DEC A POD A . CA NCERIDJE. 



BRACHYURA. 



GENUS CANCER. 



Cancer, Linn. Leach, Bell. 



Platycarcinus, Latr. Edwards. 



Generic Character. — External antenna with the basal joint 

 very long and thick, filling the hiatus between the inner canthus 

 of the orbit and the front, and terminating forwards in a strong, 

 angular, tooth-like projection, directed forwards and slightly in- 

 wards, reaching a little beyond the frontal line ; the terminal por- 

 tion is very short and slender, and arises from the internal part 

 of the basal joint, nearer to the cell of the internal antennae than 

 to the orbit. Internal antenna directed forwards, placed in longi- 

 tudinal cells. External pedipalps with the third joint excavated 

 at the anterior and inner margin. Anterior feet nearly equal, 

 robust ; the others, more or less hairy, but without spines. Cara- 

 pace transversely elliptic, somewhat elevated, with the regions 

 obviously marked ; front trifid ; orbits with a strong tooth over 

 the inner canthus ; and with two fissures above, and one be- 

 neath : the latero-anterior margin on each side extends back to 

 the centre of the cardiac region, and passes off into a sinuous, 

 granulated ridge, which rises over the latero-posterior margin ; 

 it is divided into ten lobes, of which the last is very small, and 

 often obsolete. Eyes placed on short peduncles. Abdomen, in 

 the male, five-jointed ; in the female, seven -jointed. 



This genus is readily distinguished from its immediate 

 congeners by the form of the basal portion of the external 

 antennse, by the direction of the internal antennae, and by 

 the form of the latero-anterior margin of the carapace, 

 which is, in this genus, uniformly ten-toothed. There is 



