iEGA TKIDENS. 



ISOPODA. 



liORMALIA. 



281 



MGk TRIDENS. 



Specific character. Differs from ^ga bicarinata in having the last seg- 

 ment of the tail furnished with three carinie, each of which is produced into 

 a small point beyond the posterior margin of the segment, the space between 

 the two lateral teeth being emarginate ; eyes large, having only a small space 

 between them in the centre of the anterior margin ; inner plate of the caudal 

 appendages larger than the outer and truncated at its extremity. 



Length, an incli and a haK. 



uEr/a tridens. Leach, Trans. Linn. Soc. xi. p. 370. Die. Sc. Nat. xii. 



p. 349. Desmakest, Crust, p. 305. Milne Edwards, 



Crust, iii. p. 242. White, B. M. Cat. Brit. Crust. 



p. 80. Pop. Hist. Brit. Crust, p. 251. 

 Var. ? with central spine of tail obsolete. Jlya monoiMialnia var. minor. 



Johnston, in Loudon's Mag. Nat. Hist. vii. p. 233, 



fig. c. (0 



This species is closely allied to JEga bicarinata, but is 



distinguished by the three carinae on the terminal segment 



of the tail, the two lateral ones being the strongest, and 



each terminating in a small tooth on the posterior edge of 



