18 
The Little Round Clam, Cytherea conyexa Say, is much 
like the Venus ; but it is more rounded, instead of triangular- 
oval; very convex. Inside it is pure white. It is not a com- 
mon shell, 
The shell here pictured is a most familiar object on the 
| sands. It isthe Petricola 
pholadiformis Lam. 
“ False Pholas” would be 
a good common name, if 
it needs one, for it is very 
much like a Pholas in 
form and ornamentation 
of the surface. Not content with aping the Pholas’ person, 
this Petricola goes so far as to copy their manner of living too. 
It bores into hard mud, or sometimes into wood softened by 
lying in sea water. 
Now comes one of the smallest and prettiest of the common 
clams, Donax fossor Say. When you find Donax at all, you 
are likely to find about a million of them. The shell is trian- 
gular-oblong, smooth except for faint radiating riblets, and of 
a pure white or yellowish color, generally 
having a faint purplish streak from the 
beaks downward. The inside is white, 
tinted with faint orange, or is of a royal 
purple color. The edge of the valve is 
Fig. 14. Donax fossor. finely crenulated. When you find living 
Donax take a few home in a bottle of sea water. They will 
soon reach out the long slender siphons, one for drawing the 
water in, the other conducting it out, after the food particles 
> 
Fig. 13. Petricola pholadiformis. 
* 
<< 
