348 
GAMMARIDiE. 
A MPHIP OB A . QA MM A RIDES. 
NATATORIA. 
Genus — MCE II A. 
Mcera. Leach, Edin. Encyc. vii. p. 403. Linn. Trans, xi, 
p. 359. Samouelle, Ent. Comp. p. 103. Desha- 
rest, Consid. sur Crust, p. 246. Spence Bate, Cat. 
Amph. Brit. Mus. p. 187 (not Dana). 
Leptothoe. Stimpson, Mar. Invert, of Grand Manan, p. 46. 
Gammarus (pars). Midne Edwards, Hist. Crust, iii. p. 49. 
Generic character. Animal long and slender. Superior 
antennse much longer than the inferior, having a secondary 
appendage. Coxae not so deep as their respective segments. 
Second pair of gnathopoda larger than the first. Pereiopoda 
subequal. Posterior pair of pleopoda biramous. Rami equal. 
Telson double. 
The species forming this genus are long, and not 
very robust. The eyes are normal ; and the antennae are 
long; those of the superior pair have the peduncle con- 
siderably longer than the flagellum, while the inferior 
pair of antennae seldom exceed the length of the 
peduncle of the superior. The oral appendages some- 
what recede from the facial line ; and the mandibles are 
furnished with a tri-articulate appendage. All the legs 
have the coxae less deep than the segments to which they 
respectively belong. The hands of the first two pairs of 
legs are subchelate ; those of the first pair being small, 
while those of the second are large. The thighs of the 
last three pairs are not much dilated. The last pair of 
caudal appendages are biramous, and the branches are 
of equal length. The terminal tail-piece is double. 
