ISOPODA. 



NORM A LI A. 



NJISA BIDENTATA. 431 



SPH^ROMIDJE. 



NyESA BIDENTATA. 



Specific cJmracter. Colour ashy, varied with reddish or bluish streaks ; 

 sixth segment of the pereion large, overhanging the base of the pleon, which 

 has two oval rugose tubercles in the middle. 



Length, about one-third of an inch. " Six lines" — Leach. 



Oniscus hidenfatua. Adams, Trans. Linn. Soc. vol. v. p. 8, t. 2, f. 3, 4. 



Nresd hidenfata. Leach, Diet. Rci. Nat. xii. p. 341. Edinb. Enc. vii. 



p. 405. Trans. Linn. Soc. xi. p. 367. Suppl. Enc. 

 Brit. i. p. 427. Samouelle, Ent. Compend. p. 108. 

 Milne Edwards, Crust, iii. p. 217. Desmarest, 

 Cons. Crust, p. 295, t. 47, f. 2. White, B. M. Cat. 

 Brit. Crust, p. 78. Pop. Hist. Brit. Crust, p. 247, 

 pi. xiv. f. 1. GossE, Man. Mar. Zool. 1, 135, fig. 237. 



This species is at once distinguished from all the other 

 British species of the family by the structure of the 

 hirge sixth segment of the body, armed on its hind 

 margin in the middle with two long divergent, slightly 

 incurved rugose teeth, which completely conceal the 



