NIPHARGUS. 
311 
A MPHIP 0 DA . GA M MA RIDES. 
NATATORIA. 
Genus— NIPHARGUS. 
Niphargus. Schiodte, Act. Soc. Reg. Dan. 1851, p. 26. Trans. Ent. 
Soc. Lond. 2 ser. v. i. p. 149. Nat. Hist. Review, i. 
p. 43. White, Hist. Brit. Crust, p. 186. Spence 
Bate, Cat. Amph. Brit. Mus. p. 174. 
Gammarus part. Koch, Crust. Myr. u. Arach. Deutschl. h. 5 and 36. 
Costa, Mem. d. reale Accad. d. Sci. Napoli. 1. 
Generic character. Animal slender. Eyes obsolete or rudi- 
mentary. Superior antennae having a secondary appendage. 
Inferior antennae shorter than the superior. Gnathopoda 
uniform, chelate or subchelate. Posterior pair of pleopoda 
biramous; one ramus rudimentary, the other very long and 
double-jointed. Telson single, deeply cleft. 
The animals of this genus are much compressed, 
slender in form, and colourless creatures. The eyes 
are wanting or rudimentary. # The superior antennae 
are very slender, longer than the inferior, and carry a 
very small secondary appendage. The mandibles are 
furnished with a tri-articulate appendage ; and the foot- 
jaws have the squamiform plates but slightly developed. f 
* Caspary (Verhandl. d. Naturf. Vereins fur Rheinland, Jahrg. 6.) and 
Hosius (who kept specimens of N. puteanus alive for many weeks) were 
unable to detect any traces of eyes ; but Gervais (Ann. Sci. Nat. 2 ser. iv. 
p. 128) considered that the species possessed eyes although destitute of 
coloured pigment. In all that we have kept alive, some for several weeks, as 
in N. fontanus, they are imperfectly formed and of a lemon colour. 
4* The first and second maxillse and the foot-jaws do not materially differ 
from those of Gammarus pulex. Hosius indeed figures the first maxilla in 
N. puteanus as having a very slender ex-articulate palpus, but our dissections 
agree with those of Schiodte, showing the palpus to be broad and two-jointed. 
It is probable that the specimen of N. puteanus dissected by Hosius was im- 
mature, as the palpus in very young specimens of G. Jluviatilis, as also figured 
by Hosius, is also slender, and with the joints only indistinctly exhibited. 
