208 AMPIIIPODA NORMALIA. 



antennoD having the second joint of the peduncle shorter than the 

 firat, third shorter tlian the second ; flagellum twice as long as the 

 peduncle, ha^•ing about twenty-four articuli, broader than long ; 

 secondaiy appendage having about six articuli. Inferior antenna? 

 having the olfactoiy organ well developed ; last two joints of the 

 peduuelo subcqual ; llageUum shorter than the peduncle. Gna- 

 thopoda subequal : propodos of the first pair long-ovate, tapering, 

 ha^'ing the palm very oblique ; of the second pair ovate, palra 

 slightly oblique and concave. Penultimate pair of pleopoda as 

 long as the preceding ; posterior pair of pleopoda ha\ing the rami 

 subequal and jilumose. Colour generally of a ycUowish-brown. 

 Length ^ of an inch. 



Hah. In most of the freshwater streams of England, and probably 

 of all Europe. 



6. Gammarus Edwardsii. (Plate XXXYII. tig. 2.) 



Ganmiarus marinus, Edicnrds, Hist, des Crust, iii. p. 46 (not Leach). 

 Wliite, Hist. Brit. Crust, p. 183. 

 Spence Bate, Synopsis, i^-c.. Aim. Nat. Hist. Feb. 1857. 



Very similar in general appearance to G. Locusta, but more robust. 

 Eyes reniform. Superior antennae about one-third the length of the 

 animal ; first joint of the peduncle nearly as thick as long, second 

 a little shorter and narrower, third still more so ; flageUum nearly 

 as long again as the peduncle ; secondaiy appendage three-articu- 

 lated. Inferior antennae having the peduncle a little longer than 

 the peduncle of the superior, fourth and fifth joints subequal ; 

 flagellum scarcely as long as the last two joints of the peduncle. 

 Gnathopoda short: first pair having the propodos broad-ovate, 

 palm oblique, convex, not defined ; second pair having the pro- 

 podos long-ovate, palm straight, defined, inferior angle produced. 

 Posterior pair of pleopoda having the rami not longer than the 

 peduncle. 



Length |- of an inch. 



Hah. Starcross, Devon, in a pool left by the tide, into which fresh 

 water flows (C. S. B.). Coast of France {Milne- Edwards). 



The animal from which I have taken the above characters agrees 

 with MQne-Edwards's description of Gariimarvs marinus, except in 

 the length of the secondaiy appendage of the superior antennae, which 

 he states to be longer than in G. Locusta, whereas in my specimen 

 it is considerably shorter ; but this is a character that varies during 

 the growth of the animal, and is one very liable to be influenced by 

 change of conditions. In fact, this species, as stated by M. -Edwards, 

 is very possibly only a variety of G. Locusta. 



