102 CRUSTACEA. 



In some, where the tail always consists of six segments, the length 

 of the inferior antennae never surpassed the half of that of the body. 



We will begin with those whose mandibles, as usual, are but 

 slightly, or in no degree salient. 



Cymothoa, Fab. 



The antennae nearly equal in length; eyes scarcely apparent; last 

 segment of the tail forming a transverse square; the two pieces ter- 

 minating the lateral fins, linear, equal and styliform(l). 



Icthyophilus, Lat. Nerocila, Livoneca, Leach. 



The antennae, equal in length, and but slightly visible eyes; the 

 last segment of the body almost triangular; the two pieces termi- 

 nating the lateral fins in the form of leaflets or laminae, the exterior 

 of which is largest in the Nerocilae, and of the size of the other in 

 Livoneca(2). 



In the four following subgenera the superior antennas are mani- 

 festly shorter than the inferior. 



In several, as in Cymothoa, all the feet are terminated by a small, 

 stout, and strongly curved nail; the last eight are not spinous; the 

 eyes are always separated and convex. They form three genera in 

 the system of Leach, but may be united in a single subgenus, under 

 the common denomination of one of them, or the 



Canolira, Leach. Anilocra, Olencira, Ejusd. 



The laminae of the fins in the Olencirae(S) are narrow and armed 

 with spines. In the Anilocrae(4) the external leaflet of the same 

 parts is longer than the internal; the reverse is the case with the 

 Canolirae(5). The eyes, besides, are but slightly granulous while in 

 the preceding that disposition is evident. 



In the three following subgenera, the second, third and fourth feet 

 alone are terminated by a strongly curved nail, and the last eight 

 are spinous. The eyes are usually but slightly convex; they are 

 large and converge anteriorly. 



(1) Cymothoa sestrum, Fab.; Desmar., Consid., XLVI, 6, 7; C. imbricata, Fab. 

 For the other species, see Desmar., loc. cit. 



(2) See Desmar., op. cit., p. 307, genera Nerocila and Livoneca, and various spe- 

 cies of Cymothoae of Hisso, p. 310, 311. 



(3) Desmar., Consid., p. 306. 



(4) Desmar., Consid., Anilocre du Cap, XLV1II, 1- 



(5) Desmar., Consid., p. 305. 



