NCENIA. 471 



AMPIIIPODA. PODOCERIDES. 



NATATORIA. 



Genus— NCENIA. 



Ncenia. Spence Bate, Cat. Amph. p. 271. 



Generic cliaracter. Antennas subequal ; superior pair with- 

 out a secondary appendage; inferior having the flagellum 

 multi-articulate. Guathopoda subchelate. Posterior pair of 

 pleopoda biramous. Telson cylindrical. 



The animals of this genus are somewhat compressed. 

 The eyes are round. The superior antennas are about 

 the same length as the inferior ; the latter originate 

 posteriorly to the superior, and terminate in a multi- 

 articulate flagellum. The first two pairs of legs have 

 subchelate hands, the second pair being much larger 

 than the first. The walking legs are tolerably robust, 

 and not very long. The posterior pair of caudal ap- 

 pendages terminate in a pair of styliform branches. The 

 middle tail-piece is tubular, and tipped with one or two 

 rudimentary denticles. 



This genus bears considerable resemblance to Eurys- 

 tlieus, and it is with much hesitation that we have 

 placed them in different families.* The species are rare, 

 and it is not improbable, when more individuals are 

 obtained, that some of the supposed species here de- 

 scribed, chiefly founded on the structure of the hands, 

 may prove only varieties of other species. 



* We have not been able to identify tlie Gammarus spinipes of Dr. 

 Johnson (Zool. Journ. iy. p. 417), taken among Sertularia, from deep water 

 on the Berwicksliire coast, but are inclined to refer it either to the jiresent 

 genus or to Eurf/sihcus, the character given of the first two pairs of legs 

 agreeing tolerably well with those of Eui-j/slhetis binpinimanus (ante, p. 357). 



