108 
CRUSTACEA. 
One specimen, brought by Mr. Nuttall from 
western America. 
Length, of carapax, scarcely one inch. 
Genus Chorinus, (Leach.) 
The following species of Chorinus is preserved 
in the Museum of the Academy without any indi- 
cation of its name or locality ; as it disagrees in its 
details with the only four species of the genus 
which I have seen noticed, viz., the C. aries, (Latr.) 
the C. her os, (Herbst.) and the C. aculeata, and C. 
Dumenlii , (Edwards,) I have ventured to describe 
it as new. 
Chorinus armatus. Mus. Acad. 
Pedum pare antico spinoso; manibus tuberculosis; spinis 
frontis divaricantibus, testa lanuginosa, utrinque 4-spinosa, 
postice 2-spinosa. 
Body elongate pyriform ; frontal spines extreme- 
ly long, divergent; supra-orbitar spine very strong ; 
post-orbitar spine dilated at base, and moderately 
produced. Shell depressed in the middle, but an- 
teriorly convex, on each side moderately convex; 
an obtusely rounded elevation behind the middle ; 
apex somewhat produced, crowned with a short 
spine, having another behind it ; sides, each with 
four great spines, exclusive of the post-orbitar one. 
Feet downy; anterior pair about times the 
length of the carapax; arm spinous; hand and 
wrist studded with granules; posterior feet smooth, 
second pair nearly 11 times the length of the third. 
