= 
EGA TRIDENS. 281 
ISOPODA., GID. 
NORMALIA, 

AGA TRIDENS. 
Specific character. Differs from ga bicarinata in having the last seg- 
ment of the tail furnished with three carine, 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. 
ga tridens. LEacu, Trans. Linn. Soc. xi. p. 370. Dic. Se. Nat. xii. 
p. 349. Desmarest, Crust. p. 305. Mitne Epwarps, 
Crust. iii. p, 242. Wurtz, B. M. Cat. Brit. Crust. 
p. 80. Pop. Hist. Brit. Crust. p. 251. 
Var. ? with central spine of tail obsolete. ga monophthalma var. minor. 
Jounston, in Loudon’s Mag. Nat. Hist. vii. p. 233, 
fig. C. (2) 
Tus species is closely allied to Aga bicarinata, but is 
distinguished by the three carinz 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 
