446 D. J. SCOURFIELD, SYNOPSIS OF THE KNOWN SPECIES OF 



In the south and east of England I have only seen it from 

 Fleet in Hampshire, but it is not uncommon in the Lake District 

 and in Scotland. It has also been seen in Wales and Ireland, 

 and it occurs on the Continent, as I have collected specimens in 

 the Achen See in the Tyrol. 



Monospilus Sars. 

 M. dispar Sars. 



M. temiirostris Norman & Brady (17), Hodgson (10). 

 A rare species. Not yet seen in Wales. 



Anchistropus Sars. 



A. emarginatus Sars. 



One of the rarest of all the British Oladocera. It was found 

 by Mr. T>. Robertson in 1863 in the Paisley Canal near Glasgow 

 (see 17). It was not seen again, so far as I can ascertain, until 

 Mr. Kane two or three years ago took a few specimens in Lough 

 Erne. In 1901 mv friend Mr. C. J. H. Sidwell found two or three 

 specimens in one of the reservoirs of the East London Water- 

 works at Walthamstow, and last year I took a single specimen 

 (ephippial female) from the same place. 



POLYPHEMIDAE. 



Polyphemus O. F. Mliller. 

 P. pediculus (Linn.). 



Bythotrephes Leydig. 

 B. longimanus Leydig. 



B. cederstromii Beck (3). 



This has never been seen anywhere in the south and east of 

 England, but usually occurs, though never in large numbers, 

 in the lakes of the Lake District, North Wales, Scotland, and 

 Ireland. 



B. cederstroemii Sehoedler. 

 B. borealis Kane (13). 



