138 
CRUSTACEA, 
thalmic ring armed above with four spines, placed 
two and two, the anterior pair being larger than 
the others; abdomen with obsolete, minute spots, 
and scattered punctures ; segments each with a pro- 
found, hairy, transverse sulcus, not reaching the 
middle, excepting on the last segment, where it is 
scarcely interrupted ; feet vittate alternately with 
red and olivaceous. 
Length from five to nine inches, as measured in 
two specimens, brought by Messrs. Nuttall and 
Townsend from Upper California, where it is used 
as food by the natives.* 
It is probably allied to the P. Argus , (Latr.,) and 
to P. dasypus, (Latr.) 
Fam. Astacidcs. 
Genus Astacus, (Fabr.) 
A. oreganus. Mus. Acad. PI. VII. 
Testa granulata, bimaculata, fronte valde products. 
Body fuscous, granulated, carpus with a sharp 
spine at the interior inner angle; arm produced 
into a spine on each side anteriorly ; thorax behind 
the front with five spines, placed three before, and 
one on each side behind the lateral ones ; a large 
reddish spot on each side posteriorly ; front little re- 
flexed on the sides, terminating in a very long, 
slender spine, and having a short, marginal spine 
on each side. 
Length about four inches. 
* Since the above description was written, Mr. Nuttall informs me 
that he has found specimens of this species two feet in length. 
