CALIFORNIA SEA SHELLS. 
lies A. pelta, with a wider border round the 
margin. This shell seldom grows more than 
an inch in length, and is often smaller. 
Acmcea spectrum , Nutt., Fig. 7, PL X, is a 
small species, frequently found growing on the 
shells of other species. It is flattened, with very 
strong, irregular ribs, which project so as to give 
it a serrate edge. It is of a gray color outside, 
and the inner surface is irregularly marked with 
black and white. 
Loitia gigantea , Gray., Fig. 1, PL IX, is a 
fine species, dirty brown or spotted outside, but 
within it is of a very dark and glossy brown, 
with a distinct, long, horse-shoe shaped muscular 
impression. The shell is long, and flattened, 
with the apex near one end. Length, one to 
three inches. 
The Chitons are very strange animals, some- 
what resembling limpets in shape, and like them 
clinging to the rocks by a broad, flat foot. 
Their shells, however, are not single, but com- 
posed of eight plates, which overlap like the 
scales on a coat of mail. These plates are sur- 
rounded and partly covered by a muscular man- 
tle, which is often fringed and ornamented. In 
their early life the voung chitons have little re- 
semblance to the more adult forms, for then they 
consist of only two parts, head and body. Grad- 
ually the body becomes covered with seven 
plates, and the head takes shape and developes 
the eighth. Chitons are a very inoffensive class 
of animals, and like to live in retired places, 
especially under stones. Our species are quite 
numerous, but we will mention only those which 
