NEPHROPS. 
ASTACUS. Pennant . 
NEPHROPS. Leach. 
CANCER. LinnL 
Antennce in eadem linea horizontali inserts : 
Interiores setis duabus ; superiore crassiore compressa ; inferior c setacea, tereti. 
Exteriores pedunculo art.ir.nlo primo squama ultra pedunculi apicem prodeunte. 
Palpi pediformes articulis quinque exsertis ; articulo primo latere interiore supra denlato, infra 
subserrulato. 
Oculi maximi, reniformes, pedunculo abrupte et multo crassiores. 
Pedes decern ; par anticum majus, intequale, didactylum ; manu filiformi : paria 2 et 3 didac- 
tyla, filiformia; paria 4 et 5 filiformia, ungue terminata ; ungues acuminati, 
Abdomen sex-articulatum ; segmentis lateribus acutis. 
Cauda pentaphylla ; processu exteriore bipartito, articulato. 
Femina coxis tertiisj Mas coxis quintis perforatis. 
Antennae inserted in the same horizontal line : interior ones with two setae ; the upper seta 
compressed; the under seta setaceous, rounded : exterior antennae with a scale on the first joint 
of their peduncle, extending beyond the apex of the peduncle. Pedipalpes with five exserted 
joints; the first joint with the interior side dentated above, subserrulated beneath. Eyes very 
large, kidney-shaped, much and abruptly thicker than their peduncle. Legs ten; anterior pair 
largest, unequal, didactyle ; second and third pairs filiform, didactyle ; fourth and fifth pairs 
filiform, terminated by acuminate claws. Abdomen six-jointed ; the sides of the segments 
acute. Tail with five plates ; the exterior scale articulated. 
The form of the eyes, and the sexual perforations, distinguish this genus from Astacus. 
