A HISTORY OF SURREY 



in length, which is an enormous size for a Dapbnia.' 1 Judging by the 

 size alone it is tolerably safe to infer that the species intended is Dapbnia 

 magfia, Straus. Mr. D. J. Scourfield indeed has noticed that ' this, the 

 largest species of the genus, seems to be almost solely an inhabitant of 

 little duck-ponds.' But as the area of duck-ponds is apt to vary with 

 the drought or moisture of a season, the dimensions of the pond on 

 Mitcham Common need not be thought prohibitive. Among objects 

 found on the excursions of the Quekett Club D. schafferi is recorded 

 from Richmond Park, and though no authority is given this is doubtless 

 intended for the species so named by Baird, which is a synonym of D. 

 magna. Also the same club records from Richmond Park a ' Daphnia 

 male, very large, body 2 mm. long.' In correspondence with these 

 measurements M. Jules Richard gives 2-2*2 mm. as the length of the 

 male D. magna, and 4-5 mm. as that of the female. 2 Dr. Brady 

 has recently transferred this species to a new genus named Dacty/ura, 

 ' finger-tail,' in allusion to a finger-like lobe in front of the terminal 

 unguis ; but this is strictly an entail male, the female not having any 

 such finger-like lobe.* After a mention of Daphnia pulex another species 

 is rather vaguely described, among objects found by the Quekett Club at 

 Woking, as ' a Daphnia probably reticulata of Baird's British Ento- 

 mostraca having the eye at the end of a blunt rostrum.' 4 The D. 

 reticulata of Baird's work is now divided between two species, Cerio- 

 dapbnia reticulata (Jurine) and C. mega/ops, Sars, in this genus the first 

 antennae of the female being movable, whereas in the same sex of 

 Daphnia they are immovable. In the same family stands Moina recti- 

 rostris (O. F. Mu'ller), which is one of the species bred from the dried 

 mud taken at Headley. When alive this little transparent creature is 

 beautiful under a lens. The pink colour is visible even to the unaided 

 eye, but a slight magnification shows this to be due to the round pink 

 eggs, neatly arranged in two parallel series, three in a row. It is also 

 recorded from this county by Dr. Brady on the authority of Mr. Scour- 

 field. 6 



In the extensive family of the Chydoridae the waters of Surrey are 

 well provided with species. It has two belonging to the genus Chydorus, 

 Leach, which gives its name to the family. One of these, the very 

 small and very common C. spbcericus (O. F. Miiller), was bred from 

 the dried mud procured at Headley ; the other, C. globosus, Baird, 

 is recorded by Dr. Baird from a ditch near Richmond, with the obser- 

 vation that it is to be met with in 'June, July, August and September, 

 but rare, and confined apparently to small patches.' He describes it as 

 having the 'shell quite globose, a good deal resembling in form the 

 preceding species, but more completely rounded, and nearly six times 



1 Proceedings and Transactions of the Croydon Microscopical and Natural History Club, p. 8 (1884- 

 1886). 



2 Ann. Sci. Nat. ser. 8, vol. ii. pp. 193, 195. 



3 Nat. Hist. Trans. Northumberland, Durham, and Nttvcastle-ufon-Tyne, vol. xiii. pt. 2, p. 240. 



* Q. M. C. ser. 2, vol. ii. p. 34. 



* Nat. Hist. Trans. 'Northumberland, etc. vol. xiii. pt. 2, p. 245. 



194 



