DEC A POD A . COR YSTID.E. 



RRACHYVRA. 



GENUS ATELECYCLUS. LEACH. 



. CANCER. Herbst. 



CANCER (HIPPA). Montagu. 



ATELECYCLUS. Leach, Edwards. 



Generic Character. External antenna with the basal articu- 

 lation very large, united to the floor of the orbit at the outer side, 

 and to the front above, thus separating the orbit from the anten- 

 nary fossa : the moveable portion inserted beneath the front, be- 

 tween the orbit and the antennary fossa. Internal antenna lying 

 longitudinally in the antennary fossae, which are, as it were, exca- 

 vated in the front. External pedipalps completely closing the 

 buccal opening, and advancing forwards to the base of the ex- 

 ternal antennae ; the third joint much longer than broad, ter- 

 minating in an oblique line, and giving attachment to the terminal 

 portion in a notch near the middle of its internal margin. Cara- 

 pace more or less approaching a circular form, evenly convex ; the 

 latero-anterior and lateral margins numerously toothed ; the front 

 moderately projecting, quinquedentate, the exterior tooth forming 

 the boundary of the orbit ; the hepatic regions small, the bran- 

 chial very large. Orbits, directed forwards, with a single fissure 

 beneath, and two above, which form a distinct tooth towards the 

 outer angle. Anterior legs very large and strong, short, com- 

 pressed, the hand carinated and ciliated above ; the fingers curved ; 

 the remaining pairs of moderate length, compressed., the ter- 

 minal joint long, acute, and nearly straight. Abdomen in the 

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



This genus was established by Leach for a species found 

 by Montagu, and described by him in the eleventh volume 

 of the Linnsean Transactions, under the name of Cancer 



