108 A HEVISION OF THE BKITISH SPECIES OP 



Posterior margin of the last thoracic segment produced back- 

 wards, and forming two large acutely angulated cusps. Caudal 

 rami and last abdominal segment densely hispid; rami about 

 seven times as long as broad ; principal caudal setae more than 

 half as long as the abdomen, very flaccid and finely plumose ; 

 attachment of the lateral setae distant from the apex about one 

 third the length of the ramus ; anterior antennae reaching to 

 the penultimate thoracic segment. Penultimate joiat of the 

 fifth pair of feet in the female scarcely longer than the preceding 

 joint, produced inwardly and forming a large dagger-like spine 

 which occupies the whole internal margin of the joint ; external 

 margin supporting two slender spines, and sometimes a third 

 much smaller one. The fifth pair of feet in the male is not much 

 unlike that of T. Clausii, but the terminal claw of the right side 

 is dilated and bulbous at the base. Length 1 '3 mm. 



Eurytemora affinis appears to be a very widely distributed 

 species, and sometimes occurs in immense profusion, constituting, 

 it is said, at some seasons the almost exclusive food of certain 

 fishes, as of the Shad in the Rhine and the Herring in the 

 Ealtic. Poppe has found it in many places in North Germany, 

 both in fresh and brackish water, Nordquist records either the 

 type or the varieties described by him under the names hirun- 

 doides and hispida from Helsingsfors in the Gfulf of Finland, 

 and from near Abo, at the entrance of the Gulf of Bothnia. 

 M. Gadeau de Kerville has taken it in the Estuary of the Seine, 

 and Herrick records a form either identical with or closely allied 

 to E. affinis from the coast of Alabama. 



In England E. affinis seems to be less common than the pre- 

 ceding species E. Clausii, but occurs in precisely similar locali- 

 ties. I have taken it in pools near Hartlepool Slake, county 

 Durham ; at Burgh Marsh, near Carlisle ; and Beaulieu Lake, 

 Hants. The Rev. Dr. Norman has sent me specimens from 

 Swan Pool, Falmouth ; and Mr. Thomas Scott has taken it in 

 the surface-net in the Firth of Forth, near Alloa. My friend 

 Mr. Isaac C. Thompson, F.L.S., of Liverpool, tells me that he 

 found it plentifully in tow-not gatherings from the river Mersey 

 in 1886, but has not taken it again until the present season 



