254 
CYCLAD^. 
116 . 3. Cyclas pallida, — Shell oblong, pale whitish 
Fig. 61 . yellow on the circumference^ 
slightly concentrically striated, 
rounded before, rounded and ra- 
ther truncated behind ; sides 
C. pallida. rather swollen, evenly convex; 
the cardinal edge rather produced, nearly 
straight, and slightly compressed on each side 
the umbo ; the umbo regularly convex, rather 
in front of the middle of the shell, sometimes 
slightly crumpled. The foot very large ; the 
siphons elongate, united nearly to the tip ; the 
apices conical, the upper the smallest. The 
young are compressed, rather rounded, gra- 
dually becoming more gibbous and elongated as 
they increase in size. 
Sphserlum pallidum. Gray.^ Ann. and Mag. N. H. vii. 465. 
1856. 
Inhab. Grand Junction Canal near Kensal Green. 
The largest specimens are of an inch long, 
W high, and thick. The average-sized specimens 
are \ inch long, \ thick, and high. 
The living specimens emitted, when in confinement, 
several young shells about 1 line long. 
They are decidedly distinct from any of our British 
specimens, but bear a very great resemblance to 
Cyclas rhomboidea of Say, found in the rivers of 
North America. We have unfortunately only a 
single specimen of this species in the British Museum, 
which was sent from the Ohio by Mr. Anthony. 
This example only differs from the specimens found 
by Mr. Bowse in the front side being rather at- 
