

The internal structures of Conchidium alaskense 

agree with the generic diagnosis given by Schuchert 

and Cooper (1932, p. 181). The pedicle interior 

possesses a spondylium duplex which is extremely long, 

narrow and deep. As shown in figure 7 of plate 9 this 

structure is much extended in an antero-dorsal direction, coming to within a few millimeters of the floor 

of the brachial valve; this spondylium is supported by 

a high median septum for about two-thirds of its length. 

In this respect our specimens differ from the generic 

diagnosis given by Alexander (1948, p. 149) "spondylium fully supported on a high duplex septum."

The septal plates in the brachial valve are clearly 

divisible into three parts: the inner and outer plates 

separated by a flexure and slight thickening (pi. 9, 

fig. 7). This thickened portion extends beyond the 

outer and inner plates as brachial supports.

Conchidium alaskense is most similar to C. knighti 

from the Aymestry limestone of England (Sowerby 

1813, pp. 73-74, pi. 28, top figure; the type of this 

species has been redescribed by Alexander 1948, pp. 

150-153, pi. 7, fig. 1-3). Both species have a large 

shell, the Alaskan specimens reaching a length of 122 

mm. and those from England as much as 173 mm. 

Also, both have rather coarse ribbing, although that of 

C. knighti may be a little the finer.

There are some differences between C. knighti and 

the specimens under consideration, however, which 

clearly warrant establishing the new species C. alaskense. 

Internally, the spondylium of C. knighti is fully supported by the median septum as is brought out in 

Alexander's description and illustration and also in 

Davidson's illustrations of this species (Hall and Clarke 

1894, pi. 64, figs. 14-16, reproduced three of Davidson's 

illustrations of C. knighti from the Aymestry limestone). 

Several specimens of C. alaskense show the interiors 

clearly and in none of these does the median septum 

extend to the end of the spondylium. The anterior 

end of the spondylium hangs free as shown in figure 7 

of plate 10.

There are also external differences between C. 

alaskense and C. knighti. Commonly, the pedicle valve 

of C. alaskense is curved over the brachial valve, but 

apparently not as strongly so as hi Sowerby's species. 

According to Alexander there is a strong incurving of 

the pedicle umbo in C. knighti, which hi gerontic individuals leads to an inrolling of the pedicle beak until it is 

so tightly pressed against the opposite valve that the 

shell cannot be opened. None of the specimens of 

C. alaskense show the pedicle beak hi conjunction with 

the brachial. C. knighti appears to have a more 

rounded shell outline with the maximum width attained 

some distance back from the anterior margin. Although the shape of C. alaskense varies greatly, the 

maximum width is commonly attained near the anterior 

end, thus producing a subtriangular shape.

Conchidium alaskense resembles C. vogulicum (Verneuil; Tschernyschew, 1893, p. 182, pi. 11, figs. la-Id) 

from the Lower Devonian (?) of the Urals. C. vogulicum has a very large shell, even larger than that of C. 

alaskense or C. knighti, but it does not have the triangular outline of our species and its ribbing is much 

finer. Also, Tschernyschew's illustrations show the 

spondylium completely supported by the median 

septum.

C. vogulicum var. krutolowskiensis (Khodalevitch 

1939, p. 27, pi. 12, figs. 1-2) from the upper Silurian of 

the Urals has a more elongate shell with much finer 

ribbing than does C. alaskense.

Conrad's species C. lagueatum from the Niagaran of 

Indiana (Hall and Clarke 1894, pi. 65, figs. 3-9) has 

a more elongate shell and the median septum is better 

developed, extending almost to the anterior end of the 

pedicle valve.
UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA 57

HoltedahTs species C. arcticum (1914, p. 5, pi. 6, 

figs. 5-7) was based upon very fragmentary remains. 

Judging from Holtedahl's description and illustrations 

this species has a smaller shell with much finer ribbing, 

the ribbing being more like that of C. vogulicum var. 

krutolowskiensis than of C. alaskense.

This species is a common one at locality 983, north 

shore of Heceta Island, southeastern Alaska.

Holotype, locality 983; U.S.N.M. 116567; paratypes, 

U.S.N.M. 116556-116566, 116568.

Genus Gypidula Hall, 1867 

Gypidula? sp.

Fragments of two pedicle valves are tentatively 

identified as Gypidula. They are from locality 2689, 

northeastern corner of Heceta Island, southeastern 

Alaska.

SUPEEFAMILY EHYNCHONELLACEA

Camartoechia Hall and Clarke, 1894

Camarotoechia reesidei Kirk and Amsden, n. sp.

Plate 8, figures 1-7; text figure 2

This species has a small biconvex shell with the 

brachial valve more convex. The pedicle beak is small, 

pointed, and generally erect, although it may be slightly 

hooked over the brachial. There is a sulcus on the 

pedicle valve which begins a short distance in front 

of the beak and becomes deep at the anterior end. This 

sulcus bears a conspicuous costella in the center; near the 

anterior end some individuals develop a low, indistinct 

costella on each side of the central one. The brachial 

valve bears a fold which begins near the posterior end 

and which becomes strongly developed at the anterior

end. Generally this fold has two well-developed costellae, but in a few individuals this central pair may 

be flanked on each side by another low indistinct rib. 

One specimen in the collection has 3 ribs on the fold 

and 2 in the sulcus. The lateral slopes of the fold 

and of the sulcus each bear 4 or 5 costellae; those next 

to the fold and sulcus are moderately high, but become 

progressively fainter toward the lateral margins.

The length of an average specimen is about equal to 

its width, measuring 9 mm. wide, 9 mm. long, and 5.5 

mm. thick; one specimen in the collection is slightly 

wider than long with a measurement of 10 mm. wide, 

8.5 mm. long, and 6 mm. thick.

Serial sections have been prepared to show the internal characters of this species (text fig. 2). These show 

that the pedicle valve has distinct dental plates, although these extend forward for only a short distance. 

In the brachial valve is a median septum which supports the divided hinge plate; a small portion of the 

upper side of this cruralium is covered by a plate, as 

shown in section G of text figure 2. Cooper (1944, p. 

311) mentions a similar structure in his discussion of 

the genus Camarotoechia. In C. reesidei this plate 

extends forward a short distance uniting the proximal 

ends of the two crura; the crura are fairly long and 

strongly arched.

In its size and shape this species resembles C. litchfieldensis and C. litchfieldensis var. marylandica (Schuchert 1903, p. 167; Swartz 1923, pp. 441-443, pi. 22, 

figs. 1-13), but both of these have narrower, more 

sharply angular costellae. Their internal characters 

have not been described. Camarotoechia litchfieldensis 

angustata Holtedahl (1914, p. 22, pi. 8, fig. 1) is larger 

and more elongate. C. reesidei is most similar to the

FIGURE 2.—Serial sections of Camarotoechia reesidei Kirk and Amsden n. sp. Brachial valve above, X 4. Peels at 

U. S. National Museum; U.S.N.M. 116603 a-1. Locality 2689, northeast end Heceta Island. Total length of specimen 8.9 mm. Distance in millimeters from posterior tip of ventral beak: A, 0.1; B, 0.4; C, 0.8; D, 1.1; E, 1.2; F, 

1.5; G, 1.6; H, 1.9; I, 2.0; J, 2.1; K, 2.2; L, 3.0.

962956—52——2
58 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

Brownsport species C. shannonensis (Ainsden 1949, pp. 

56-57, pi. 6, figs. 8, 9-16, 25), but the latter has 4 ribs 

on the fold and 3 in the sulcus. Internally, C. shannonensis (and also the other Brownsport species referred 

to Camarotoechia) has the cruralium uncovered, whereas 

C. reesidei has a plate over this structure.

This species is named for Dr. John B. Reeside, Jr., 

of the U. S. Geological Survey.

Holotype locality 2689 U.S.N.M. 116569; para types 

U.S.N.M. 116570, 116571.

About 18 specimens of this species were obtained at 

locality 2689, northeastern end of Heceta Island, southeastern Alaska.

Camarotoechia sp. 

Plate 10, figures 2-4

Four poorly preserved specimens of a second species 

of Camarotoechia were collected at locality 2689. These 

are considerably larger than C. reesidei and have a more 

pronounced fold and sulcus. Four low and rounded 

costellae occupy the sulcus and four or five the fold. 

The fragmentary condition of these specimens precludes 

specific identification.

Figured specimen U.S.N.M. 116572.

SUPEBFAMILY SPIRIFERACEA 

(as here used, includes all of the impunctate spire bearers)

Genus Atrypella Kozlowski, 1929

Atrypella scheii (Holtedahl) ? 

Plate 7, figures 12-22; text figure 3 

Lissatrypa scheii Holtedahl 1914 (pp. 24-26; pi. 7, figs. 9-12)

This species has both valves strongly, and about 

equally, convex, but in very large individuals the 

brachial is usually the greater. The mid-line of the 

pedicle valve is flattened along the anterior half to 

form a poorly defined sulcus which is produced into a 

tongue; the development of this sulcus varies, although 

it is usually conspicuous on mature valves. The anterior portion of the brachial valve is produced into a 

corresponding fold, that is poorly marked off from the 

lateral slopes; this fold and sulcus are best shown in 

the deflection of the anterior commissure (pi. 7, fig. 14). 

In outline the shell varies slightly, but generally is subrounded with most individuals having the width about 

equal to the length. A specimen of average size 

measures about 23 mm. long, 23 mm. wide and 17 mm. 

thick; one of the smallest in the collection is 11 mm. 

wide, 12 mm. long and 6 mm. deep; the largest is 27 

mm! wide, 26 mm. long and 19 mm. thick.

The shell of several specimens has been calcined to 

obtain an internal cast. Because the shell wall is 

rather thick the attempt was not entirely successful, 

but sufficiently good preparations have been made to 

show that this species has an interior similar to that of 

A. tennis. (See pi. 7, figs. 1, 9, 11; text fig. 5). In 

addition, serial sections have been prepared as shown 

in text figure 3. The principal difference between the 

interiors of A. tennis and A. scheii? is that the latter 

does not have as strongly developed brachial septum 

and pedicle platform (see description of A. tennis}.

The spiralium of this species is similar to that of 

Atrypa; it consists of 7 or 8 volutions with their apices 

dorsally directed (and tilted slightly toward the midline). The jugum is also like that of Atrypa.

Holtedahl's detailed description and illustrations 

reveal no specific differences between the Alaskan 

specimens and those from EUesmereland but, because 

shells of this type are rather difficult to identify from 

the literature and comparison of specimens from the 

two localities may well show that they represent different species, our identification is only tentative.

In his detailed description of the brachidium, 

Holtedahl noted that it is similar to that found in 

Atrypa reticularis, but he did not describe other internal 

features.

Holtedahl referred this species to Lissatrypa, but 

now there appears to be some question regarding the 

type of this genus. This name was proposed by 

Twenhofel with L. atheroidea designated as the type 

(1914, pp. 31-33) and during this same year Holtedahl's paper was published and the generic name 

Lissatrypa was used. Holtedahl (1914, p. 24) noted 

that the name had been proposed by Twenhofel in a 

"still unprinted work on the Ordovician and Silurian 

Faunas of the Anticosti Island near the Mouth of the 

St. Lawrence River in Eastern Canada." It was also 

noted that L. atheroidea of Twenhofel was the genotype, but if Twenhofel's paper, which appeared in 

October of 1914, postdates Holtedahl's, then this 

species is a nomen nudem and the type must be selected 

from one of. the two species which Holtedahl referred 

to this genus (L. scheii and L. phoca).

The determination of the genotype is especially 

important because on the basis of our Alaskan collections it seems very probable that the species scheii and 

phoca, as well as tennis, are not congeneric with 

atheroidea.

a b c d e

FIGURE 3.—Serial sections of Atrypella scheii (Holtedahl)?. Brachial valve above, X 1.5. Locality 1019, east end Heceta 

Island. Peels of these sections are located at the U. S. National Museum; U.S.N.M. 116604 a-e. Total length of 

specimen 25 mm. Distance in millimeters from posterior tip of pedicle beak: A, 2.0; B, 3.0; C, 4.0; D, 5.0; E, 6.0.
UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA 59

Amsden wrote to Dr. Holtedahl and to The Society 

of Arts and Sciences of Kristiania in an attempt to 

determine the exact date of publication of his paper, 

but it was impossible to obtain the information desired 

and we are therefore following general usage in accepting L. atheroidea as the genotype.

Twenhofel described and illustrated the brachidium 

of L. atheroidea and this seems to be the same as that 

found in the Ellesmereland species as well as in the 

Alaskan specimens and in Atrypa; it is also the same as 

that of Lissatrypa decaturensis (Amsden, 1949, p. 64, 

pi. 9, figs. 16-23) from the Brownsport formation. 

Twenhofel did not, however, discuss the pedicle or 

brachial musculature. Through the courtesy of Professor C. O. Dunbar the types of L. atheroidea were 

borrowed from Peabody Museum at Yale University. 

Two paratypes were calcined to obtain internal casts 

(pi. 7, figs. 23, 30) and a third was serially sectioned 

(text fig. 4) to reveal internal characters. The brachial 

valve has a rather ponderous hinge plate which is 

cleft at the posterior end, and which then gives way to 

a thick median septum. The pedicle valve has a narrow and deep delthyrial cavity; the diductor scars 

are narrow, deep, and separated posteriorly by a thick 

septum. This septum is cleft at the posterior end by 

a narrow valley which presumably represents the point 

of attachment of the adductors.

The. genotype of Atrypella is A. prunum Dalman 

(Kozlowski 1929, pp. 173-176) which is a fairly large 

species, rather strongly biconvex and with a smooth 

exterior. It resembles Atrypa in general shape, but 

the pedicle valve is more strongly convex, as in 

Atrypella scheii? and A. tennis. Specimens of Lissatrypa are much smaller and not so strongly biconvex.

The brachidium of Atrypella is apparently like that 

of Lissatrypa and Atrypa. The pedicle musculature

of Atrypella, however, seems to be much less deeply 

impressed than that of Lissatrypa; it lacks the strongly 

indented diductor scars and high separating platform 

which characterizes Lissatrypa. The brachial valve 

of Atrypella has a much more weakly developed 

median septum and the hinge structures are not as 

massive (Kozlowski 1929, text fig. 57). The internal 

structures of the Alaskan specimens of A. scheiif and 

A. tennis are much more like those of Atrypella than 

Lissatrypa.

A. scheii? is larger and more strongly biconvex than 

A. tennis.

Holtedahl's specimens came from "B, lower part, 

Reindeer Valley, B, lower part, Seal Bay," southwestern corner of Ellesmereland. The specimens in 

the collections under study are from localities 1019 and 

1589, at the east end of Heceta Island, and 2689, 

northeastern corner of Heceta Island.

HypotypesU.S.N.M. 116573-116578.

Atrypella Kozlowski, 1929 

Atrypella tenuis Kirk and Amsden, n. sp.

Plate 7, figures 1-11; text figure 5

This shell is biconvex with the brachial valve having 

a convexity which is greater than the pedicle. The 

pedicle beak is small and only slightly hooked over the 

brachial; the posterior half of the pedicle valve is 

rather sharply convex, but toward the anterior end it 

becomes flattened, developing a shallow sulcus which 

is produced into a tongue (pi. 7, figs. 2, 7). On the 

posterior half, the brachial valve is evenly rounded, but 

toward the anterior end it develops a fold which corresponds to the pedicle sulcus. The surface of both 

valves is smooth, except for faint growth lines.

The width of the shell is about equal to the length, 

but some individuals are slightly wider or narrower than

O O

FIGURE 4.—Serial sections of Lissatrypa atheroidea Twenhofel. Brachial valve above, X 3. Specimen from which these 

sections were made came from the Silurian Jupiter formation, West Jupiter Cliffs, Anticosti Island. Peels of sections 

are at Peabody Museum, Yale University, Oat. No. 17717. Total length of specimen 9.2 mm. Distance in millimeters from posterior tip of pedicle beak: A, 0.1; B, 0.6; C, 1.0; D, 1.1; E, 1.3; F, 1.6; Q, 1.9; H, 2.3; I, 2.6; J, 3.1; K, 3.9; 

L, 4.7; M, 5.2.
60 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

long. A specimen of average size measures about 19 

mm. long, 19 mm. wide and 11 mm. thick; one of the 

smallest in the collection measures 7 mm. wide, 8 mm. 

long and 3.5 mm. thick. The largest is 21 mm. wide, 

22 mm. long and 12 mm. thick.

In the pedicle interior (pi. 7, fig. 9; text fig. 5) the 

teeth are moderately stout and arise from the lateral 

slopes with no trace of dental plates. There is a broad, 

low, poorly defined platform which begins in front of 

the beaks, extending for about one-third the length 

of the valve; bordering this platform are shallow, 

poorly defined grooves which may represent the point 

of attachment for the diductor muscles.

In the brachial interior the muscle scars are poorly 

developed. The hinge plate of this valve is divided, 

giving a rather conspicuous notothyrial cavity; a low, 

median septum appears near the posterior end of this 

cavity and extends for about a third the length of the 

valve (pi. 7, figs. 1, 11, text fig. 5; compare to Kozlowski 

1929, text fig. 57).

The internal structures of Atrypella tennis are similar 

to those of the Alaskan specimens of A. scheiil On the 

latter, however, neither the brachial septum nor the 

pedicle platform is as well developed as on A. tennis. 

The spiralium and jugum of both species is similar to 

that of Atrypa reticnlaris.

o O O

FIGURE 5.—Serial sections ol Atrypella tenuis Kirk and Amsden n. sp. Brachial valve 

above, X 3. Peels of sections at U.S. National Museum; U.S.N.M. 116605 a-1. 

Locality 1005, south shore Kosciusko Island. Distance in millimeters from 

posterior tip of pedicle beak: A, 0.3; B, 0.6; C, 0.9; D, 1.6; E, 1.7; F, 2.1; G, 2.3; 

H, 3.0; I, 3.6; J, 4.6.

The shell of this species is smaller and less robust 

than that of A. scheiil Specimens of the latter that 

are of similar width and length are much thicker, as 

shown in the following measurements:

Atrypa tenuis_. 

Atrypa scheiil.

Dimensions in millimeters

ThickWidth Length ness 

.__..__________ 21 21 12

.___________ 22 22 17

Khodalevich described several new species of Lissatrypa from the upper Silurian of the Urals. The shape 

and size of several of these species suggest that they 

should be referred to Atrypella Kozlowski rather than 

Lissatrypa Twenhofel, but the descriptions (English 

summary) are very brief and there are no illustrations 

of interiors. The species which seems to be most 

similar to A. tenuis in its external appearance is L. 

penitns Khodalevich (1939, p. 105, pi. 24, figs. 2, 5), 

but the latter appears to have a much greater convexity 

and a more rounded outline.

This is one of the most abundant species in the collections. All specimens from locality 1005, south shore of 

Kosciusko Island.

Holotype, locality 1005, U.S.N.M. 116579; paratypes 

116580-116583.

Atrypella borealis Kirk and Amsden, n. sp.

Plate 8, figures 18-22; text figure 6

The shell is subtriangular in outline with a short 

hinge line, that is about one-third the maximum width 

of the shell. Its lateral profile is biconvex, with the 

pedicle valve slightly deeper than the brachial* The 

pedicle valve is rather evenly convex except for a 

shallow but distinct sulcus which appears near the 

anterior end; the beak of this valve is small and tightly 

hooked over the brachial. There is only the faintest 

trace of a fold on the anterior portion of the brachial 

valve, with the rest of the shell evenly convex. Both 

valves are completely smooth except for indistinct 

growth lines.

The collections under study include only a few specimens of this species and only two are well preserved. 

One of these measures 10.5 mm. wide, 10 mm. long 

and 8 mm. thick; the other is 11 mm. wide, 10 mm. 

long and 7 mm. thick.

One imperfect specimen was sectioned to reveal the 

internal characters. The spires were not preserved, 

but the other internal structures are shown in text 

figure 6 and appear to be similar to those of A. tennis 

and A. scheiil (compare text fig. 6 with figs. 3, 5). 

The shell-wall of A. borealis is relatively thick for a

b

FIGURE 6.—Serial sections of Atrypella borealis Kirk and Amsden, n. sp. Brachial valve above. Locality 1005, south 

shore Kosciusko Island. Peels of sections at U. S. National Museum; U.S.N.M. 116606 a-d. Distance in millimeters 

from posterior tip of pedicle beak: A, 0.1; B, 0.2; C, 0.9; D, 1.2; E, 2.7.
UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA 61

shell of this size and in this respect it is similar to 

Lissatrypa atheroidea (genotype of Lissatrypa', see text 

fig. 4 and also discussion of A. scheiit}. A. borealis 

differs from L. atheroidea in lacking the strong median 

platform in the pedicle valve, and the brachial hinge 

plate is much less ponderous.

This is a smaller species than A. tennis. When compared to immature specimens of the latter which are of 

a comparable size, A. borealis is seen to be more strongly 

convex; also, the immature specimens of A. tennis lack 

the ventral sulcus which is so clearly defined on A. 

borealis.

A. scheiit is much larger, and does not develop a 

ventral sulcus until it is about half grown.

The specimens of Lissatrypa linguata (Buch) [Atrypellal linguata} figured by Khodalevich (1939, pi. 20, 

figs. 6-7) are more elongate and appear to have a 

better-developed sulcus than does A. borealis.

Atrypella shrocki (Cooper 1942, p. 234) is a larger 

species with a more prominent fold and sulcus.

Only 5 specimens were obtained at locality 1005, 

south shore of Kosciusko Island.

Holotype, locality 1005, U.S.N.M. 116584; paratypes 

116585.

Nucleospira Hall, 1859 

Nucleospira hecetensis Kirk and Amsden, n. sp.

Plate 7, figures 24^29, 31-32

The anterior portion of the shell is rounded in outline, 

but the hinge line is straight and about two-thirds the 

maximum width of the shell, thus this portion of the 

outline is slightly truncate with moderately well-defined 

shoulders. In lateral profile the shell is biconvex with 

the convexity of the valves about equal. The pedicle 

beak is small, pointed, and sharply hooked over the 

dorsal.

The surface of well-preserved specimens is covered 

with a mat of fine spines. Where these spines have 

been abraded away, as is common, the surface appears 

smooth except for irregularly spaced, concentric 

growth lamellae; generally the surface shows small 

pits that mark the places of attachment of the spines.

Six specimens in the collections have been referred 

to this species; 4 of these average 12 mm. wide, 11 mm. 

long and 8 mm. deep; the smallest in the collection is 

7 mm. wide, 6 mm. long and 4 mm. thick; the largest 

individual is 18 mm. wide, 14 mm. long and 10 mm. 

thick.

No interiors have been seen.

Nucleospira hecetensis most closely resembles the 

Helderberg species N. ventricosa (Hall 1857, p. 57; 

Hall and Clarke 1894, pi. 48, figs. 2-6, 18). A comparison of specimens from the Helderberg group with those 

from Alaska shows that N. hecetensis has a somewhat 

longer hinge line with moderately prominent shoulders, 

whereas N. ventricosa is more strongly biconvex and has

a shorter hinge with the shell sloping uniformly away 

from the beaks.

Specimens of N. swartzi Maynard (in Swartz 1913, 

p. 432, pi. 73, figs. 15-17) from the Keyser limestone of 

West Virginia have a more strongly convex ventral 

valve and a flatter dorsal valve than N. hecetensis.

There are six specimens in the collection from locality 

2689 northeast end Heceta Island.

Holotype locality 2689; U.S.N.M. 116586; paratypes 

U.S.N.M. 116587, 116588.

Alaskospira Kirk and Amsden, n. gen.

I

Genotype: Alaskospira dunbari, Kirk and Amsden, n. sp.

The only known species of this genus, Alaskospira 

dunbari, has a biconvex shell with the pedicle valve 

deeper than the brachial. The pedicle beak is prominent 

and hooked at its posterior end; this valve has a fairly 

well developed palintrope that is not sharply marked off 

from the rest of the shell. Both pedicle and brachial 

valves are rather uniformly convex, except for a narrow, 

poorly defined pedicle sulcus and brachial fold near the 

anterior end. The shell in outline is somewhat rounded 

with the greatest width a short distance anterior to the 

hinge line.

Well preserved specimens bear concentric lamellae 

(see pi. 7, fig. 47) but some specimens that have had the 

lamellae removed by abrasion show only faint, widely 

spaced costellae, especially along the anterior margins. 

No spines have been observed, perhaps due to lack of 

preservation.

The pedicle interior has well developed teeth unsupported by dental plates. The diductor scars are 

narrow, deeply impressed and about one-third the 

length of the valve; separating them is a thickened 

platform or ridge that extends nearly to the anterior 

end of the shell (pi. 7. fig. 39; text fig. 7).

In the brachial valve there are well developed 

sockets; the ribbon appears to develop on each side of 

these sockets as flat plates that help to define a deep, 

notothyrial cavity at the posterior end. A low, rounded 

septum appears a short distance in front of the beak and 

extends forward for a few millimeters and is then 

replaced by a shallow depression. Anteriorly, this 

depression or trough is bordered on each side by a ridge 

of shell material (text fig. 7).

There are only about 5 volutions to each spire; the 

apices of these spires are laterally directed. Jugum 

not observed.

Externally this genus is similar to Eoreticularia 

(Nalivkin 1930, p. 198; genotype Spirifer indijferns 

Barrande 1879, pi. 3, figs. 4-7). They are closely 

similar in outline, in lateral profile and possibly in 

ornamentation. In describing the ornamentation, 

Nalivkin states "Surface covered with multitudinous 

thin, densely set, lamellar, concentric growth-ridges.
62 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

Spines sometimes absent." The principal difference 

between Eoreticular^a and Alaskospira lies in the internal characters. Nalivkin does not give a very detailed 

description of these characters, but he does state that 

dental lamellae are present; in Alaskospira the lamellae 

are absent. Nalivkin also states that Fredrick's genus 

Reticulariopsis also possesses dental plates.

Externally Alaskospira somewhat resembles Spirinella (Johnston 1941, p. 161); the only species referred 

to this genus is the type, S. caecistriata, which is described as ornamented with "only very fine radiating 

striae superimposed on the fine, concentric growth 

lines." The serial sections which are figured in Johnston's paper show that Spirinella has well developed 

dental plates and lacks the deep, discrete, subparallel 

muscle scars of Alaskospira.

The pedicle interior of Alaskospira has some similarities to Amboecolia (Hall 1860, p. 71; Hall and Clarke 

1894, p. 54), which lacks dental plates and which has a 

ventral musculature described as "quite restricted, consisting of narrow, elongate diductors enclosing an almost 

linear adductor" (Hall and Clarke 1894, p. 55). The 

brachial interiors, however, are different; in Amboecolia 

the muscle scars are located toward the anterior and 

consist of four well defined scars, whereas in Alaskospira 

this portion of the brachial valve is occupied by a 

single, narrow trough. Amboecolia umbonata appears 

to lack any trace of radial costellae and the concentric 

lamellae are irregular and widely spaced whereas those 

of Alaskospira dunbari are closely spaced.

Eospinfer (Schuchert) has better developed radial 

costellae than Alaskospira and lacks the concentric 

lamellae. Internally, Eospirifer has well developed 

dental plates.

Alaskospira dunbari Kirk and Amsden, n. sp. 

Plate 7, figures 33-40, 47; text figure 7

The lateral profile of this shell is biconvex with the 

pedicle valve about twice as deep as the brachial. 

The pedicle beak is pointed and sharply hooked at its 

posterior end; there is a moderately well developed 

palintrope on this valve that is not sharply marked off 

from the lateral slopes. Most pedicle valves are uniformly convex except for a faint mid-line flattening, 

which in a few individuals is developed into a shallow, 

poorly defined sulcus. The bracbial palintrope is 

narrow; this valve is uniformly convex, except for an 

indistinct fold on the anterior half.

The surface of most individuals has been worn completely smooth, but a few well preserved specimens 

show numerous closely spaced concentric lamellae. 

(See pi. 7, fig. 47.) Some specimens which have been 

abraded only slightly so that the concentric lamellae 

are absent will show faint costellae with relatively wide 

interspaces; where the concentric lamellae are present 

these costellae are masked and where the shell is more 

deeply worn, as is commonly the case, this radial ornamentation disappears.

The pedicle and bracbial interiors have been described in the generic description.

Specimens of average size measure about 17 mm. 

wide, 15 mm. long, and 10 mm. deep; the largest individual in the collection is 22 mm. wide, 19 mm. long, 

and 12 mm. deep.

Externally Alaskospira dunbari resembles Eoreticularia indifferns (Barrande 1879, pi. 3, figs. 4-7) but the 

latter has a more prominent fold and sulcus. The 

internal differences have already been discussed under 

generic description.

o

O

m

FIGURE 7.—Serial sections of Alaskospira dunbari Kirk and Amsden, n. sp. Brachial valve above, X 2. Peels of sections at 

U. S. National Museum; U.S.N.M. 116607 a-m. Locality 1005, south shore Kosciusko Island. Distance in millimeters from posterior tip of pedicle beak: A, 0.3; B, 1.8; C, 2.3; D, 3.0; E, 3.3; F, 3.8; G, 4.1; H, 4.6; I, 5.5; J, 6.6; 

K, 7.4; L, 8.4; M, 9.4.
UPPER SILURIAN BRACHIOPODS FROM SOUTHEASTERN ALASKA 63

Spirifer (Martinia1?) pseudopentameriformis (Khodalevich 1939, p. 110, pi. 28, fig. 6) is somewhat wider in 

proportion to its length, than is Alaskospira dunbari. 

The ornamentation of this species is said to consist of 

"simple, close-set growth lamellae. Inner layer showing fine radial costae(?)." Khodalevich does not discuss the internal characters beyond stating that they 

are similar to Spirifer pentameriformis Tschernyschew 

(1893, p. 168, pi. 6, figs. 5-9; internal characters not 

discussed).

In general shape Alaskospira dunbari resembles 

Spirifer modestus var. striatissimus Holtedahl (1914, 

p. 26-27, pi. 7, fig. 2) from Ellesmereland which, however, is much smaller and has dental plates.

In shape A. dunbari resembles immature specimens 

of Harpidium.

This species is named for Prof. C. O. Dunbar, of Yale 

University.

There are about 25 specimens of this species in the 

collections from locality 1005, south shore Kosciusko 

Island.

Holotype locality 1005; U.S.N.M. 116589; paratypes 

U.S.N.M. 11659-116593.

Genus Atrypa Dalman 1828 

Atrypa cf. Atrypa reticularis (Linnaeus)

Plate 8, figures 8-17 

Anomia reticularis Linnaeus (1767, p. 1152)

The specimens of Atrypa in the Alaskan collections 

are moderately strongly biconvex shells with the 

brachial valve having much the greater convexity. The 

umbonal area of the pedicle valve is sharply convex, but 

the lateral slopes become flattened; on the anterior half 

of mature shells a fairly deep sulcus is commonly produced into a tongue. The posterior half of the brachial 

valve is strongly and evenly convex; toward the anterior end a fold is developed, but this is not sharply 

marked off from the lateral slopes. The pedicle beak 

is small, pointed and sharply hooked over the brachial 

valve.

The surface is covered with low, rounded costellae, 

about 9 occupying a space of 5 mm. These costellae 

are crossed by irregularly spaced concentric lamellae 

that are best developed on the anterior portion of the 

shell. Several specimens have well developed spines 

where the lamellae cross the crests of the costellae.

The ratio of width to length varies considerably: 

average specimens are about 21 mm. long, 21 mm. 

wide, and 13 mm. thick, but some individuals are wider 

than long and some longer than wide. One of the 

largest specimens is 24 mm. long, 27 mm. wide, and 

13 mm. thick; another large one is 26 mm. long, 24 mm. 

wide, and 13 mm. thick.

This species is common at locality 2689; there are 

also some specimens from locality 1005; these are poorly

preserved, but seem to be similar to those from locality 

2689, although the ribbing may be slightly coarser. 

Figured specimens U.S.N.M. 116594-116598.

Delthyris Dalman 1828

Delthyris? sp. 

Plate 7, figures 42-46

A specimen in the collections studied has the general 

shape of the genus Delthyris. The spines and concentric lamellae that are characteristic of this genus are 

not present but the shell is deeply worn and this absence may be due to poor preservation. There is a 

rather prominent pedicle fold and brachial sinus with 

about 5 rounded plications on each side. The shell is 

10 mm. wide, 7 mm. long, and 6 mm. thick.

One specimen from locality 1005. Figured specimen 

U.S.N.M. 116599.

Eospirifer Schuchert 1913

Eospirifer sp. 

Plate 10, figure 6

A few poorly preserved specimens are referred to the 

genus Eospirifer. This species has a distinct pedicle 

sulcus with plicated lateral slopes (pi. 10, fig. 6), and 

resembles Eospirifer irbitensis (Tschernyschew; Khodalevitch 1939, pi. 27, figs. 1, 2) from the Urals, although the Alaskan species is much smaller and has less 

distinct ribs.

The specimens at hand are exfoliated, but one or 

two have enough of the original shell material to suggest that they bore radial lines.

Locality 2689, northeastern end of Heceta Island; 

southeastern Alaska.

Figured specimen U.S.N.M. 116600.

Genus Howellella Kozlowski 1946 

( = Crispella Kozlowski 1929)

Howellella sp. 

Plate 7, figure 41; plate 10, figures 7-9

Four incomplete specimens are identified as Howellella. They are rather strongly biconvex with a narrow 

but distinct pedicle sulcus and a corresponding brachial 

fold; the lateral slopes are smooth. None of the specimens show the pedicle beak very clearly but it is 

probably pointed and erect. The surface has concentric lamellae that bear small spines (pi. 7, fig. 41). 

The general shape and ornamentation of the species is 

thus like that of Crispella, although it is not a costate 

shell as is the genotype, H. crispa. One individual has 

the pedicle beak broken and shows well-developed 

dental lamellae but no median septum. The other 

internal characters are unknown.
64 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1951

Locality 2689, northeastern corner of Heceta Island; 

southeastern Alaska. 

Figured specimens U.S.N.M. 116601, 116602.

REFERENCES

Alexander, E. S., 1948, A revision of the genus Pentamerus 

James Sowerby 1813 and a description of the new species 

Gypidula bravonium from the Aymestry limestone of the 

main outcrop: Geol. Soc. London, Quart. Jour., vol. 103, 

pt. 3, pp. 143-161, one plate plus text figs.

Alexander, E. S., 1951, Proposed use of the plenary powers to 

prevent the confusion which would result, under a strict 

application of the "Regies," from the sinking of the name 

"Conchidium" as a synonym of "Pentamerus" Sowerby, 1813 

(Class Brachiopoda) and the transfer of the latter name to 

the genus now known as "Conchidium": Bull. Zoological 

Nomenclature, vol. 2, pt. 3, pp. 89-94.

Amsden, T. W., 1949, Stratigraphy and paleontology of the 

Brownsport formation (Silurian) of western Tennessee: 

Peabody Mus. Nat. History, Yale Univ., Bull. 5, pp. 1-138, 

pis. 1-34, 30 text figs.

Barrande, J., 1879, Systeme Silurien du centre de la Bohe'me: 

Prague, vol. 5, pt. 1, pp. i-xiv, 1-226, pis. 1-71.

Cooper, G. A., 1942, New genera of North American brachiopods: 

Jour. Wash. Acad. Sci., vol. 32, no. 8, pp. 228-235.

———— 1944, Chapter IX, Phylum Brachiopoda, in Shimer and 

Shrock, Index Fossils of North America, pp. 277-365, pis. 

105-143.

Dalman, J. W., 1828, Uppstallning och Beskrifning af di i 

Sverige funne Terebratuliter:K. svenska Vetensk. Akad. 

Handl., for 1827, pp. 85-155, pis. 1-6.

Davidson, T., 1853, Monograph of British fossil Brachiopoda, 

Volume 1, Introduction: Palaeontographical Soc. London, 

pp. 1-136, pis. 1-9.

Foerste, A., 1909, Fossils from the Tilurian formations of Tennessee, Indiana and Iliintis: Denison Univ. Sci, Lab. Bull., 

vol. 14, pp. 61-107, pis. 1-4.

Hall, James, 1857, Description of Palaeozoic fossils: New York 

State Cab., Nat. History, 10th Kept., pp. 39-180.

———— 1859, Observations on the genus Nucleospira: New York 

State Cab. Nat. History, 12th Ann. Rept., pp. 24-26, illus.

———— 1860, Observations on Brachiopoda: New York State 

Cab. Nat. History, 12th Ann. Rept., pp. 65-75, illust.

Hall, James, and Clarke, J. M., 1893, An introduction to the 

study of the genera of Palaeozoic Brachiopoda: Palaeontology of New York, vol. 8, pt. 1, pp. i-xvi, 1-367, pis. 1-20, 

39 text figs.

———— 1894, An introduction to the study of the genera of 

Palaeozoic Brachiopoda: Palaeontology of New York, vol. 

8, pt. 2, pp. i-xvi, 1-394, pis. 21-84, text figs.

Holtedahl, O., 1914, On the fossil faunas from Per Schei's Series 

B in southwestern Ellsmereland: Report of the second 

Norwegian Arctic Expedition in the "Fram" 1898-1902, 

no. 32 (Published by Videnskabs-Selskabet I Kristiania), 

pp. 1-48, pis. 1-8.

Johnston, J., 1941, Studies in Silurian brachiopods, 1, Description of a new genus and species: Proc. Linnaean Soc. New 

South Wales, vol. 66, pp. 160-168, 1 pi., 2 text figs.

Khodalevich, A. N., 1939, Upper Silurian Brachiopoda of the 

eastern Urals: Trans. Ural Geol. Service (Geol. Service of 

USSR), pp. 1-135, pis. 1-28.

Kirk, Edwin, 1922, Brooksina, a new pentameroid genus from 

the upper Silurian of southeastern Alaska: Proc. U. S. 

Nat. Museum, vol. 60, Art. 19, pp. 1-8, 1 pi.

——— 1925, Harpidium, a new pentameroid brachiopod from 

southeastern Alaska: Proc. U. S. Nat. Museum, vol. 66, 

Art. 32, pp. 1-7, 2 pis.

1926, Cymbidium, a new genus of Silurian pentameroid

brachiopod from Alaska: Proc. U. S. Nat. Museum, vol. 

69, Art. 23, pp. 1-5, 1 pi.

Kozlowski, R., 1929, Brachiopodes gothlandiens de la Podolie 

polonaise: Palaeont. Polonica, vol. 1, pp. i-xiii, 1-254, pis. 

1-12, 95 text figs.

———— 1946, Howellella a new name for Crispella Kozlowski, 

1929. Jour. Paleontology, vol. 20, p. 295.

Linnaeus, "C., 1767, Systema naturae, 12th ed.: pp. 553-1327.

Merriam, C. W., 1940, Devonian stratigraphy and paleontology 

of the Roberts Mountains region, Nevada: Geol. Soc. 

America, spec, paper no. 25, pp. 1-114, pis. 1-16.

Nalivkin, D., 1930, Brachiopods from the upper and middle 

Devonian of the Turkestan: Me'moires du Comit6 Geologique. Nouv. ser., Livr. 180 (Russia), pp. 1-221, pis. 1-10.

Oehlert, D. P., 1887, in P. H. Fischer, Manuel de Conchyliologie, 

pp. 1189-1334, pi. 15, text figs.

Poulsen, C., 1943, The Silurian faunas of north Greenland 2. 

The fauna of the Offley Island formation, part 2 Brachiopoda: Meddelelser om Gr0nland, Bd. 72, no. 3, pp. 1-59, 

6 pis.

Schuchert, Charles, 1903, On the Manlius formation of New 

York: Am. Geologist, vol. 31, pp. 160-178, text figs.

Schuchert, Charles, and Cooper, G. A., 1932, Brachiopod genera 

of the suborders Orthoidea and Pentameroidea: Peabody 

Mus. Nat. History, Yale Univ., Mem., vol. 4, pt. 1, pp. 

i-xii, 1-270, pis. A, 1-29, 36 text figs.

St. Joseph, J. K. S., 1938, The Pentameracea of the Oslo Region. 

Being a description of the Kiaer collection of pentamerids: 

Norsk geologisk Tidsskrift Bd. 17, pp. 225-336, pis. 1-8, 

text figs.

Sowerby, J., 1813, The mineral conchology of Great Britain: 

London, vol. 1, pp. 153-168, pis. 68-72.

Swartz, C. K. and others, 1913, Lower Devonian: Maryland Geol. 

Survey, pp. 1-560, pis. 1-98.

———— 1923, Silurian: Maryland Geol. Survey, pp. 1-794, pis. 9-67. 

Tschernyschew, T., Die Fauna des Unteren Devon am Ostabhange des Ural: Me'moires du Comite G^ologique, vol. 4,

no. 3, pp. 1-221, pis. 1-14. 

Twenhofel, W. H., 1914, The Anticosti Island faunas: Canada

Dept. Mines, Mus. Bull. no. 3, Geol. Ser. No. 19, pp. 1-39,

pi. 1.
INDEX

[Italic numbers indicate descriptions]

Abstract—________._________— ___________________ 53

acutum, Cymbidium..... .________________________.____.._. 53

alaskense, Conchidium..-......_._________._________ 53,54,55,pis. 8,9,10

alaskensis, Brooksina_____--___________________._.. 53

Alaskospira------........._____.__-__.__________.______ 61

dunbari-___.__________________________.-_ 53,54, 62, pi. 7 

Ambocoelia.-.-.....-_-__ —______.--_.___-_.-._____.- 62

umbonata.-—_-—_—___—,_.______—-___-_..._______________ 62

angustata, Camarotoechia lifchfieldensis........... ________________ 57

Anomia reticularis.- ...........———_.-__._._____________________ 63

arctica, Stenoschismadeckerensis. _.____________________._ 54

ardicum, Conchidium _______________________________ 54,57

atheroidea, Lissatrypa.. ..... ________________________ 58,59,61, pi. 7

Atrypa reticularis..............____.____.-_-.___._ 53,54,58,59, 63, pi. 8

Atrypella- __.____________________________. ________ 54,55

borealis____.______________________________ S3,54, 60, pi. 8

prunum. _________-_________-_.-..___________ 59

scheii————————————- — .— — ——————.- 53,54,58,60,pi. 7

shrocki................................... ___________________ 54

tennis...................................................... 53, 54,58, 69, 61, pi. 7

B 

borealis, Atrypella,-.--............................................. .. 53,54, 60, pi. 8

Brooksina—........................................................______ 53,54

_________________________________._______ 53

______________________________________ 54

————— ——— ——— ——— ————— ——— ———— ————— ——— 54

—— ——— ——— — ————— . ———— ——————— ——— ———— _ 54

conjugula. 

crassa.....

caecistriata, Spirinella. 

Camarotoechia--------

litchfieldensis. .....

angustata. .-..

marylandica...

prognostica_

— ——— — ————— —————————— ———— ——— 62

.—— — -—.—.. __.*—.—.„....—.......... 57

——————————————————— ———— 57

———————————————————— ————— 57

———————————————————— ————— 57

———————————————————————— 54

reesidel........................................................... 53, 54, 67, pi. 8

shannonensis____________________________________ 58

sp__—-_ — — — ..————— —— —————————————— 54,58,pi. 10

coeymanensisprognostica, Gypidula...___________________ 54

Conchidium.... ___________________________________________ 54

ataskense.-..... _____ ___________________ 53,54,55, pis. 8,9,10

arciicum-. ____-___-__.__--_______________________ 54,57

knighti..................................................._———________ 54,56

laqueatum. -_._____....____________________________ 56

vogulicum.... - — - — — ___- — — _—_________________._. 54,56

krutolowskiensis___-__-_________— —___..___________ 54,56,57

conjugula, Brooksina---------------------... _ — — __-_______.___._. 54

costulata, Cymostrophia^... _.______________________ 53,54,55,pi. 10

Sfrophomena— __________________________.______________ 55

crassa, Brooksina......____ __________________._______ 64

crispa, Howellella-... _______-_-__-____________________ 63

Orispella-________________________________________ 63

Cymbidium.._____._______________________________ 53,54

acutum.,.--.... _-._____-_--_.________________________ 53

latum........--..-.--_--__-._--____________________________ 53

Cymostrophia costulata-_____.__...______________ 53,54,55,pi. 10

D 

Dalmanellacea_________________________________________... 55

decaturensis, Lissatrypa...... ___-_____._______._____________ 59

deckerensis ardica, Stenoschisma.... ___________________________________ 54

DeUhyrisf sp_ __________________________________________ 53, 54, 63, pi. 7

dumbari, Alaskospira-.. _________________._____________ 53, 54, 62, pi. 7

E

elongata, Lissatrypa penitus.. ___________.__________________ 55

Eoreticularia... ______— -__.-__._______________________ 61,62

indifferns.----------------------- _._--.___________________________ 62

EospiriferirbUensis-.____-______.._________________________ 55,63

radiatus..... __._____._______________________________ 54

sp_.—————————————— ——— ————— ———— ———— 53, 54, 63, pi. 10

euglypha, Strophonella......................___________________ 54

G Page

Gypidula coeymanensis prognostica--- ——— __._--____-__-----_ — _ — —— _.-_. 54 

sp——————————————————————— — — ———— — 53,54,57

H 

Harpidium-... .__________-___________-___________ 53,54,55,63

insignis... _____-___________ —._ — — _ ——— _____ ——— _ —___ —— — 53,54

.0.1.8.-.—— —— — — .— — ———————————— — — — 53

hecetensis,Nucleospira- _________—. —— __________ — _______—_ — — 53,54, 61, pi. 7

Holtedahlcited——— — — — ——————— ——————— —— —— 54

Howellella---— ————————— ————— —————————— 63

crispa........ __________________————————_————_—————————— 63

sp________——- — — — ———— ———— — —— —— —— —— —— 53,54, 63, pis. 7,10

I 

indifferns. Eoreticularia-------... ________ —— ____ — _____ ——— _ — — ___—— 62

Spirifer..-—..——————————————————— —— — ——— 61

insignis, Harpidium.... _——___ — __ — ___ —— — _____ — _— —— __———— 53,54

interstriata sinuata, Schuchertella,----.......—....... __-_———————————— 54

Introduction________——__ ——— __ — — __ — ___ — _ — ——— — ——— 53

irbitensis, Eospirifer _______________ ——— _ ————— _——————————————— 55,63

Isorthis sp_________________ — _-__—— —— —— ______ —— — — - — — — —53,54

Khodalevich citedKirk cited————

—— ——— ——— ——— — ——— —— —— —_----------- 54

................ — ————— ——— — — — — — — — 54

knighti, Conchidium--- ...—— _— — ——— --- — — _ — ---- —— — _ — . — —— 54,56 

krutalowskiensis, Conchidiumvogulicum-..-- ....— _ —. — _ —— ___ —— — - 54,56,57

laqueatum, Conchidium---.......—. ——— _____ ——— _ — __-__ — — — — _ 56

latum, Cymbidium.... ———————————————————————-———————— 53

lotus, Harpidium-------- ....— — __—-_— — _ ——— — ___—_. — — —— _- 53

Lissatrypa-- —— — — _ — _ — --__ ——— ___-_--__-_-_--------_-_------ — — 60

atheroidea-.— ————————————————————— 58,59,61, pi. 7

decaturensis—----------- .-— --___ —— — __ — ——— —— — —— — —— —— 59

penitus-.......................................-.——-.. ————————— 55

elongata.... -_—__ —— _ — — -_ ——— - —— — ——— ---- ——— ----—— 55

phoca-------—--..-------------- _-_———————————————————— 58

scheii.----------- ...—— ___ —— ——. ______ — _ ——— _ — _ ——— — - — — - 58

litchneldensis, Camarotoechia------ — — __ — — _-_- — —— — —— --- —— ----- 57

angustata, Camarotoechia------------------- — --_- — — - — --------- —— - 57

marylandica, Camarotoechia.-- ———— ______ ——. — __ ———— ——— —— -- 57

prognostica, Camarotoechia-.-- .....— _-_—__- —— _ — —— — —— — - — - 54

Localities—-.--------------------------------------------------------------- 53

M 

magnus, Pentamerus..--.—————-_ —._-_- —— __.- ------- — - —— __--_— 55

(MartiniaT) pseudopentameriformis, Spirifer--------------- ...------- — __.___- 55,63

marylrndica, Camarotoechia litchfieldensis- ........... ________ —— _ —— — ___- 57

modestus striatissimus, Spirifer..----------. ...-___ — _-- — -—-.- — _ — -—— 54,63

N 

Nucleospira hecetensis...-----. —————— --- ——— - —— - —— --- —— -- 53,54, 81, pi. 7

swartzi........ —— __ ——— _____ _ _ — _ —.... — —— _________._.___-_- 61

ventricosa... ——— —— ___________ — _ — ___ —— ____-__--__-_--------_—— 61

penitus, Lissatrypa————_ — — __ ——- —— -- — __-_---_-- — — — - — -— 55

elongata, Lissatrypa.-- — _ — — — _- —_ —— _._--___ — -___ — ___———— 55

Pentameracea..--------- ————— -- — — —— -____ —— ------ — _ — — -- 55

pentameriformis, Spirifer----.---- ———. — — — - — - — -- — —— — --——— 63

Pentamerus magnus _———————_________———_ ———._ ————— - — ——— 55

Poulsen cited-------------------------------------------------------------- 54

phoca, Lissatrypa...--------------------- — ------------------------ — ------- 58

prognostica, Camarotoechia litchfieldensis-------------------------------- — -— 54

Gypidula coeymanensis- ———————— - ——— __________ ——— — — ___-_- 54

prunum, Atrypella........ — — —— — _._._ — — ___—_ —___ — — —— _ — _- 59

pseudopentameriformis, Spirifer (Martinial) _——————————————————— 55,63

R 

radiatus, Eospirifer____ — __-- ——— — — -------- — -- — — _---_ — — _-__ 54

reesidei, Camarotoechia------------------------------------------ 53,54,57, pi. 8

reticularis, Anomia_____-_-._-- —— _ — ———— ______ — -_-___ — —— — _-__ 63

Atrypa——...————— — — —————————- 53, 54, 58, 59, 63, pi. 8

Rhynchonellacea...———— —————— — -— — ———— -- — -- — - — -- 57

65
66 INDEX

S Page 

acheii,Atrypelltt................................................... 53,54, d8, 60, pi. 7

Lwsatrypa___________________________________ 8 

Schuchertella interstriata sinuata..._______-__.-_-____-_.... 54

shannonensis, Camarotoechia...... ______-..____...._._______ 58

shTOCki,Atrypetta............ __.______._....._____________ 54

sinuata, Schuchertella interstriata....................-___-_______... 54

Spiriferindifferns................................................_______ 61

(Martmio?) pseudopentameriformis.........._ _ - __ __..__ _. __ 55,63

modestus striatissimus....--.-_____-_..__________._-__ 54,63

pentameriformis....-... ... -

Spiriferacea_.________ 

Spinnella caetistriata...........

Stenoschisma deckerensis arctica. 

striata, Brooksina.. ______.

striatissimus, Spirifer modestus................................................ 54,63

Strophomena costulata................... —————— -—————— — -—.——— 55

Strophomenacea—-------------————..---...-._--- —— ----- — --------— 55

Strophonella euglypha......................................................... 54

swartzi, Nucleospira........................................................... 61

T 

tennis, Atrypella..................................——. —— —— 53,54,68, SB, 61, pi. 7

U 

umbonata, Ambocoelia..............-....-......----- ...--------- — ----------- 62

V 

ventricosa,Nucleospira..-------- .......------- — —— - — — _-.-.-_ — --._ —. 61

vogulicum, Conchidium___-_-.-. —.. — ------ — ------------ —— — — -.- 54,56

vogulicum krutalowskiensis, Conchidium......................-.-.. ——— -- 54,56,57

o


PLATES 7-10
PLATE 7

Figures 1—11. Atrypella tennis Kirk and Amsden, n. sp. (p. 59).

1. Brachial view of an internal mold (X2). Locality 1005, south shore Kosciusko Island; U.S.N.M. 116580.

2. 4. Anterior and pedicle views of one of the largest specimens (XI); fig. 2, pedicle valve above. Locality 1005, south 

shore Kosciusko Island; U.S.N.M. 116581.

3. 5, 6, 7. Posterior, lateral, brachial and anterior views of the holotype (X1); fig. 7, pedicle valve above. Locality 1005, 

south shore Kosciusko Island; U.S.N.M. 116579.

8. 10. Brachial and pedicle views of another individual (XI). Locality 1005, south shore Kosciusko Island; U.S.N.M. 

116582.

9. Pedicle view of an internal mold (X2). Locality 1005, south shore Kosciusko Island; U.S.N.M. 116583.

11. Oblique view of the same specimen shown in fig. 1 (X2).

12-22. Atrypella scheii (Holtedahl)? (p 58).

12. 19. Lateral and posterior (brachial valve above) views of a specimen (XI). Locality 1019, east end Heceta Island; 

U.S.N.M. 116573.

13. Pedicle view of a large specimen (XI). Locality 1589, east end Heceta Island; U.S.N.M. 116574.

14. 16, 17. Anterior, brachial and pedicle views of a specimen (XI); fig. 14, pedicle valve above. Locality 1019, east end 

Heceta Island; U.S.N.M. 116575.

15. Pedicle view of a small individual (XI). Locality 1589, east end Heceta Island; U.S.N.M. 116576. 

18, 20, 21. Posterior, brachial and lateral views of a specimen of average size (XI). Fig. 18, brachial valve above. Locality 1589, east end Heceta Island; U.S.N.M. 116577.

22. Brachial view of a specimen (XI). Locality 1019, east end Heceta Island; U.S.N.M. 116578. 

23, 30. Lissatrypa atheroidea Twenhofel (p. 58).

23. Pedicle view of an internal mold (X3).

30. Brachial view of an internal mold (X3).

Both of the above specimens are paratypes of this species that was studied and described by Dr. W. H. Twenhofel 

(1914, p. 33). They were borrowed from Peabody Museum, Yale University, through the courtesy of Professor 

C. O. Dunbar; Yale University Peabody Museum Catalogue Nos. 17715 (fig. 23), 17716 (fig. 30); Silurian, West 

Jupiter Cliffs E3, Anticosti Island. 

24—29, 31-32. Nucleospira hecetensis Kirk and Amsden, n. sp. (p. 61).

24. Brachial view (X2). Locality 2689, northeast end Heceta Island; U.S.N.M. 116587.

25. 26, 27, 29, 31. Lateral, pedicle, brachial, posterior and anterior views of the holotype (X2); in figs. 29 and 31, pedicle

valve above. Locality 2689, northeast end Heceta Island; U.S.N.M. 116586. 

28. Pedicle view of the holotype (XI).

32. Pedicle view of another specimen (X2). Locality 2689 northeast end Heceta Island; W.S.N.M. 116588. 

33-40, 47. Alaskospira dunbari Kirk and Amsden, n. gen. and n. sp. (p. 62)

33. 40. Lateral and posterior views of a specimen (X 2); in fig. 40, pedicle valve above. Locality 1005, south shore 

Kosciusko Island; U.S.N.M. 116590. Figure 40 retouched.

34. 35. Pedicle and brachial views of the holotype (X 2). Locality 1005; U.S.N.M. 116589.

36, 37, 38. Lateral, anterior, and brachial views of the same specimen (X 1); in fig. 37, pedicle valve above. Locality

1005, south shore Kosciusko Islands; U.S.N.M. 116591.

39. Pedicle view of an internal mold (X 2). Locality 1005, south shore Kosciusko Island; U.S.N.M. 116592. 

47. Enlarged surface view of a specimen showing concentric lamellae (X 6). Locality 1005; U.S.N.M. 116593. 

41. Howellella sp. (p. 63)

41. Enlarged surface view to show concentric lamellae and spines (X 6). Locality 2689, northeast end of Heceta Island;

U.S.N.M. 116601. See Plate 10, figures 7-9, for other illustrations of this species. 

42-46. Delthyrisl sp. (p. 63)

42.-46. Brachial (X 1), lateral, anterior, posterior, and pedicle (X 3) views of the same individual; in figs. 44, 45, pedicle 

valve above. Locality 1005, south shore Kosciusko Island; U.S.N.M. 116599. Figure 45 retouched.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 7

ATRYPELLA, LISSATRYPA, NTJCLEOSPIRA, ALASKOSPIRA, HOWELLELLA, AND DELTHYRIS

47
PLATE 8

Figures 1—7. Camarotoechia reesidei Kirk and Amsden, n. sp. (p. 57)

I, 2. Pedicle and lateral views of the holotype (X 3). Locality 2689, northeast end Heceta Island; U.S.N.M. 116569. 

3, 4, 5. Anterior (X 3), brachial (XI) and posterior (X 3) views of a specimen. Locality 2689, northeast end Heceta

Island; U.S.N.M. 116570. 

6, 7. Lateral and brachial views of another specimen (X 3). Locality 2689, northeast end Heceta Island; U.S.N.M.

116571. 

8-17. Atrypa cf. A. reticularis (Linnaeus), (p. 63)

8, 9, 10, 14. Pedicle, anterior, posterior, and lateral views of a specimen (X 1). Locality 2689, northeast end Heceta

Island; U.S.N.M. 116594. Fig. 8 pedicle valve above; fig. 10 brachial valve above.

II, 12. Lateral and brachial views of a small specimen (X 1). Locality 2689, northeast end Heceta Island; U.S.N.M.

116595. 

13, 16. Anterior and pedicle views of a large specimen (X 1). Locality 2689, northeast end Heceta Island; U.S.N.M.

116596. 

15. Pedicle view (XI). Locality 2689, northeast end Heceta Island; U.S.N.M. 116597.

17. Brachial view (XI). Locality 2689, northeast end of Heceta Island; U.S.N.M. 116598. 

18-22. Atrypella borealis Kirk and Amsden, n. sp. (p. 60)

18. Brachial view (X 1). Locality 1005, south shore Kosciusko Island; U.S.N.M. 116585.

19. 20, 21, 22. Lateral, anterior, posterior and pedicle views of the holotype (X 3); in fig. 20, pedicle valve above; fig. 

21, brachial valve above. Locality 1005, south shore Kosciusko Island; U.S.N.M. 116584. Figs. 19, 21 retouched. 

23-29. Conchidium alaskense Kirk and Amsden, n. sp. (p. 55).

23. Dorsal view of a young specimen (X 1). Locality 983, north shore Heceta Island; U.S.N.M. 116556.

24. Lateral view (XI). Locality 983, north shore Heceta Island; U.S.N.M. 116557.

25. Pedicle view of an immature individual (X 1). Locality 983, north shore Heceta Island; U.S.N.M. 116558.

26. 28. Anterior and pedicle views of an individual showing asymmetrical growth development (X 1); in fig. 26, pedicle 

valve above. Locality 983, north shore Heceta Island; U.S.N.M. 116559.

27. Pedicle view of an individual showing unusually coarse costae (X 1)- Locality 983, north shore Heceta Island;

U.S.N.M. 116560. 

29. Pedicle view of a rather small specimen (X 1). Locality 983, north shore Heceta Island; U.S.N.M. 116561.
GEOLOGICAL SURYEY PROFESSIONAL PAPER 233 PLATE 8

29

CAMAROTOECHIA, ATRYPA, ATRYPELLA, AND CARCHIDIUM—CONCHIDIUM
PLATE 9

Figures 1-7. Conchidium alaskense Kirk and Amsden, n. sp. All specimens illustrated on this plate from locality 983, north shore 

Heceta Island, (p. 55). 

1, 2, 6. Anterior, brachial and lateral views of a large specimen (X 1). U.S.N.M. 116562. Fig. 1 pedicle valve above.

3. Posterior view of a specimen showing asymmetrical growth development (X 1). Pedicle valve above; U.S.N.M. 

116563.

4. Lateral view of a specimen with an erect pedicle beak (X 1). U.S.N.M. 116564.

5. Anterior view (X 1); a pedicle view of this specimen is shown on Plate 10, fig. 4. Brachial valve above. U.S.N.M.

116565.

7. Interior view of a specimen which has been split longitudinally (XI). This view shows clearly the inner and outer 

plates of the brachial valve and the deep spondylium and high median septum of the pedicle valve. U.S.N.M.

116566.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 9

CONCHIDIUM ALASKENSE
PLATE 10

FIGURES 1, 5, 10, 11, 14. Conchidium alaskense Kirk and Amsdeii, n. sp. (p. 55).

I, 5, 10. Pedicle (X /z), l posterior (X J4) arid brachial (XI) views of the holotype. This is the largest specimen in the 

collections. Locality 983, north shore Heceta Island; U.S.N.M. 116567.

II. Pedicle view (XI); an anterior view of this specimen is shown on Plate 9, fig. 5. Locality 983, north shore Heceta

Island; U.S.N.M. 116565.

14. Pedicle view of a fairly large specimen (XI). Locality 983, north shore Heceta Island; U.S.N.M. 116568. 

2-4. Camarotoechia sp. (p. 58).

2, 3, 4. Brachial (X 1), pedicle (X 1.5) and anterior (XI) views of the same specimen. Fig. 4, pedicle valve above.

Locality 2689, northeast end Heceta Island; U.S.N.M. 116572.

6. Eospirifer sp. Pedicle view (X 1.5). Locality 2689, northeast end Heceta Island; U.S.N.M. 116600 (p. 63). 

7-9. Howellella sp. (p. 63).

7, 8, 9. Brachial (XI), pedicle (X 1.5) and anterior (XI) views of the same specimen; pedicle beak of this specimen 

broken. Locality 2689, northeast end Heceta Island; U.S.N.M. 116602. (See pi. 7, fig. 41, for enlarged surface 

view.) 

12, 13. Cymostrophia cf. C. costulata (Barrande). (p. 55).

12. Pedicle view (XI). Locality 2689, northeast end Heceta Island; U.S.N.M. 116554.

13. Enlarged view (X 3) of the surface of another specimen. Locality 2689. U.S.N.M. 116555.
GEOLOGICAL SFRVEY PROFESSIONAL PAPER 233 PLATE 10

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CONCHIDIUM, CAMAROTOECHIA, EOSPIRIFER, HOWELLELLA, AND CYMOSTROPHIA