120 
CRUSTACEA. 
side of the arm bordered by still larger teeth ; a 
spine on the inner side of the carpus. 
If the present species should prove distinct from 
the P. dent ala, it may be named P. angustifrons, 
in contradistinction to the following, which we call 
P. latifrons. Mus. Acad. 
Testa depressa, transverse impressa, pone oculos incisa; 
fronte dilatata, margine multidentata. 
Front between seven and eight-twentieths of the 
width of the carapax, truncate, and not divided 
into lobes by a superficial groove, as in the above 
species, its extremity somewhat folded beneath; 
orbits with a profound notch on the outer side; 
transverse impression of the carapax forming a gen- 
tle curve toward the middle instead of a nearly 
straight oblique line; median impressions subtri- 
angular, large and profound ; disk nearly smooth, 
or almost imperceptibly roughened, postero-lateral 
portion distinctly granulated ; antero-lateral teeth 
somewhat unequal, and much larger than in the 
preceding species, those bordering the feet and 
arm nearly as in P. dent at a ; upper side of the arm 
and hand somewhat roughened. 
Length of the only specimen in the collection (a 
female) hardly 1 T 4 „ inches. 
It is supposed to have been brought from Suri- 
nam., or the West Indies. 
