BELONOnfG TO DAPHNIA AND OTHER ALLIED GENERA. 231 



,f' :^.- ~"" of growth is the vertex produced 



/' " •:, into a spine, though there may 



«^- \ sometimes be observed a small 



tooth at the antero-dorsal angle. 



^ Length, 3 millimetres. 



The specimens here described 

 :/ \ were taken by the Eev. Canon 



'^J; IN'orman in Loch Rutton, Kirkcud- 



brightshire, and might almost, 

 from their very marked charac- 

 % ters, claim to rank as a distinct 



I species. Professor Gr. 0. Sars, 



I however, has named, but not des- 



I cribed, several varieties, and this 



! seems to agree with M, Richard's 



„ g figure and description of the 



hayhnia longispina, O. F. Miiller, variety major. 



var majoi% Sars, x 10. 



Var. aquilina, O. 0. Sars, (PL X., figs. 9, 10). 



1863. Daphnia aquilina, GO. Sars, Zoologisk Reise i Christi- 



anias og Trondhjems Stifter, p. 24. 



1890. ,, lacusfris, var. aquilina, Sars, Oversigt af 



Norges Crustaceer, etc., p. 33. 



The original description of D. aquilina is, as follows: — "D. 

 lacustri perquam affinis sed diaguoscenda margine inferiore 

 capitis incisuram profundam acutangulatam formante rostroque 

 acuminato et valde prominente rostri aquilini instar retro cur- 

 vato, testa a latere visa rotundato-ovata spinaque brevissima et 

 debili. Animal colore obscure- cseruleo saturato insigne. Longit. 

 circit, 2\ mm." 



In his recent revision Professor Sars adopts his specific name 

 as a varietal name only. I am not by any means sure that the 

 form here figured, from specimens taken by Mr. Thomas Scott, 

 in Loch Arklet, Perthshire, is actually identical with the aqui- 

 lina of Sars, but the head at any rate is very closely similar. 



