MICRODEUTOPUS. 
287 
A MP HIP OP A . GA MM A RIDES. 
NAT ATOM A. 
Genus— MICRODEUTOPUS.* 
Microdeutopus. Costa, Rend, delle Reale Accad. delle Sci di Napoli, 1853, 
s. 171. 
Microdeutopus. Spence Bate, Cat. Amph. Brit. Mus. p. 163. 
Lembos. Spence Bate, Rep. Brit. Assoc. 1855. Ann. Nat. Hist. 
2 ser. xix. p. 142. White, Pop. Hist. Brit. Crust, p. 180. 
Gammarus. Division . Liljeborg, Ofvers. af Kongl. Yet. Akad. 
Forhandl. 1854, p. 455. 
Generic character. Superior antennse longer than the in- 
ferior, and furnished with a secondary appendage. Inferior 
antennae more robust than the superior. First pair of gnatho- 
poda larger than the second, complexly subchelate. Second 
pair smaller than the first, subchelate. 
In this genus the animals are generally long and 
slender. The eyes are small. The superior antennae 
are longer than the inferior, and not so robust. The 
mandibles are furnished with a three-jointed appendage. 
The arms terminate with subchelate hands, and, as in the 
two preceding genera, are developed contrary to the 
general distinction among Amphipoda, the first being 
larger and more perfect than those of the second pair. 
The last pair of legs are much longer than the others. 
The last pair of caudal appendages are double-branched. 
The terminal tail-piece is conical, tubular, with a double 
apex, which appears to arise out of the largest part. The 
exact form of the caudal tail-piece is peculiar to this 
genus, although it bears a near resemblance to the same 
organ in Aora and Stimpsonia. It appears like a true 
* Signor Costa’s generic name, Microdeutopus, would more properly be 
written Microdeuteropus, it being given to the genus in allusion to the minute 
size of the second pair of legs. 
