CRUSTACEA. 
133 
It inhabits the Dolium ringens, the Triton varie- 
gatum, and other large shells. 
Average length of thorax, four to five inches. 
P. deformis? (Edwards.) Mus. Acad. 
A specimen, brought from the Sandwich Islands 
by J. K. Townsend, agrees with the description of 
this species by M. Edwards, excepting that the 
second and third pairs of feet are tuberculous , if this 
should prove to be an invariable character, the pre- 
sent species may be named P . cavinatus. 
Length of thorax in the only specimen procured, 
rather more than H inches. 
P. symmetricus. Mus. Acad. 
Pedibus cylindricis, manibus tuberculosis, sequalibus, vix 
setosis, infra valdb convexis, pedunculis oculorum gracilibus. 
Eyes very small, scarcely one-fifteenth of the 
length of the ocular pedicles, which are somewhat 
three-sided, slender, rather long, being nearly twice 
as long as the basilar appendage of the external 
antennae, though not so long as the anterior margin 
of the carapax, which is provided with a small, 
somewhat rounded rostrum ; anterior feet equal, of 
moderate size, tuberculous above and beneath, but 
less so on their outer surface, hardly hairy, beneath 
very convex and forming, laterally, nearly a straight 
line with the fingers, which, for a considerable dis- 
tance at their extremities, unite by a black margin, 
and, when closed, form a nearly oval body ; second 
and third pairs of feet long, slender, cylindrical, 
