A ORA. 
279 
AMPHIPODA. GAMMA RIDES. 
NAT ATOM A. 
Genus — AORA. 
Aora. Kroyer, Tidsk. ser. 2, i. p. 335, 1845. Spence Bate, Cat. 
Amph. Brit. Mus. p. 160. 
Lalaria. Nicolet, in Gay’s Historia de Chile, vol. iii. 1849. Spence 
Bate, Ann. Nat. Hist. xx. p. 525, 1858. 
Lonchomerus. Spence Bate, Rep. Brit. Assoc. 1855, p. 58. Ann. Nat. 
Hist. 2 ser. xix. p. 143. White, Hist. Brit. Crust, p. 180. 
Generic character. Superior antennae longer than the in- 
ferior; furnished with a secondary appendage. First pair of 
gnatliopoda larger than the second, having the meros infero- 
distally produced as far as the extremity of the carpus. Seventh 
pair of legs longest. 
In this genus the animal is long and slender. The 
superior antennae are very long and are furnished with a 
slender secondary appendage. The inferior antennae are 
about half the length of the superior and furnished with 
a very short flagellum. The first pair of legs are very 
long, complexly* chelate, having the metacarpal joint 
infero-dis tally produced so as to meet the apex of the 
finger when closed. The second pair of legs are sub- 
chelate and much smaller and shorter than the first. 
The last pair of walking legs are much longer than the 
others. The caudal appendages are double-branched, 
and the terminal caudal plate is tubular. 
The modifications of form, and consequently of func- 
tion, which the two first pairs of legs undergo in different 
groups of Amphipoda are nowhere more interestingly 
* We use the term “complexly chelate” where the prehensile organ is 
formed by more joints than the propodos and dactylos. 
