100 BRITISH ENTOMOSTRACA. 



The figure which Miiller gives of this species repre- 

 sents the head rounded ; that of De Geer, with a sharp 

 point. 



Miiller says, " variat fronte cornuta, cornu perpendicu- 

 lariter erecto." 



Jurine figures it with the rounded head, and finds fault 

 with I)e Geer's figui'e, which, he says, " does not appear 

 to me to be correct, since it presents the nasal prolonga- 

 tion of the shell curved forwards, in place of it being 

 downwards. That of Midler is better in this respect, 

 although it is not perfect." 



In the month of August 1841 I found, in the neigh- 

 bourhood of Isleworth, this species very frequently with 

 the sharp-pointed head ; and I observed, that all those 

 which came under my notice having the ephippium upon 

 them, possessed the rounded head. Among them, how- 

 ever, I found several with this form that had young in 

 the ovary, and no ephippium. As in the same pond there 

 occurred many individuals, both with the sharp and the 

 rounded head, and as at the same time they did not vary 

 in any other respect, I can only consider them as varieties. 



Var. a. Acute rostrata. Head terminating in a sharp 

 point directed upwards (t. X, f. 3). 



Var. (5. Ohtme rostrata. Head rounded superiorly 

 (t. X, f. 2). 



Hab. — Ponds about Isleworth, &c. ; from June to 

 October. 



Getms 2 — Moina. 



Head rounded and obtuse. Superior antennae of con- 

 siderable length, one-jointed, arising from the front of the 

 head, near the centre. Inferior antennae very large, and 

 fleshy at the base. 



