The mollusca of Georgian Bay

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5 GEORGE V. SESSIONAL PAPER No. 39b A. 1915

III.
THE MOLLUSCA OF GEORGIAN BAY.
By A. D. Robertson, B.A., University of Toronto.
' (Plates X— XII)

In 1910 the writer undertook, in connection with the work of the Biological
Station, an analysis of the local molluscan fauna of Go Home Bay. This study
has since been extended to include various points around Georgian Bay, but
because of the labour involved in working over the material, this paper deals
only with the more limited area, leaving the general distribution for future dis-
cussion. The analysis of the species is believed to be fairly complete, and special
care has been taken to observe critically the specific characters and the variations,
whether due to environment, age or other cause. Notice has also been taken of
the food of the various forms and of the extent to which they themselves serve
as food for fishes and other animals.

The collections along-shore were made by hand and hand-dredges, while in
the deeper water use was made of an iron dredge, provided with a fine inner screen
supported by a course outer screen. The latter method entails much labour in
sorting over the material but gives excellent results.

In the identification of species the writer is indebted to Mr. Bryant Walker
of Detroit and to Dr. H. A. Pilsbry and Mr. E. G. Vanatta of the Philadelphia
Academy of Natural Science, who determined a number of species and confirmed
the determination of others. He is also under obligation to Professor B. A. Ben-
sley. Dr. E. M. Walker and Dr. A. G. Huntsman of the University of Toronto for
much kind assistance and advice.

The environmental features of this region are of interest because it falls within
the Archean area. A general account of these features is given elsewhere by
Bensley ('14), but reference may be made to those which are more important
from the standpoint of this paper.

1. The glaciated surface of the rock is sparingly and unevenly occupied by
soil and bottom deposits, accumulating in basins and consisting chiefly of dis-
integrated particles of gneiss, often with high organic content.

2. The indented shore-line leaves projecting headlands of fully exposed and
bare character, while the protected smaller bays form isolated swamps with usually
a deep deposit of mud and much organic material.

3 The main shore gives place outwards to larger, then to smaller islands
and finally to reefs and submerged shoals, with clear rock or boulder bottom.

4. The deeper waters of the larger bays and open waters have flat bottoms,
consisting of mud of fairly high organic content alternating with exposed patches
of the underlying rock.

96 MARINE AND FISHERIES *"

<<%lllBq- 5 GEORGE v., A. 1915

5. At places there arc open or .somewhat exposed cluiimcls with accumulations
of clean sand, almost free from orfi;anic material.

6. In addition to the wave-action on the main .shore and on the shoals, there
is a constant flow of water in and out among the islands, giving conditions of
exposure, temperature and oxygenation whicli are in marked contrast with those
of the protected bays and especially with those of the inland ponds.

In general the species of mollusca exhibit great flexibility in their environ-
mental relations. In many cases ecological selection is operative within broad
limits, while in a few the environmental type is more or less specific. The chief
factors in this selection appear to be (a) exposed or protected situation, (b) depth
of water, (c) degree of aeration, (d) character of the bottom, and (e) food conditions.
In the Genus Lymnaea, the long-spired forms occur in the stagnant bays, while
the short-spired ones inliabit rocky shores. The species of Planorbis also occur
in the swampy bays, though P. defledus extends its range to the exposed rocky
islands and the pools occurring on them. Most of the species of Physa are quite
general in their distribution, but P. integer prefers the exposed shores. The
genera Ancylus, Amnicola and Campelorna and the families Unionidae and Sphae-
riidae occur in swampy bays and also, though much less abundantly, in inland
ponds, with an extension of this range in Amnicola, the Unionidae and sometimes
Campelorna to the sandy channels and of the Sphaeriidae to these channels and to
sand or gravel banks in the deeper waters. Goniobasis is found abundantly where
there are currents of clear, well-aerated water, in sand channels, on sandy beaches
and on the exposed rocky shores. The genus Valvata is a sand-loving one, although
of the two species, one, tricarinata is also found plentifully in weedy, muddy bays.

The inland ponds are exposed to extremes of summer and winter temperature.
They are limited in the facilities they afford for migration to the deeper waters.
They are poorly provided with means of aeration and are often surfeited with
decaying vegetation and so afford an environment not highly favorable to mollus-
can life. Few forms occur and these not abundantly. Among them are Ancylus
parallelus, Campelorna decisum, Amnicola limosa and the Sphaeriidae.

The protected muddy bays where these conditions are reversed afford a rich
molluscan fauna with a wide range of species which includes the Unionidae, the
Sphaeriidae, the genera Valvata, Avmicola, Goniobasis, Planorbis, Ancijlus, Physa
(with the exception of P. integer niagarensis) and the long-spired species of Lym-
naea {palustris, columella and lialdemani).

In the weedy sand-runs the same forms occur, wath the exception of Planorbis
exactions, P. dilatatus and the Lymnaea mentioned above. In clean sand channels,
free from weeds and exposed to currents, the Unionidae, the Sphaeriidae and
the genera Campelorna, Valvata and Goniobasis occur.

The exposed rocky shores which seem to afford a scanty supply of food and an
abundance of well-aerated water, 3aeld Lymnaea emarginata canadensis, L. decollata,
L. stagnalis sanctamariae, Planorbis deflectus and the various species of the Physa.

In the shallow island pools which are well-aerated and have a good supply
of food, but which, on the other hand are subjected in some cases to destruction
by drought and to severe winter conditions, Planorbis deflectus and Lymnaea
palustris abound.

I ' THE MOLLUSC A OF GEORGIAN BAY 97

r

oESSIONAL PAPER No. 39b

In deep dredging from sandy or gravelly bottoms, the Sphaeriidae and the
genus Valvata are obtained.

The total number of species identified is 37, representing 14 genera in 8 families,
as follows: —

I. Family lymnaeidae.

A. Genus Lymnaea.

1. Lymnaea stagnalis sanctamariae, Walker.

2. Lymnaea (Galba) decollata, Mighels.

3. Lymnaea (Galba) emarginata canadensis, Sowb.

4. Lymnaea (Galba) palustris, Muller.

5. Lymnaea (Pseudosuccinea) columella, Say.

6. Lymnaea (Acella) haldemani, (Deshayes) Binney.

B. Genus Flanorbis.

7. Planorbis (Helisoma) hicarinatus. Say.

8. Planorbis (Pierosoma) trivolvis, Say.

9. Planorbis (Planorbella) campanulatus , Say.

10. Planorbis (Menetus) exacuous. Say.

11. Planorbis, (Menetus) dilatatus, Gould.

12. Planorbis (Gyraulus) hirsutus, Gould.

13. Planorbis (Gyraulus) deflectus, Say.

II. Family physidae.

C. Genus Physa.

14. Physa heterostropha. Say.

15. Physa ancillaria, Say.
15a. Physa ancillaria tnagnalacustris , Walker.
15b. Physa ancillaria vinosa, Gould.

16. Physa gyrina, Say.

17. Physa integer niagarensis, Lea.

D. Genus Ancylus.

18. Ancylus parallelus, Hald.

III. Family streptomatidae.

E. Genus Goniobasis.

19. Goniobasis livescens, Menke.

20. Goniobasis haldemani, Tryon,

IV. Family amnicolidae,

F. Genus Amnicola.

21. Amnicola limosa, Say.

22. Amnicola em,arginata, Kiister.

23. Amnicola lustrica, Say.

V. Family valvatidae.

G. Genus Valvata.

24. Valvata tricarinnta. Say.

25. Valvata sincera, Say.

VI. Family viviparidae.
H. Genus Campeloma.

26. Campeloma decisum, Say.
39&— 7 II

98 MAUL\'K AXD FISH i:h'Ii:S i

5 GEORGE v., A. 1915

VII. F:.mily unionidae.
I. (lonus Lampsilis.

27. Lampsilis venlricosus, Barnes.

28. Laiiipsilis lutcolis, Lamarck.

28:i. Lampsilis lutcolis rosaccus De Kay.
J. Genus Anodonta.

29. Anodonta grandis, Say.

29a. Anodonta grandis footiana, Lea.
K. Genus Anodontoides.

30. Anodontoides ferussacianus, Lea.
L. Geuns Unio.

31. Unio complanatus, Solander.

VIII. Family sphaeriidae.
M. Genus Sphaerium.

32. Shpaerium simile, Say.

33. Sphaeriiwi siriatinum, Prime.

34. Sphaerium rhomhoideuyn, Say.

35. Sphaerium (Musculium) securis, Prime.

36. Sphaerium (Musculium) partumeium, Say.
N. Genus Pisidium.

37. Pisidium abditum, Hald.

• Family lymnaeidae.

Represented by 13 species of Lymnea and Planorbis, together forming the third
of the total number of Molluscan species.

Genus Lymnaea.

Of six species identified, two, L. emarginata canadensis and L. Palustris are the
prevailing types. Both occur abundantlj^ L. haldemani was taken in only two
situations, although it was present in numbers L. decollata was taken in several
places, but nowhere abundantl3^ Of L. stagnalis sanctaemariae only six specimens
in all were obtained. L. columella was frequently found, but not in numbers.

L. stagnalis sanctaemariae, Walker. The six specimens were identified as this
species and variety by Mr. E. G. Vanatta. The shortened spire corresponds to
the exposed situation in bare rocky channels. A light colored, transparent shell,
5 to 5^ rounded whorls with distinct suture. The aperture is broadly ovate, the
edge of the lip thin, flared anteriorly; slit-like umbilicus widely open or nearly
closed by the callus. (PI. XI, Fig. 18).

L. (Galba) decollata, Mighels, occurs on rocky shores and in shallow rocky
bays of outer islands. Stout, nicely formed little shell, rhomboidal in outline
when viewed facing the aperture. Large body whorl, expanded aperture and short,
sharp spire. Whorls 3. Color brownish horn, tinged with green, apical whorls
darker, white varical thickenings on body whorl. In comparison with L. emargi-

THE MOLLUSC A OF GEORGLAN BAY 99

SESSIONAL PAPER No. 39b

nata canadensis the shell is smaller, shorter and smoother, the whorls fewer and
more convex and the sutures are more impressed. (PI. X, Fig. 7).

L. emarginata canadensis. Sowb. ; very abundant on cleanrocky shores, especially
of the outer islands. Found also on sand and pebble bottom. Corresponding to
its exposed position and in contrast to the other species, L. palustris, it is thick-
shelled with shortened spire and is of light coloration. It is a medium-sized species
(adult length 20-25mm.) and is usually recognized easily by its light horn colour
and malleated surface. The spire is shorter than the aperture, the whorls well-
rounded, 5-6 and the sutures distinct. The aperture is large and ovate with a
somewhat flaring lip and with reddish varical thickenings usually prominent im-
mediately behind it. A white callus spreads over the body-whorl and covers but
does not close the deep slit-like umbilicus. Usually with several whitish or reddish
varical thickenings. Identified as this variety by Mr. E. G. Vanatta. As it occurs
at Go Home it is quite variable, especially in surface malleation, thickness of the
shell, height of the whorls and length of the spire. Thinner shells show more definite
malleations. Its food consists of algae. It has been taken from the stomach of
the whitefish, Coregonus clupeiformis. (PL X, Fig. 14).

L. (Galba) palustris, Muller, abundant in shallow bays on the bottom or on
submerged vegetation, often on mud flats above the water's edge. It prefers
moderately high temperatures. It is easily recognized by its narrow elongated
form, dark colour and by the aperture which is usually shorter than the spire.
Lip somewhat flared. Surface of shell variable, smoother in island pools, usually
roughened by coarse lines of growth in muddy bays. Sometimes malleated.
Color brown to almost black, darker in pools, often whitish due to erosion. In
young, color darker and lip not flared. Distinguishable from L. emarginata
canadensis in the more slender elongated form, narrower and shorter aperture,
longer spire, darker color and distinct habitat. It feeds upon the filamentous
green algse, diatoms and desmids. Found in the stomachs of whitefish. (Pi. X, Fig. 8) .

L. (Pseudosuccinea) columella, Say. Common on lower surface of lily-leaves
in stagnant, muddy bays. Easily recognized by its expanded and oblique body
whorl, its long aperture, expanded anteriorly, rather sharp-pointed spire and its
delicate shell-structure. Lines of growth prominent. Its elongated form and es-
pecially its delicate shell are adaptations to its protected habitat. Food consists
of diatoms, desmids and other green algse. (PI. XI, Fig. L5).

L. (Acella) haldemani (Deshayes) Binney: Found on the lower surface of lily-
leaves in well-sheltered muddy bays in late summer. Observed in but two situa-
tions, both of which were removed from open water and were especially well-pro-
tected. Several specimens secured in each situation. Diligent search failed to
reveal any during the early summer and nothing was found to indicate their habitat
during this period. These observations agree in their main features with Kirk-
land's account as given by Baker ('11). Those secured were, however, considerably
removed from deep water; none were observed in the approaches to the bays,
neither were any secured in dredging. This is the most striking Lymnaea of the
region. Its extremely slender form, long spire, oblique, flattened whorls, long
nan-ow aperture, sharply angular at the posterior end and its thin transparent
396—71 II

100 MAIilXK AXD FISHERIES

5 GEORGE v., A. 1915

shell are unmistakable characters. The long spire and delicate shells are in conform-
ity with its protected habitat. It varies in length of spire, conxevity of whorls
and size and shape of the aperture and the axis is often considerably twisted. Its
food consists of algir. (PI. X, Fig. 4).

Genus Planorbis.

Seven species were identified. Of these, three, P. bicarinatus, P. trivolvis and
P. car7}pa7iulatus belonging to a large-shelled group inliabiting muddy bays, possess
comparatively high, sinistral shells and certain common characters in respect of
the reproductive organs which will be dealt with in a subsequent paper. The
others belonging to a small-shelled group with a more varied habitat possess low,
flattened, dextral shells and, as far as examined, certain other characters in the
reproductive -organs. This group includes P. hirsutus, defiectus, exacuous and
dilatus, the range of distribution of which varies with each species.

Planorbis bicarinatus, Say, occurs abundantly in weedy sand runs and weedy
muddy bays; found also on rocks near the latter. Distinct and easily recognized
by the two prominent angular carinae. Aperture slightly oblique, somewhat
triangular, broadly rounded below, lip thin with varical thickening behind. Shell
bi-concave, lower concavity with the sides interrupted by the carinae, upper smooth
and funnel-like. Former apertures often evident on the body whorl as pronounced
transverse ridges with darker periostracum. The possession of a broad high shell,
which is carried on edge and has an aperture only slightly oblique, doubtless in-
dicates for this form sheltered rather than exposed situations. In the young the
carinae as pronounced but the aperture less oblique than in the adult. Food con-
sists of green algse. (PI. X, Fig. 5).

Planorbis trivolvis, Say. ; found plentifully in protected muddy bays and some-
times along the sheltered shores of the inner islands. Prefers shallow bays with
comparatively high temperature. Found onlj^ in shore collections and water less
than 2 feet in depth. The largest Planorbis of the region (Adult measurements, —
width 20-30 mm, length 10-13 mm). Shell with shallow concavity above the
smooth slopes of which are interrupted by the carina of about the last half of the
body whorl. A deep umbilicus into which the rounded whorls disappear below.
Aperture large, triangular or rhomboidal in outline, narrower above, lip thin,
much flared Mith a varical thickening behind. One or more former apertures
evident. Lines of growth coarse. Not fitted for exposed situations because of
the size and shape of the shell and the vertical position in which it is carried. Varies
with age. Young lighter in color, shells high and narrow, while adults are much
broader than high. Recognized easily at all stages by the upper concavity of the
shell. Series showing all stages readily secured. Eggs laid in flat brownish capsules
on lily-leaves, sticks and even on other molluscs. Food, filamentous algse, diatoms
and desmids. (PI. X, Fig. 6).

Planorbis campamdatus, Say. ; occurs abundantly in weedy places, both muddy
and sandy, up to the depth of at least three fathoms. Easily recognized by the
campanulate expansion of the body whorl a short distance behind the aperture and

THE MOLLUSC A OF GEORGIAN BAY 101

SESSIONAL PAPER No. 39b

the narrowly constricted throat just behind this. Aperture rhomboidal, narrowed
above. Narrowly rounded tops of the whorls all in the same plane. Lower surface
like trivolvis but narrow lower edge of the whorls more rounded and less angular.
Lines of growth coarse, regular and parallel. Adapted in the same manner as the
two preceding species to protected rather than exposed situations. Often distorted
so that the tops of the whorls are inclined at various angles. Varies considerably
in length of campanulate expansion and also in thickness of shell. Feeds on fil-
amentous green algie, diatoms and desmids. (PI. X, Fig. 1).

Planorhis exacuous, Say.; occurs in protected weedy places, never in large
numbers. A well-marked species, having as distinguishing features a very sharp
peripheral carina, a lens-shaped shell and small size. Whorls flattened above,
broadly rounded below. Aperture triangular and very oblique. The greatly
flattened shell and very oblique aperture which allow it to lie close to the surface
over which it crawls would seem to adapt it to an exposed habitat, yet it was found
only in protected places. Varies in color, light coloured in sandy, and brown in
muddy places. (PL X, Fig. 3).

Planorhis dilatatus, Gould, occurs on sticks along muddy river banks and in
muddy bays. Only a few obtained. Small brownish; top of shell flat; sharp
peripheral keel almost level with top of shell; whorls broadly rounded below;
aperture oblique; compared with P. exacuous it is smaller and higher in propor-
tion, the whorls are flatter above and much more convex below and the carina is
placed much higher.

Planorhis hirsutus, Gould, occurs plentifully in weedy, sandy channels and in
muddy bays or in channels on smooth rocks covered with light deposit of sediment.
Easily recognized by the rough hairy shell. Shell wide and flat, having a sharp,
strongly deflected peripheral keel and a very oblique aperture. Surface covered
by crowded rows of hairs. Last portion of body whorl often strongly deflected.
Shell varies greatly with age. A shell of about three and a half whorls is concave
above and below, the aperture is only slightly oblique, the centrally-placed peri-
pheral keel is just appearing behind the aperture, the shell is high and all the whorls
are on the same level. In older shells the aperture becomes oblique, the shell be-
comes wide and flat, and there is a pronounced peripheral keel deflected down-
wards. The last whorls also drop below the level of the preceding whorls and the
shell becomes saucer-shaped. (PI. X, Fig. 2).

Planorhis deflectus, Say, the most abundant Planorhis species of the region,
possesses a wider range of habitat than any other species, plentiful in quiet weedy
bays, in weedy sand channels and in shallow dark-colored pools on islands. Occurs
also on exposed shores. Recognized by its small size and rounded periphery.
Aperture only slightly oblique. Color varies from yellowish on lily-leaves in bays
to dark brown in dark island pools. Whorls in one plane or with last part of body-
whorl deflected downwards. Periphery sometimes flattened on its upper edge,
giving a peculiar sloping aspect to last whorl. Some specimens banded alternate
white and dark brown.

102 MARINE AND FISHERIES

5 GEORGE v., A. 1915
Family imiysidae.

Represented by six si)ecic.s belonging to two genera, Physa and Ancylus.

Genus Physa.

Of this genus five species were obtained. Four of these are large and dark-
colored, have short spires, thin shells and indistinct sutures and occur throughout
a wide range of habitat. The fifth is small, light colored, with white varical thick-
enings of the whorls, has a more elongate spire and is found only on semi-exposed
rocks. Although the two groups are quite distinct, the species within the first
group are not so clearly differentiated. The characters upon which the species of
this genus are based are exceedingly variable and the extremes of variation grade
into one another so smoothly that an attempt to verify the present classification
by breeding experiments and anatomical investigation seems desirable. The writer
intends to undertake the task in the near future. In the meantime the distinctions
here used will be those of the literature of the genus.

Physa heterostropha, Say, occurs usually in protected situations in weedy bays
or quiet rocky channels, rare. Surface smooth and shiny, without sculpture, the
spire elevated and the sutures distinct. Food, diatoms, desmids and other algaj.

Physa ancillaria, Say, very abundant, almost everywhere in sheltered bays
and along partially exposed shores. In the spring it may be seen collecting in vast
numbers to the breeding-grounds in rocky channels and in the bays of rocky islands.
Within a few days after copulation the eggs are laid in elongated capsules. A
single individual may lay as many as five capsules containing in all 150-300 eggs.
Spire short, sutures not so distinct as in P. heterostropha. Shell more robust than
in that species. Surface smooth and shining, sculptured. Varies much in surface
sculpture, height of spire, size and shape of aperture and number of digitations on
mantle. Such malformations as forked tentacles and lobes arising from upper sur-
faces of foot were found. Food consists of diatoms, desmids and other green algae.
A number were found in whitefish stomachs. (PI. XI, Fig. 19).

A variety, magnalacustris, Walker, with white lines on body whorl also occurs.

The variety vinosa occurs in sheltered bays and on partially exposed shores.
Shell robust, spire short but sharp; whorls rounded and suture distinct.

Physa gyrina, Say. Not very abundant, found in sheltered bays. Differs
from P. ancillaria in larger size, more elevated spire, more slender form and coarser
surface sculpture.

Physa integer niagarensis, Lea; found on somewhat exposed rocky shores.
much smaller than any of previous forms, shell much like a small reversed L.
emarginata canadensis. Shell light horn with many white bands transverse to
whorls. Shell heavy, spire elevated, apex sharp, sutures distinct and whorls
rounded. Identified by Dr. Pilsbry.

\

{

THE MOLLUSC A OF GEORGIAN BAY 103

SESSIONAL PAPER No. 39b

Genus Ancylus.

Ancylus is represented by a single species.

Ancylus parallelus, Hald.; very common in sheltered bays on under sides of
lily leaves and on sticks. Shell flat, pyramidal; apex ^ length of shell from posterior
end, directed backwards and to the left; sides nearly parallel, shell narrower in
front. (PI. XI, Fig. 17).

Family streptomatidae.

Represented by two (?) species of the Genus Goniobasis.

Genus Goniobasis.

Goniobasis livescens, Menke. Obtained abundantly where there are currents,
in sand runs or along rocky shores and on the rocky shoals near the outer islands.
Occurs also but not plentifully in muddy bays. Spire long and tapering, apex
usually eroded away, whorls 8-9, flattened, suture not deeply impressed, distinct
carina at lower edge of whorl. Aperture small and rhomboidal; prolonged ante-
riorly into a slight groove, closed by an operculum borne on upper side of foot.
Unlike the long spired species of Lymnaea which inhabit sheltered situations, this
form which is also long spired is well-adapted to exposed places because of its
strong heavy shell. In contrast with the Lymnaea also, it, when detached, does
not float on the water, but sinks at once into deeper water. A quite variable
species. Varies in length and stoutness of spire, usually high and slender, often
quite short and stout, color dark brown, shaded with green, light green or white.
In young, carina well-marked; in adults, no carina on body whorls; in younger,
color much darker. Feeds on diatoms and desmids. (PI. XI, Fig. 16).

Goniobasis haldemani, Try on; (not positively identified.) Occurred on shady
beach along exposed shore. Few obtained. More slender and elongated, whorls
more rounded than in livescens. No carina and the color white tinged with green.

Family amnicolidae.

Represented by three species, all belonging to the genus Amnicola.

Genus Amnicola.

Of the three species obtained here, A. limosa is the most abundant. All
occur in weedy places either with mud or sand bottom. A. limosa is secured
also on the rocky shores of even the outer islands and A. limosa and lustrica were
obtained in deep dredgings. Operculate.

Amnicola limosa, Say; obtained on weeds in sand channels or muddy bays,
on rocky shores and in dredging at 20 fathoms or more. Very abundant, tentacles
long and constantly in motion. The jet-black eyes placed at outer bases of ten-

104 MARINE AND FISHERIES

5 GEORGE v., A. 1915

tacles. Shell globose, whorls convex, apex usually rounded. Umbilicus small,
aperture rounded. Shows considerable variation. Shell may be conic, spire
elongated and apex sharp. The sutures vary in distinctness. Eggs laid in small
triangular capsules on weeds, sticks, stones and even on the shells of other
molluscs. (PI. X, Fig. 9).

Amnicola emarginata, Say. Not numerous. Found with A. limosa. Dis-
tinguished from it by the truncated apex, the first whorl not rising above the
second. Spire also more elongated than usual in A. limosa.

Amnicola liistrica,Ssiy; not abundant. Occurs with other species of Amnicola;
dredged in 20 fathoms or more of water. Compared with A. limosa, shell thinner,
spire much more elevated, apex sharp, body whorl scarcely larger than the pre-
ceding one. (PI. X, Fig. 10).

Family valvatidae.

Two species belonging to one genus occur.

Genus Valvata.

Of the two species, one, V. tricarinata occurs abundantly. Operculate. The
plume-like gills borne within the mantle-cavity.

Valvata tricarinata, Say., abundant in weedy places among islands on either
sandy or muddy bottoms. Occurs on sandy bottoms even to depth of 20 fath-
oms. Prominent carinae, usually three. Umbilicus broad, open to apex. Whorls
loosely appressed. Quite variable. One or all of the carinae may be lacking or
indistinct. The order of their reduction appears to be peripheral, lower, upper.
In sandy places malformations in which whorls do not touch preceding whorls
occur, seen in early whorls, body whorl or intermediate ones. Found in white-
fish stomachs. (PI. XI, Fig. 21).

Valvata sincera. Say. Found only in dredgings in sandy places. Occurs
at depths of up to 20 fathoms. Not abundant. Compared with V. tricarinata
there are no carinae and whorls are more rounded. There are distinct, sharp,
elevated ridges, parallel to lines of growth. In the young these ridges are finer
and more closely placed. Subject in sandy places to malformations similar to
those occurring in V. tricarinata. Abundant in stomachs of whitefish. (Pi. XI,
Fig. 22).

Family viviparidae.

Represented by one species belonging to Genus Campeloma.

Genus Campeloma.

Operculate. As family name indicates young are produced alive.
Campeloma decisum. Say; occurs abundantly in sheltered bays with soft
mud bottoms and in sand channels with decaying vegetable content. Congre-

THE MOLLUSC A OF GEORGIAN BAY 105

SESSIONAL PAPER No. 39b

gates in decaying lily stems and on decaying logs. Recognized easily by large,
heavy greenish shell, with short spire and eroded apex, its large, broad, brownish
mottled foot and its long tapering tentacles. Color varied by narrow, irregularly
placed dark bands crossing the whorls. In dark water it is often rusty brown.
Young lighter in colour, lip of aperture thinner and shell has numerous fine lines
parallel to whorls. All stages of development from young in the uterus to the
adult form are easily obtained. Feeds on decaying vegetable matter. (PI. XI,
Fig. 20).

Family unionidae.

Represented by seven species belonging to four genera.

Genus Lampsilis.

Two species of this genus are reported.

Lampsilis ventricosus, Barnes. The single specimen obtained some years ago
was identified by Bryant Walker as L. ventricosus canadensis, Lea, conforms to de-
scriptions of L. ventricosus and since Simpson (1900) includes canadensis in synon-
ymy of ventricosus it is here designated by the latter name. Shell, thick; color
yellowish, darker in front. Few faint broad radiations behind, lines of growth
coarse, beaks eroded, hinge line straight, nacre white, cardinal teeth double in
both valves, lateral teeth single in right valve, double in left.

Lampsilis luteolis, Lamarck. Very abundant on the slopes of deep pools in
sandy channels and along sloping muddy shores. Shell much higher behind the
beaks. Beak sculpture consisting of about 13 fine wavy concentric ridges. Color
light or dark brown, usually with numerous, sometimes brilliant narrow green
rays. Two cardinal teeth in each valve, lateral teeth double in left valve and
single in the right, long, curved and lamelliform. Nacre white. Hinge line curved.
Varies in periostracum which may be smooth and shining or coarsely wrinkled,
in outline of shell, in color in prominence and number of rays and in cardinal
teeth which are pyramidal or lamelliform. Females inflated posteriorly. Young
narrower than adults, A form is common here which is large and heavily shelled,
has a dark brown periostracum often with a greenish sheen towards the umbones
and is coarsely and closely wrinkled at the margin of the gape. The variety
rosaceus which has smooth reddish-brown periostracum and rosy nacre also occurs.
(PL XII, Figs. 23, 26,30).

Genus Anodonta.

Of this genus one species occurs.

Anodonta grandis, Say, occurs plentifully on steep slopes of sand banks in
sandy channels, and also, but less abundantly in the soft mud of sheltered bays.
Shell thin, smooth, inflated, hinge-teeth lacking, usually dull in colour. Beak
sculpture, four or five concentric ridges with anterior and posterior loops. Varies
greatly in color, sometimes dull and almost rayless; at times brilliant, with many
green rays. Varies also in inflation of shell and in outline. Forms were found
typical of footiana as well as other typical of grandis, s,s,, but there were also
many intermediates, (PI, XII, Figs. 25, 28),

I

\

106 MARINE AND FISHERIES

5 GEORGE v., A. 1915
Genus Anodontoides.

Represented by a single species.

Anodontoides fer It ssacianus, Lea. Plentiful in shallow sand channels and also
in muddy places. Compared with A. grandis is smaller and much more elongated.
Fine radiating sculpture at posterior of beak in addition to the five or six concen-
tric doubly looped ridges. Color brown, tinged with green anteriorly and below
and rusty brown posteriorly and above. (PI. XII, Fig. 27) .

Genus Unio.

Of this genus also only a single species occurs.

Unio complanatus, Solander. Ver}^ abundant in sand channels and along
muddy or sandy shores of the inner islands or bays. Shells dark brown, no rays,
beaks eroded, placed well forward, height behind beaks not greatly exceeding that
in front, anterior end rounded, posterior tends to be angled. Ventral margin and
hinge margin nearly straight, margin behind hinge curved. Teeth, both cardinal
and lateral, single in right and double in left valve. Very variable, shells, narrow
or broad, light or heavy; nacre white or purple. In old shells ventral margin tends
to become emarginate. (PI. XII, Fig. 29).

Family sphaeriidae.

There are of this family, in this region, six species belonging to the two genera,
Sphaerium and Pisidium.

Genera Sphaerium.

Five of the six species mentioned above belong to this genus.

Sphaerium simile, Say, occurs abundantly, buried in the sand on the slopes of
deep pools in sandy channels; occurs also in the mud of sheltered bays. The
largest of the family in this district. Beaks nearer anterior end of shell, inflated,
closely approximated, beaks marked with coarse lines, lines of growth heavy,
regular. Color brown or yellow, often brown with yellow border. Hinge line
curved. Hinge slight. Varies in color. Young usually yellow, adult usually dark.
Young thin, adult somewhat inflated. (PI. I, Fig. 11).

Sphaerium striatinum, Lamarck. Abundant in sand banks in channels and in
mud in sheltered bays. Shell somewhat inequilateral, beaks full, separated, lines
of growth coarse with finer lines between. Beak sculpture not uniform, numerous
regular coarse lines, few coarse lines irregularly placed or beak smooth. Shell thin,
nacre bluish white with purple bands or patches.

Sphaerium rhomboideum, Say. Sand banks and muddy bays. Shell equi-
lateral. Umbones depressed, approximated, marked by fine lines, lines of growth
rather fine, regular; anterior slightly truncated, posterior somewhat angled below.
Dark brown, narrow yellow border around margin; nacre bluish white. (PI. X,
Fig. 12).

THE MOLLUSC A OF GEORGIAN BAY 107

SESSIONAL PAPER No. 39b

Sphaerium {Musculium) securis, Prime. Abundant in sandy channels. Small,
fragile, much higher in front of umbones which are centrally placed. Truncated
behind, rounded in front, rhomboidal in outline, umbones calyculate and inflated,
marked by fine concentric lines; lines of growth fine. Found in stomachs of white-
fish. (PI. X, Fig. 13).

Sphaerium (Musculium) partumeium, Say. Identified by Mr. E. G. Vanatta.
Sand channels. Shell equilateral, oval in outline, large, truncated behind, color
yellow, lines of growth fine.

Genus Pisidium.

One species of this genus occurs here.

Pisidium virginicum, Bourguignat. Abundant in sandy channels. Dark
colored. Umbones elevated, placed posteriorly, shell heavy, brown or yellowish,
truncated behind, triangular in front. Lines of growth coarse. Cardinal teeth
single in right valve, inverted V-shaped; double in left; oblique, anterior narrow,
posterior stout, inclined tow^ards pyramidal. Laterals stout, double in right valve,
single in left.

ARTIFICIAL KEY TO THE SPECIES IN THIS REPORT.

Since the recognition of these species is not an easy matter the following key
based upon shell characters is given to facilitate their identification.
A. 1. Univalve, shell consisting of one valve.

B. 1. Non-operculate, no operculum borne on upper surface of foot and
closing the aperture of shell when animal is retraced.
C. 1. Spire elevated and dextral, or flat.
Family lymnaeidae.
D. 1. Spire elevated and dextral.
Genus Lymnaea.
E. 1. Spire elongated.

F. 1. Much elongated and slender, whorls very oblique, shell thin.

Lymnaea haldemani.
F. 2. Elongated but stout; dark colored.
Lymnaea palustris.
E. 2. Spire short.

F. 3. Thin-shelled, body whorl very large, whorls very oblique.
Length of shell 15-18 mm.
Lymnaea columella.
F. 4. Shell large, smooth; whorls 5; length of shell 25-30 mm.

Lymnaea stagnalis sanctaemarioe.
F. 5. Shell medium sized, usually malleated; whorls 5; length of
shell 20-25 mm.
Lymnaea emarginata candensis.
F. 6 — Shell small, smooth; whorls 3; length of shell 10-12 mm.
Lymnaea decollata.

108 MARINE AND FISHERIES

5 GEORGE v., A. 1915

D. 2. Spire Hat.

Genus Planorbis.
E. 3. Shell large, high and sinistral.
F. 7. With wide shell concavity above.

Planorbis trivolvis.
F. 8. With narrow deep concavity above, two carinas.

Planornis bicarinatus,
F. 9. With no concavity above. Expansion behind the aperture.
Planorbis campanulatus.
E. 4. Shell small, depressed and dextral.
F. 10. Shell covered with bristles.

Planorbis hirsutus.
F. 11. No bristles on shell.

G. 1. Peripheral keel level with the top of shell.

Planorbis dilatatus.
G. 2. Peripheral keel centrally placed. Shell lens-shaped.

Planorbis exacuous.
G. 3. No peripheral keel.

Planorbis deflectus.
C. 2. Spire elevated and sinistral or shell not spiral.
Family physidae.
D. 2. Spire elevated and sinstral.
Genus Physa.
E. 5. Shell large.

F. 12. No sculpture on surface of shell.

Physa hetei'ostropha.
F. 13. Surface sculptured, spire short, suture not impressed.

Physa ancillaria.
F. 14. Surface sculptured, spire more elevated, sutures impressed.
Physa gyrina.
E. 6. Shell small, usually whitish.
Physa integer niagarensis.
D. 4. Shell not spiral.
Genus Ancylus.

Ancylus parallelus.
B. 2. Operculate, operculum borne on the upper surface of foot and
closing the aperture of the shell when the animal is retracted.
C. 3. Spire very high, shell large, length 25-30 mm.'
Family streptomatidae.
D. 5. Whorls towards apex not rounded.

Goniobasis livescens.
D. 6. Whorls towards apex more or less rounded.
Goniobasis haldemani.
C. 4. Spire low or only moderately high.
D. 7. Umbilicus narrow.

THE MOLLUSC A OF GEORGIAN BAY 109

SESSIONAL PAPER No. 39b

E. 7. Shell small, about 5 mm. in length.
Family amnicolidae.

F. 15. Shell globoid or low conic; apex rounded.

Amnicola limosa.
F. 16. Shell low, conic, apex emarginate.

Amnicola emarginata.
F. 17. Shell high conic, apex sharp.
Amnicola lustrica.
E. 8. Shell large and heavy. Apex usually eroded.
Family viviparida.

Campeloma decisum.
D. 8. Umbilicus wide.
Family valvatidae.
E. 9. Whorls bearing three carinae.
Valvata tricarinata.
F. 10. Whorls without carinae.
Valvata sincera.
A. 2. Bivalve shell consisting of two valves, united by a dorsal hinge.
B. 3. Shell large, one set of cardinal teeth in each valve.
Family unionidae.
C. 5. Shell heavy, bearing hinge teeth.

D. 9. Height behind beaks not greatly in excess of that in front.
Genus Lampsilis.
E. 11. Rays numerous and narrow.

Lampsilis luteolis.
E. 12. Rays few and broad.

Lampsilis ventricosus.
C. 6. Shell light, no hinge teeth.
Genus Anodonta.
D. 11. Shell high, no radiating sculpture on posterior part of beak.

Anodonta grandis.
D. 12. Shell low, elongated, radiating sculpture on posterior of beak.
Anodontoides ferussacianus.
B. 4. Shell small, two sets of cardinal teeth in each valve.
Family sphaeridae
C. 7. Not trigonal in outline.
Genus Sphaerium.
D. 13. Beak not calyculate.

E. 13. Lines of growth regular, coarse.

F. 19. Shell usually with definite narrow yellow border and rhombic
outline.
Sphaerium rhomhoideum.
F. 20. Shell without definite yellow border and oval in outline.
Sphaerium simile.

110 MARINE AND FISHERIES

5 GEORGE v., A. 1915

E. 14. Lines of growth not regular, coarse, with numerous fine
between.

Sphaerium striatinum.
D. 14. Beaks calyculate.

E. 15. Rhomboidal in outline.

Sphaerium {Musculium) partumeium.
C. 8. Shell trigonal in outline
Genus Pisidium.

Pisidium virginicum.

LIST OF ARTICLES CONSULTED IN THE DETERMINATION OF THE FOREGOING

SPECIES.

1898. Baker, F. C. — The Mollusca of the Chicago Area. The Chicago Academy of Sciences, (Natu-
ral History Survey) ; Bulletin No. Ill, Pt. I. 1898.

1902. Baker, F. C— The Mollusca of the Chicago Area, The Chicago Academy of Sciences, (Natural
History Survey) ; Bulletin No. Ill, Pt. II. 1902.

1911. Baker, F. C. — The Lymnseidae of North and Middle America. The Chicago Academy
of Sciences: -Special Publication No. 3, 1911.

1865. BiNNEY, W. G. — Land and Fresh-water Shells of North America, Pts. II and III. Smith-
sonian Miscellaneous Collections: (143, 144) vol. VII, 1867.

1870. BiNNEY, W. G.— Report of the Invertebrata of Massachusetts (A. A. Gould, edited by
Binney) Boston, 1870.

1901. Crandall, O. a. — The American Physse, Nautilus, 1901.

1905. Dall, W. H. — Land and Fresh- water MoUusks. Harriman Alaska Expedition, vol. XIII,
New York, 1905.

1882. Latchford, F. R. — Notes on the Ottawa Unionidse, Transactions Ottawa Field Naturalists'
Club, No. 3, Ottawa, 1881-82.

1865. Prime, T. — Monograph of American Corbiculidae. Smithsonian Miscellaneous Colleciiunc.
(145) vol. VII, 1867.

1858. Say, T.— The Complete Writings of Thos. Say on the Conchology of the United States.
Edited by W. G. Binney, New York, 1858.

1900. Simpson, Chas. T. — Synopsis of the Naiades or Pearly Fresh- Water Mussels. Proceedings
of the U. S. National Museum: vol. XXII, Washington, 1900.

1873. Tryon, G. W., Jr.— Land and Fresh-water Shells of North America, Pt. IV, Smith-
sonian Miscellaneous Collections (253) vol. 16; Washington 1873.

1

THE MOLLUSCA OF GEORGIAN BAY III

SESSIONAL PAPER No. 39b

EXPLANATION OF PLATES.

/ PLATE X.

}. Planorbis campanulatus, Say, x2i.
J. Planorbis hirsutus, Gould, x3.

3. Planorbis exacuous, Say, x3.

4. Lymnsea haldemani, (Deshayes) Binney, x3.

5. Planorbis bicarinatus. Say, x2.

6. Planorbis trivolvis, Say, xlj.

7. Lymnsea decollata, Mighels, x3.

8. Lymnsea palustris, MuUer, x2.

9. Amnicola limosa. Say, xl^.
10. Amnicola lustrica, Say, xl^.

IL Sphserium simile, Lamarck, xH. '

12. Sphserium rhomboideum, Say, xl h.

13. Sphserium (Musculium) securis. Prime, x3.

PLATE XI.

14. Lymnsea emarginata canadensis, Sowb, x2.

15. Lymnsea columella. Say, x3.

16. Goniobasis livescens, Menke, x2.

17. Ancyliis parallelus, Hald, x3.

18. Lymnsea stagnalis sanctaemariae, Walker, x2.

19. Physa ancillaria. Say, x3|.

20. Campeloma decisum, Say, xl^.

21. Valvata tricarinata. Say, 3^.

22. Valvata sincera. Say, 3^.

PLATE XII.

23. Lampsilis luteolis, Lamarck, x|. .

24. Series, lamellar to pyramidal teeth in Lampsilis luteolis, Lamarck, xj.

25. Anodonta grandis, Say, xf.

26. Lampsilis luteolis, Lamarck, xf.

27. Anodontoides ferussacianus, Lea, xf .

28. Anodonta grandis, Say, x|.

'29. Unio complanatus, Solander, xf .
30. Lampsilis luteolis, Lamarck, xf .

A

Plate X

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17

20

21

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Plate XII

27

23

24

28

26

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BIOL OEPT.
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The mollusca of Georgian

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