326 GA.MMAR1DJ:. 



AMPHIPODA. GAMMARIDES. 



NATATORl.-l. 



Genus— CRANGONYX. 



Crangonyx, Spence Bate, Proceed. Dubl. Univ. Zool. and Bot. Assoc. 

 1859. Nat. Hist. Rev. vol. vi. p. 165. Cat. Ampli. Crust. 

 Brit. Mus. p. 178. 



Generic character. Superior antennae having a secondary 

 appendage. First pair of gnathopoda rather larger than the 

 second. Posterior pair of pleopoda unibranched, not longer 

 than the preceding pair. Telson single, entire. 



In this genus the eyes are imperfectly developed. 

 The superior antennae are not much longer than the 

 inferior, but rather more robust, and furnished with a 

 secondary appendage. The first two pairs of legs are 

 small, rather unequal in size, and subchelate. The 

 caudal appendages are short, and the last pair terminate 

 in a single bi*anch, not longer than the preceding pairs. 

 The terminal central plate is also single. 



This genus, like the last, belongs to the subterranean 

 Fauna. A single species as yet is all that has been 

 found in England ; but we have little doubt but that 

 Gammarus Ermanni of Milne Edwards, which was found 

 by M. Ermann in the warm springs of Kamschatka, 

 belongs also to this genus. 



It is curious that we should have to record, that while 

 the animals of this genus (as in the preceding) inhabit 

 the deep artificial wells, without being known to exist 

 in our rivers and streams, its nearest allied form is to be 

 found in a marine genus, Gammarella. 



