MICRODEUTOPUS. 287 



A MPH1PODA . GA MM A RIDES. 



NATATORIA. 



Genus MICRODEUTOPUS.* 



Microdeutopus. COSTA, Rend, delle Reale Accad. delle Sci di Napoli, 1853, 



s. 171. 



Microdentopus. 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 ff. LILJEBORG, Ofvers. af Kongl. Vet. Akad. 



Forhandl. 1854, p. 455. 



Generic character. Superior antennae 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. 



