2U 
GAMMARIDiE. 
A MPHIP OB A . PH OXIDES. 
NATATOUTA. 
Genus — ISiEA. 
Iscea. Milne -Edwards, Ann. Sci. Nat. t. xx. p. 380. Hist, des Crust. 
t. iii. p. 26. Spence Bate, Ann. Nat. Hist. 2 ser. xix. p. 142, 
1857. Cat, Ampin Crust. Brit. Mus. p. 122. White, Pop. Hist. 
Brit. Crust, p. 179. 
Generic character. Superior antennae having a secondary 
appendage. Gnathopoda subchelate; second pair the larger. 
Pereiopoda subchelate. Posterior pair of pleopoda biramous. 
Telson cylindrical, single. 
In this genus the cephalon is not much produced 
anteriorly. The eyes are two. The superior antennae 
are longer than the inferior, and furnished with a se- 
condary appendage. The arms are subchelate ; the 
hand of the second pair is larger than that of the first ; 
all the legs are likewise subchelate, the distal extremity 
of the hands being broadly dilated on the side towards 
which the joints bend. The coxae of the four or five 
anterior pairs of legs are deep. The last pair of caudal 
appendages are double-branched, and the central tail- 
piece is round and solid, the alimentary canal probably 
opening at its posterior extremity. 
Dana has established a subfamily to receive this genus, 
together with Anisopus of Templeton, under the name of 
Isceance , based upon the subchelate condition of the walk- 
ing legs. We do not perceive any advantage to be de- 
rived from this arrangement, since Iscea and Anisopus 
(which latter we consider to belong either to the genus 
Amphithoe or Sunamphithoe) cannot be embraced in the 
same subfamily; and it will be found that there are other 
species possessing a more or less perfectly marked sub- 
chelate condition of the walking legs, which cannot be 
associated with Iscea. 
