Page:VCH Kent 1.djvu/304

 A HISTORY OF KENT fashion. D. obtusa is regarded by Lilljeborg as nothing but one of the numerous varieties of Z). pulex, and since D. propinqua is described as ' in general character intermediate between D. pulex and Z). obtusa^ it scarcely needs a distinctive name. Brady says, ' I have seen but one male of this form. . . this has the short abdominal processes charac- teristic of D. obtusa^ and appears to be the prevailing form of Daphnia in Kent and Sussex. In the spring of 1897 I found it abundantly. . . in ponds at Bayhall, Tunbridge Wells.' ' The same family contains Shnocephalus vetulus (O. F. Miiller) found at Chislehurst by Mr. Scour- field and by myself at Tunbridge Wells, and two species of Moina, M. rectirostris (O. F. Miiller) and M. branchiata (Jurine), both recorded by Baird from a " Pond on Blackheath." ' ' Recently Shnocephalus vetulus has been renamed Simosa vetula by the Rev. Dr. Norman, its older generic name being preoccupied. Of the next family Bosminidae Mr. Scourfield reports Bosmina cornuta (Jurine) from Keston. By Lilljeborg this species is identified with the earlier longirostris of O. F. Miiller. In this family, it may be observed, the intestine is simple, and thereby it is distinguished from the Daphniidae, in which the intestine has in front two caecal processes, and from the Chydoridae, in which the intestine is looped. Unfortunately our third family, the Macrotrichidae, occasionally have the caecal processes and sometimes have a loop to the intestine, but often are devoid of these characters. By this inconstancy they seriously detract from the value of this internal apparatus as a help to classification. To the Macrotrichidae belongs Ilyocryptus sordidus (Lievin), found by Mr. Scourfield at Orpington. The species of this genus have neither the anterior caeca nor the median loop. While the habit of hiding in the mud is expressed by the generic title, the specific name sordidus intimates that the bearer of it does not escape the ordinary consequence of touching what is foul. This is not quite a matter of course with crustaceans, for some manage to emerge from mud with their coats exquisitely glossy, although the same mud clings to their dead bodies very tenaciously. The Chydoridae supply the county with several species. The ubiqui- tous little Chydorus sphaericus (O. F. Miiller) is reported by Mr. Scourfield from Hayes, Keston, Gravesend, Orpington and Chislehurst, and has also been found at Great Bayhall, near Tunbridge Wells. The slightly larger C. globosus, Baird, is reported by Baird from ' Pond near Bexley Heath, July.' ' The same author records his own Alona ovata from ' Pond on Blackheath, April 1848." Of the same genus Mr. Scourfield reports A. quadrangularis (O. F, Miiller) from Orpington, A. tenuicaudis, Sars, from Keston, A. rectangula, Sars, also from Keston, and A. guttata, Sars, from Chislehurst. The first of these five is exposed to a twofold doubt. Brady and Norman make it doubtfully a synonym oi A.rostrata (Koch). Lilljeborg in his ' Cladocera Sueciae ' takes no notice of Baird's ovata, > Brady, Nat. Hist. Trans. Northumhirland, Durham, and Nezvcastle-upon-Tynf, siii. pt. 2, 226 (1898). ' British Entomostraca, pp. loi, 102. > Loc. cit. p 128. « Lqc. cit. p. 133. 254