DEC A POD A. 



BRACHYURA. 



GENUS PISA. 



CANCER, Penn. Herbst, Montagu. 



IN.UHUS, Fabr. Risso. 



MAIA, Latr. Bosc. 



I'I.SA, Leach, Desmar, Edwards. 



Generic character. External antenna beset with club-shaped 

 nairs; the basal joint longer than broad, extending beyond the 

 inner canthus of the orbit j but concealed above by the strong spine 

 which proceeds from the upper margin of the orbit : second joint of 

 the antennae rather slender, inserted a little behind and on the 

 outer side of the rostrum. External pedipalps very broad, the 

 second joint produced at the inner and anterior angle ; the third 

 triangular, very broad at the outer margin ; the anterior and inner 

 angle truncate or emarginate. First pair of feet in the adult male 

 very large, longer than the second pair ; the hand thick and the 

 fingers meeting only at the outer margin of the points which are 

 toothed ; those of the female much smaller, the fingers meeting 

 throughout nearly their whole length ; shorter than the second pair. 

 The remaining feet moderately long, diminishing regularly from 

 the second to the fifth, cylindrical, the terminal joint curved, 

 pectinato-denticulated beneath, naked at the extremity. Eyes 

 scarcely thicker than their peduncles, capable of being reflected in 

 the orbits. The orbits oval, directed outwards and downwards ; 

 their upper margin with a strong triangular spine directed forwards. 

 Carapace triangular, terminating in a strong bifid rostrum, divari- 

 cating at the extremity. Abdomen seven-jointed in both sexes. 



