44 
are very scarce. Pelecypods are numerous locally where bottom conditions 
afford them congenial footing. Sand beaches and the muck of the small 
lakes afforded excellent collecting grounds for Pisidium, Musculium, and 
Sphaerium, but the Unios were few and far between. There are many 
muskrats (Ondatra zibethica) in the region, and it was found that they were 
feeding to a large extent upon Unios; hence the collectors profited by pick- 
ing over the numerous shell piles which these accommodating animals left 
on the shore for them. Each collection was kept separately, and an effort 
was made to bring in a representative collection from the lakes and rivers 
traversed. 
Family, Unionidae 
Anodonta grand is footiana Lea 
Lakes Fitehie, Bamaji, Stranger, Kimmewin, Botsford, Cat, St. 
Joseph, Hill; Marchington and Pashkokogan rivers. Abundant only at 
the first three localities. This common and widely distributed variety of 
Anodonta grandis is undoubtedly a northern form in distribution as sug- 
gested by Ortmann. It is common in Michigan, Minnesota, Wisconsin, 
and northern New York in the United States, and has been seen from 
Georgian bay, and the northern part of Ontario in Canada. How much 
farther north it may extend is not known. The specimens collected by 
Dr. Cahn are like those from Winnebago lake, the type locality (See Baker, 
1928, I, 157). Not recorded by Whiteaves (1905) from Keewatin. 
Anodonta kennicottii Lea 
Pashkokogan lake and river. Only three specimens of this character- 
istically northern Anodonta were found by the Cahn party. These are like 
those from Wisconsin. Kennicottii is known as far north as Great Slave 
lake. Recorded by Whiteaves (1905). 
Anodonta marginata Say 
Schist lake, one specimen. Typical in form and colouring. This 
species inhabits the Mississippi, St. Lawrence, and Hudson Bay drainages. 
Recorded by Whiteaves (1905). 
Lampsilis superiorensis (Marsh) 
Unio superiorensis Marsh, Nautilus, X, p. 103, PI. 1, figs. 1, 2, 5, 1897. 
This species appears to be the common Lampsilis of the north. The 
shell is much thinner than siliquoidea } the hinge much slighter, the cardinal 
teeth less developed, and the colour more yellowish with fainter rays. The 
hinge is more like that of radiata. The rays are more usually interrupted 
by the lines of growth than in the related species. The rest periods are 
strongly accentuated. In form the shell is always much higher behind the 
umbones than in front of these, a feature well shown in Marsh’s figure. 
The Cahn specimens are much eroded about the umbones and the interior 
of the valves is in many cases discoloured with coppery stains, due to 
distomid parasitism. 
