118 STALK- AND SESSILE-EYED CRUSTACEA 
Sub-Tribe I. GAMMARIDEA. 
Crevettines, M. Edw. Hist. Nat. Crust. iti, p. 8, (1840). 
Gammaridea, Dana, U.S. Explor. Exped. xiv, Crust. part il, p. 806, 
(1853). 
Gammarina, Spence Bate, Cat. Amphip. Crust. Brit. Mus. p. 4, 
(1862). 
Body of normal shape ; head moderate. Eyes small, rounded. Abdo- 
men narrow, of normal shape. Antenne normally developed, with a 
peduncle and multi-articulate flagellum, Coxe, (or epimere), 
squamiform, and usually large enough to protect the branchial sacs. 
First three pairs of swimming legs consisting of ciliated double 
branched flexible appendages, three last pairs of stiff normally double 
branched stylets. Maxillipeds elongated, and covering the preceding 
appendages of the mouth, one or both of the first two pairs of walking 
legs subchelate. 
Family I. ORCHESTID 2. 
Orchestide, Dana, U.S. Explor. Exped. xiv, Crust. part ii, p. 827, 
(1853); Spence Bate, Cat. Amphip. Crust. Brit. Mus. p. 4, (1862). 
Antenne similar, the upper much shorter than the lower, and with- 
out a secondary appendage. Coxe largely developed. Last pair of 
caudal appendages never longer than the preceding, unibranched, and . 
with the spines never developed into hooks. Hairs on the entire 
animal short and stiff. Mandibles without an appendage. 
The habits of the animals are terrestrial or subaquatic. They con- 
struct no home to rest in, and their mode of progression when out of 
the water is by leaps. 
TALITRUS. 
Talitrus, Latr. Hist. Crust. vi, p. 294, (1803); Spence Bate, Cat. 
Amphip. Crust. Brit. Mus. p. 5, (1862). 
Superior antenne short and rudimentary. Inferior antenne with 
the two basal jomts absorbed into the frontal wall of the head. 
Mawxillipeds not unguiculate. First pair of legs not having a subchelate 
hand in either sex, second pair of legs often smaller than the first pair, 
imperfectly subchelate in both sexes. Coxe of the fifth pair of legs 
subequally bilobed, and nearly as deep as the coxe of the preceding 
pair. Posterior pair of caudal appendages unibranched, 
