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DESCRIPTION OF SPECIES 
Sphaerium simile Say 
Plate VI, figures la-ld 
Shell large for the genus, transversely oval, umbones 
inflated just in front of middle of shell, making it thus nearly 
equilateral; dorsal margin almost straight; ventral margin 
gently rounded, anterior and posterior margin rounded ; lines of 
growth distinct but not very coarse, with occasional concentric 
ridges. Cardinal teeth small, lateral teeth double in the right 
and single in the left valve. 
*L. 16 H. 11-25 B. 8-25 
Locality. Lot 7, Eastview. 
This bivalve is not common. It is by far the largest of the 
fossil Sphaeriidse and hence is readily recognizable. The nearly 
median position of the beaks is a feature distinguishing this form 
from others likely to be encountered in the Ottawa valley. 
Sphaerium striatinum Lamarck 
Plate VI, figures 2a-2d 
Shell inequilateral, solid; umbones placed anterior to 
centre of shell, smooth or covered by fine lines, dorsal margin 
arched, ventral rounded, posterior margin obtusely angled, 
anterior margin rounded. Lines of growth coarse toward the 
ventral margin of the shell; cardinal teeth small and incon- 
spicuous, lateral teeth more prominent, double in the right, 
Single in the left. 
L. 9-75 H. 8 B. 5-5 
Locality. Lot 7, Eastview. 
From the preceding species 5. striatinum may be disting- 
uished by its more markedly inequilateral shell and smaller size. 
It is fairly common.’ 
1 Abbreviations used throughout report: H. = height in mm.; . B. = 
breadth in mm.; L. = length in mm.; G.D.= greater diameter in mm, 
b.D. ^smaller diameter in mm.; L.D. =lesser diameter in mm.; W. = width 
in mm.; A.H. =aperture height in mm.; A.W. =aperture width in mm. 
19856—5 
