TIUDENS. 



281 



1SOPODA. 



NORM ALIA. 



TRIDENS. 



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

 ment of the tail furnished with three carinae, 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 inch and a half. 



tridens. LEACH, Trans. Linn. Soc. xi. p. 370. Die. Sc. Nat. xii. 

 p. 349. DESMAREST, 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. JEya monophthalma var. minor. 

 JOHNSTON, in London's Mag. Nat. Hist. vii. p. 233, 

 fig. C. (?) 



THIS species is closely allied to &ga bicarinata, but is 

 distinguished by the three carinse 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 



