204 CRUSTACEA. 



Penceus monodon, Fab. ; Squilla indica,Bont., Hist. Nat., p. 

 81, which inhabits the Indian Ocean. 



P. antennatus, Risso, Crust., II, 6, and P. mars. Id., II, 5, 

 also appear to belong to it. 



Stenopus, Lat. 



Distinguished from the Peneei by the transverse and annular 

 divisions of the two penultimate joints of the four posterior feet. 



The entire body is soft ; the antennpe and feet are long and slender, 

 those of the third pair widest. 



But a single species is known. It was bro\ight from tlie seas 

 of New Holland by M. Peron and Lesueur. Olivier retains it 

 in the genus Palsemon — Cancer setiferm, L.; P .hispidus, Oliv., 

 Encyclop. and Atl. d'Hist. Nat., CCCXIX, 2; Seba, Mus., Ill, 

 XXI, 6, 7 ; Herbst., XXXI, 3, where I first placed it. 



The remaining Carides, the intermediate antennae of many of 

 which are terminated by three threads, liavo at most but two pairs 

 of didactyle claws formed by the four anterior feet. 



A subgenus founded on a single species peculiar to North America, 

 that of 



Atya, Leach, 



Is removed from all analogous Crustacea by an anomalous charac- 

 ter. The forceps terminating the four claAVs is cleft down to its 

 base, or seems to be composed of two fingers in the form of thongs 

 united at their origin ; the preceding joint is crescent-shaped. The 

 second pair is tlie largest. The intermediate antennse have but two 

 threads. 



In all the following subgenera, the blades of the forceps originate 

 at a certain distance from the base of the penultimate article, or of 

 that which has the form of a hand ; the body or the part that i)re- 

 cedes it is not lunulated. 



We now have in the first instance those Carides whose feet are 

 genirally robust and not filiform, and which have no appendage to 

 their external base. Their body is neither very soft nor greatly 

 elongated. 



Among these subgenera, whcs" feet are dejjrived of this a})pen- 

 dage, the three following present an insulated form with respect to 

 their claws. 



Crangon, Fab. 



The two anterior claws, which are larger than the subsequent feet, 

 have but a single tooth in i)lace of the index or immoveable finger, 

 and that which is moveable is bent and hooked. 



The superior or intermediate antennre have but two threads. Tlie 

 second feet are folded up,, and are more or less distinctly bifid or 

 didactyle at their extremity ; neither of the joints is annidated. The 

 rostrum is very short. 



We do not separate the Egeon, Risso, or the Pontophilus, Leach, 

 from Crangon. In the former, the last joint of the external foot- 

 jaws is twice the length of the preceding one, while in the latter 



