OTHER EIVALVE: MOLLUSKS 101 
and the covering. A large oscicle, or shelly plate, 
covers the hinge internally. This is especially a 
northern species. 
The southern shell, Entodesma inflata, Conr., the 
Puffed Entodesma, resembles the last, but is smal- 
ler, thinner, and more irregular, and is composed 
largely of epidermis. It is narrow in front, wider 
and thinner behind. 
Verticordia novemcostata, Ad. & Rve., the Nine- 
ribbed Verticordia, has a minute shell, only 4 or 5 
mm. high. In outline it is nearly square, and from 
the beak near one corner run about nine promi- 
nent ribs. The shell is bright pearly within; 
southern. 
Clidiophora punctata, Cpr., the Dotted Pandora, 
is a rare shell of very unusual shape, somewhat 
oblong and beaked. Instead of being inflated it is 
very flat and compressed. The valves are thin and 
silvery, while within they are marked with many 
little pits or dots. It is somewhat over an inch in 
length. From Victoria to San Diego. 
The last family of the Pelycepods is that of the 
Boring-shells, of which there are two divisions. 
The first of these includes the Piddocks, which bore 
their way into clay, shell, or rock; while the 
second division, the Teredos, work chiefly in wood. 
Pholas pacifica, Stearns, the Western Piddock, 
is the first species to be mentioned. The shell is 
thin and delicate, long and cylindrical, marked 
with wavy, concentric ridges and faint radiating 
lines. The sculpturing is not sharply divided into 
two sections, as it is in some of the following 
