CRUSTACEANS 



Chirocephalus diaphaiius, Prevost, in pools on Blackheath, a locality 

 which, if now in the county of London, in those days belonged to Kent. 

 This species, though very similar in structure to the Apus, is through 

 the absence of the shield very different in appearance. Also its eyes 

 are stalked instead of sessile, and its feet are reduced to the more 

 moderate number of eleven pairs. The second antennae of the male 

 form large claspers, thus accounting for the generic name which im- 

 plies that the head is furnished with hands. The specific name 

 alludes to the beautiful translucence of the animal. Its eggs, like 

 those of many other freshwater Entomostraca, can remain a long time 

 in dried mud without losing the capacity of developing subsequently 

 in water. 



The Cladocera, a second subdivision of the Branchiopoda, are 

 named from the branching second antennae which are their locomotive 

 appendages. They furnish the fresh waters of all counties with 

 numerous species. In Kent about a score of species have been 

 catalogued, several of them quite recently through the assiduity of Mr. 

 D. J. Scourfield, editor of the Journal of the Quekett Microscopical 

 Club. It happens that all these species are included in one tribe, called 

 the Anomopoda because they have their five or six pairs of feet not all 

 alike, the first two pairs being, in contrast to those which follow, more 

 or less prehensile and without branchial laminae. The tribe is divided 

 into four families, among which the known Kentish species are repre- 

 sented as follows. The family Daphniidae no doubt contributes 

 Daphnia pulex (de Geer), since that species, according to Baird ' lives in 

 almost all pools, and ditches of standing water, round London, etc." 

 But this commonest of species is not free from perplexities, as will be 

 seen by those who study the synonymy in Lilljeborg's great work on the 

 Cladocera of Sweden. Baird establishes two other species of the genus 

 D. psittacea from ' Pond on Blackheath ' and D. schoefferi from ' Pond on 

 Bexley Heath, Kent, August and September, 1849.'' In addition to 

 these D. obtusa, Kurz, is reported from Keston by Mr. Scourfield, and a 

 variety propinqua of the same species by Dr. G. S. Brady from the 

 neighbourhood of Tunbridge Wells. This variety was originally dis- 

 tinguished as a separate species by Professor Sars, who reared it out of 

 dried mud sent him from South Africa.' Baird's D. schoefferi is identi- 

 fied by Brady with the earlier D. magna, Straus, which he refers to a 

 new genus Dactylura, but this is cancelled by Lilljeborg, who identifies 

 Baird's species and that of Straus with the yet earlier D. pennata (O. F. 

 Miiller). As to Baird's D. psittacea, Brady says, it ' is quite unknown to 

 me, though noted by some continental authors.' * Lilljeborg confesses 

 to have confused it at first with Baird's later JD. atkinsoni, but now 

 describes and figures it under its own name, with the recognition that 

 Jules Richard had already distinguished it from £). atkinsoni in exemplary 



• British Entomostraca, p. 29. ' Loc. cit. pp. 93, 95. 



3 Brady, Nat. Hist. Trans. Northumberland, Durham, and Neuuastle-upon-Tyne, xiii. pt. 2, 225 (1898). 



♦ Loc. cit. 244. 



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