CRUSTACEANS 



company of specimens from the dried mud examined last year included 

 three species of Cladocera and two of Ostracoda. Of those which 

 have reappeared this spring, one of the Ostracoda species is now in the 

 ascendant. 



Of the Cladocera, or branching-horned Entomostraca, so-called from 

 their two-branched second antenna?, there are in Surrey several species 

 well adapted to gratify the microscopist, and to direct the attention 

 of collectors and students in general to the divisions and subdivisions 

 of this important group. There are two principal sections. In the 

 first, which is also the more extensive, the feet are pretty well covered 

 by a bivalved carapace. This section contains two tribes, the Cten6poda, 

 called ' comb-footed,' from the comb-like arrangement of setas on their 

 six pairs of similar feet, and the Anom6poda, in which, as the name 

 implies, the feet are not all similar. The former tribe contains two 

 families, one of which, the Sididae, is here represented by Sida crystallina 

 (O. F. Miiller), recorded by Baird from a 'ditch near Richmond, oppo- 

 site Isleworth,' 1 and by members of the Quekett Microscopical Club 

 from Walton, Woking and Richmond Park. 2 In the same family, and 

 also taken by Baird from a ' ditch near Richmond, opposite Isleworth,' 3 

 stands Daphnella wingii, which has large eyes and very large antennae, 

 but a tail that is by comparison tiny. The proper generic name is 

 Diaphanosoma, in agreement with the ' beautiful, clear, crystalline trans- 

 parency ' of its carapace, and perhaps it should be called D. brachyurum 

 (Lievin), the short-tailed Diaphanosoma, but about this there is some 

 uncertainty, so that with an alternative perhaps it may have to be 

 distinguished as D. wingti. 



The tribe of the Anomopoda contains four families. The first of 

 these is the Daphniidas, a powerful clan, in numbers numberless, so 

 predominant as a rule in the horse-pond that it can scarcely fail to 

 make the horse willy-nilly a carnivorous animal. Among the speci- 

 mens reared from the dried mud above mentioned those assignable to 

 Dapbnia were however not very numerous. They were small, with the 

 surface reticulation during life very conspicuous, the terminal spine of 

 moderate length, and the abdomen dorsally not strongly sculptured. 

 The species appear to be Dapbnia longispina (O. F. Miiller). Possibly 

 in youthful stages many of their kindred fell victims to the better pro- 

 tected Ostracoda. Apart from this private hatchery there are records 

 showing that more than one species of Dapbnia or its nearest kindred are 

 to be found in Surrey. Thus in a paper on ' Pond Life ' Mr. W. Low 

 Sarjeant, speaking of Mitcham Common, says: 'Just after passing the 

 windmill there is a large duck-pond, which in the autumn especially 

 swarms with a giant race of Dapbnia, many of them exceeding an eighth 

 of an inch in length, and I have taken them three-sixteenths of an inch 



1 British Entomostraca, Ray Soc. p. 109 (1850). 



3 Journal of the Q. M. C. ser. 2, vol. ii. p. 191 (1884) ; vol. iv. pp. 171, *73, 326 (1888, 

 1889). 



3 British Entomostraca, p. 1 1 o. 



I 193 



