IONE THORACICA, 255 
ISOPODA, BOPYRIDZ. 
NORMALIA. 


IONE THORACICA. 
Male.—Narrow, subparallel, first segment of the body shorter than the 
following, the remainder with the sides subangulated. 
Female.—Pyriform, flattened, basal appendages of the tail multi-ramose. 
Length of female, about one-quarter of an inch. 
Oniscus thoracicus. Monract, Trans. Linn. Soe. ix. p. 108, pl. 5, f. 3. 
Oniscus (Ione) thoracicus. LatTREILLE, Enc. Méth. pl. 336, fig. 46. 
Tone thoracicus. LatREILLE,in Régne An. Ed. i. iii. p. 54. LAMARcK, 
Hist, Anim. sans Vertébres, v. p. 170. Drsma- 
REST, Cons. Crust. p. 286, t. 46, f. 10. Guiirin 
MénévittE, Icon. R. Anim. Crust. t. 62, 
f. 1,2. Miunz Epwarps, Crust. iii. p. 280, 
t. 33, f. 14, 15. Cuvimr, Régne Anim. (Edit. 
Crochard) Crust. t. 59, f. 1. Wuirr, B. M. 
Cat. Brit. Crust. p. 81. Pop. Hist. Brit. 
Crust. p. 254, pl. xiv. f. 8a (male), b (female). 
Ir is to Colonel Montagu that we are indebted for the 
first knowledge of this interesting parasite, which inhabits 
the branchial cavity of Callianassa subterranea, concealing 
