46 
CALIFORNIA SEA SHELLS. 
venture however to illustrate two species, trust- 
ing that the student will carefully notice the ine- 
quality of the ears of the shell, and especially 
the little notch beneath one ear, through which 
the animal moors itself at times, by a series of 
threads, called byssus, 
Pecten cequisulcatus , Cpr., Fig. 2, PI. XII, is 
an inch or two in diameter, strong, full, brown- 
ish, and marked by about twenty equal ribs. 
Pecten latiauritus , Conr., Fig. 3, PI. XII, is 
very thin and delicate, having about fifteen 
rounded ribs. The ears are broad and unequal, 
the shells but little ar.ched, while the color is 
brown, variously mottled with white like the 
feathers of a hen ; size, from one-half to one inch 
in diameter. These little shells live attached to 
sea- weed ; occasionally a storm tears up the weed 
and washes it ashore, thickly studded with these 
little beauties. 
Pecten hastcttus , Sby., is a much larger and 
stronger shell, elongated, with very unequal ears, 
many line, and a few prominent ribs. Color, 
pinkish. 
We now come to a notable California species, 
j Hinnites giganteus , Gray, Fig. 4, PI. XII, some- 
times called the Rock-oyster. In its early life 
it has a free, symmetrical shell looking like a 
Pecten. It is then distinguished by its very un- 
equal ears, and the twelve prominent, serrate ribs 
on the upper valve. It soon settles down for 
life in some convenient and sheltered spot, such 
as the inside of an old Haliotis shell, fastens its 
lower valve to this support, and yields itself up 
