OYSTERS AND SMALL CLAMS 5 
or 
Aximopsis viridis, Dall, the 
Green Axinopsis, is shown in Fig- 
ure 59. The polished, pale-green 
periostracum gives the shell its 
specific name. It is only a quar- 
ter of an inch across. Dredged 
from muddy or sandy bottom. 
This little mollusk lives along the 
eoasts, from Japan and Bering Strait down to 
Catalina Island. How full of life are the waters 
of the ocean! 
Axinopsis sericatus, Cpr., the Silky Axinopsis, 
is very similar, but the outline is less cireular. 
From Puget Sound, also Alaska and California. 
The silky epidermis suggested its name. 
Diplodonta aleutica, Dall, the 
Arctic Diplodonta, ranges from 
the Pribilof Islands to the Aleu- 
tian chain, and eastward to the 
Shumagin Islands. The picture 
represents a young specimen, 
having a silky, olivaceus epider- 
mis. Other species grow to the length of an inch 
or more, and are coarse and chalky. 
Diplodonta orbélla, Gld., the Round Diplodonta, 
is a not uncommon California shell. It is a pretty 
species, smooth and white, and the valves are so 
much inflated that small specimens resemble white 
marbles. It is said that the animal has a habit of 
forming a protecting nest of sand, cemented by 
mucous. This nest has long, tubular openings for 
the siphons, so that the inmate is wholly concealed. 
Fig. 39, x + (*) 
Fig. 40, x 7 (*) 
