256 WEST AMERICAN SHELEES 
but the shell is nearly cireular, thick, high arched, 
and externally corrugated. It has only two or 
three open holes, but these are quite large, and 
the central muscle impression is wide and very 
brilliant. It is a southern species, and is usually 
found below low water mark. 
Halictis assimilis, Dall, the Threaded Abalone, 
is now considered to be a distinct species. It lives 
in deep water, from Monterey to San Diego. A 
specimen from the latter city measures four inches 
in length and three and a quarter in breadth. It 
has seven open holes, and the exterior of the shell 
is marked with many threads, like tapestry car- 
peting. There is a moderate furrow below the line 
of holes. The spire is short but quite distinct, 
the body of the shell high arched. Externally the 
shell is reddish, while the inside is smooth and 
silvery, without visible muscle-sear. The shell is 
tolerably thick, and appears very compact and 
solid. 
Quite in contrast with this species is the next, 
*Haliotis gigantea, Chem., the Japanese Abalone, 
which seems to have followed the warm ocean cur- 
rent past the Aleutian Islands, and to have reached 
the central part of the California coast, becoming 
smaller as it progressed, so that here it does not 
deserve its original name, though there seems to 
be no sufficient reason for separating it even as a 
variety. My best specimens came from the west 
coast of Vancouver Island, the largest measuring 
5 inches in length. In shape it appears long and 
narrow, when compared with other species. The 
