252 
GAMMARTDiE. 
AMPHIPODA. GAM MART DBS. 
NATATORIA . 
Genus— PHERUSA. 
Pherusa. Leach, Edin. Encyc. vii. p. 432. Trans. Linn. Soc. xi. p. 360. 
Enc. Brit. Suppl. p. 426. Desmarest, Consid. sur. Crust, 
p. 269, pL xliv. Spence Bate, Cat. Amph. Brit. Mus. 
p. 143. (Not of Koch, Deutschlands Crustaceen, &c. Heft, 
xxix. pi. 24, which is an Isopod.) 
Amphitoe. Milne Edwards, Ann. des Sci. Nat. t. xx. p. 376. Hist, des 
Crust, iii. p. 32. 
Amphithoe . Dana, United States’ Explor. Exped. p. 910 (part). 
Generic character. Like Atylus, but telson not divided. 
Gnathopoda small. 
This genus is very near to Atylus ; in fact, the de- 
marcation through some of the exotic species is so 
feeble, that some carcinologists may doubt the pro- 
priety of our separating them. Atylus Huxleyanus , from 
Hermit Island (Antarctic Ocean) indeed might be al- 
lotted to either genus, since the cleft in the terminal 
caudal plate is reduced to a mere indentation of the 
apex. But since, in this and other nearly-allied genera, 
there are many species which can be grouped into sepa- 
rate divisions, we think that it will be found convenient 
to consider them as forming separate genera. 
In addition to the entire central caudal plate, which 
is the chief distinction between this genus and Atylus , 
the difference in the form and size of the gnathopoda 
separates it from Calliope . 
