244 ON THE BRITISH SPECIES OF ENTOMOSTKACA 



different from those of the adult D. magna, and I at first belieyed 

 that I had got hold of an undeseribed species. But, knowing 

 that my friend Dr. Norman had taken a gathering from the same 

 place and at the same time (at the Field Club Meeting of May 

 26th, 1865) I asked him if he could supply me with further 

 specimens. This he kindly did, and I fortunately found amongst 

 them a fully-developed male of the normal type. Had I not 

 done so I might possibly have remained under the impression 

 that the Plessey animal belonged to another species altogether. 

 I have figured the antennules and caudal laminae (figs. 7, 8), 

 which I believe to belong to immature males of D. magna. It 

 will be noticed that the tactile (?) lobe of the caudal lamina is 

 not developed, but that its place is occupied by a series of spines 

 similar to those of the adult female, and though the stem of 

 the antennule is well grown — showing that the specimens are 

 undoubtedly males — its terminal sensory hairs are altogether 

 different in character from those of the adult. 



[Daphnia ])sittacea, Baird, (Brit. Entom,, p. 92, Tab. IX., 

 figs. 3, 4), is quite unknown to me, though noted by some con- 

 tinental authors]. 



Genus MOII^A, Baird. 



Yalves quadrangular with rounded angles. Head rounded, 

 without a rostrum, separated from the body by a distinct con- 

 striction. Antennules very large, fusiform, bearing in the middle 

 a long seta. Post-abdomen fringed with numerous ciliated teeth. 

 No eye-spot. 



Moina rectirostris, (0. F. Miiller). Fig. D. 



1785. Baplmia rectirostris, 0. F. Miiller, Entomostraca, p. 92, 



tab. XII., figs. 1-3. 

 1820. Monoculus rectirostris, Jurine, Histoire des Monocles, 



p. 134, pi. V.3, figs. 3,4. 

 1850. Moina rectirostris, Baird, British Entomostraca, p. 101, 



pi. XL, figs. 1, 2. 



Female. — Seen from the side the outline of the valves is 

 subquadrangular, with rather irregularly sinuous margins and 



