100 
BRITISH ENTOMOSTRACA. 
The figure which Muller gives of this species repre- 
sents the head rounded ; that of De Geer, with a sharp 
point. 
Muller says, “ variat fronte cornuta, cornu perpendicu- 
lariter erecto.” 
Jurine figures it with the rounded head, and finds fault 
with I)e Geer’s figure, 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 Muller 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. j3. Obtuse rostrata. Head rounded superiorly 
(t. X, f. 2). 
Hah . — Ponds about Isleworth, &c. ; from June to 
October. 
Gems 2 — Mqina. 
Head rounded and obtuse. Superior antennae of con- 
siderable length, one-join ted, arising from the front of the 
head, near the centre. Inferior antennae very large, and 
fleshy at the base. 
^ /3. r ^ 
* £ Az tAa ^ e-rv-Mrt. y 
