THE CANCROID CRABS OF AMERICA 



163 



Diagnosis. — Carapace distinctly longer than broad. Chelipeds 

 very unequal. No segments of male abdomen fused. A spine on 

 eye stalk. 



Description. — Carapace elongate-oval, covered with numerous 

 well-separated, small, white, beadlike tubercles which posteriorly 

 become subacute or spiniform. Surface between tubercles covered 

 with very short, light-colored setae. Lateral teeth three besides the 

 orbital tooth; two are antero-lateral, one postero-lateral. Lower sur- 

 face of carapace spinulous. Median tooth of front oblong, twice as 



Figure 25.— Peltasion dextr'jm, m.vle, holotype, dorsal view, X 'He 



long as lateral, which are divergent, each tooth tipped with a sharp 

 spine and having two or more spinules near the tip. Cornea imper- 

 fectly developed, light brown; a small spine on anterior or inner sur- 

 face of eye stalk about one-third the distance from tip. Basal article 

 of antenna attaining end of suborbital tooth, next two articles succes- 

 sively much slenderer. Ischium of outer maxilliped wider distally 

 than the merus, its antero-internal angle produced; inner angle of 

 merus spinulous. Chelipeds very unequal, the right the larger 

 (in the single specimen); surface finely granulate. Merus very thick, 

 trigonal, spinulous on upper and outer margins and toward distal 



