52 
GAMMARIDiE. 
structure, the head, much of the posterior part of the 
body, and all the legs and other appendages. 
In the absence of an articulated appendage to the 
mandibles, and the unibranched termination of the 
posterior pair of caudal appendages, some of the genera 
approximate to the Orchestiim:, whereas others gradu- 
ally approach the forms of the next sub -family of the 
Gammarim;. 
There are but two genera which represent this sub- 
family upon the British coasts, all the rest being exotic. 
Some species of Stenothde, a genus that differs from 
Montagua in no very marked degree, found upon the 
coast of the United States, bear a representative rela- 
tion to the British forms. 
