CIJAMA. 
49 
Cpr., probably a variety of this species, is shorter 
and broader, with a glossy epidermis. It may 
be found near the entrance to the Golden Gate. 
Another mussel-like shell, shown in Fig. 2, PI. 
XIII, is Septifer bifurcatus , Eve, Its generic 
name, “ partition bearer,” was given from the 
fact that a little, internal, shelly partition 
stretches across each valve at the apex ; while 
the specific name, “ two-forked,” refers to the ex- 
ternal ribs by which the shell is marked, which 
often divide into two. It is strong, white and 
nacreous within, and covered with a dark epi- 
dermis without ; the average length is one inch. 
It may be found, at low tide, attached to the 
rocks by a byssus. 
The next species, Chama pellucida , Sby., an 
internal view of which is shown in Fig. 3, PL 
XIII, might easily be overlooked when it is tirm- 
ly fastened to a rock. The outer surface is gray 
or greenish, sometimes dashed with rosy red, 
very rough, and marked by many (dose frills, 
which are translucent, like chalcedony. The 
hinge tooth is very strong, and the inside is lined 
with a white, opaque layer, beautifully crenulated 
at the edge. It grows from one to two inches in 
diameter, and may be found at low tide, firmly 
grown to the rocks, which must be broken to get 
the entire shell. The name “ Chama,” is very 
old, having been mentioned by Pliny. 
Quite unlike the Ohamas are the Cockles, or 
Heart-shells. Beautiful in outline, regular in 
growth, and free to move, they but little resem- 
ble their irregular, hap-hazard, stationary neigh- 
bors. The animal has a remarkably long foot, 
