256 Mr. Baird on British Entomostraca. 



nous tail of the preceding, being rounded and slightly serrated 

 on the inferior margin. The rami are plumose, but not so 

 decidedly as in the preceding species. The head is obtuse, 

 much smaller than in Pulex, and the beak less projecting. The 

 sixth segment of the body has one or two slight projections 

 upon it, but is not provided with the lobules of the Pulex. The 

 shell is smooth and transparent. It is smaller than the prece- 

 ding species. 



III. Dapknia reticulata (plate ix. fig. 14.). Valvulis rotundatis, reticularis, 

 brevi-caudatis, capite parvo. 



Hab. Ponds and ditches round London, ditch near Surrey Zoological 

 Gardens, &c. 



Syn. Daphnia quadrangula. Mutter, Entomostraca, 1785.— -Mon. qua- 

 drangula. Linnceus, Syst. Nat. no. 24. 2999, 1788. — Mon. quadran- 

 gularis. Manuel, Encyc. Meth. t. vii. p. 723. no. 17. pi. 265. fig. 8, 9. 

 1792. — Mon. quadrangulus. Fabricius, Ent. Syst. t. ii. p. 492, 1793. — 

 Daphnia quadrangula. Latreille, p. 227. t. iv., 1802. — Daphnia ro- 

 tunda ? Straus, op, cit., 1821. — Mon. reticulatus. Jurine, p. 139. pi. 14. 

 fig. 3. 4, 1820. — Daphnia reticulata. Detmarest, p. 374, 1825. 



The valves of the shell in this species are nearly rounded, 

 reticulated, provided with a short tail. The head is small and 

 has no beak; the rami are not plumose. The figures of 

 D. quadrangula, Muller ; D. rotunda, Straus ; and Mon. reti- 

 culatus, Jurine, all differ somewhat in appearance ; but I have 

 seen this species frequently assume the appearance of Muller's 

 figure as well as that of Straus, and I have no doubt of all 

 these being the same species. 



IV. Daphnia cornuta (plate ix. fig. 15.). Valvulis convexis, curti-caudatis, 

 capite longe rostrato, ramis curtis. 



Hab. New River, London. 



Syn. Monoc. cornutus. Jurine, p. 142. pi. 14. fig. 8. 9. 10, 1820. — 

 Daphnia cornuta. Desmarest, p. 375, 1825. 



This little species is provided with a very long beak, which 

 is slightly curved. The anterior, inferior angle of the shell is 

 prolonged into a short tail. The rami are very short, scarcely 

 the length of the beak. In many respects it bears a strong 

 resemblance to a Lynceus, and seems to be the connecting 

 link between the two genera. 



