CRUSTACEANS 



but speaks of Koch's rostrata as hovering between the genera Alonella zn^ 

 Alona, using however for the latter genus the preoccupied nzme^ Lynceus. 

 Alonella nana (Baird) is reported from Keston by Mr. Scourfield. As its 

 length is given by Norman and Brady at xhs of an inch/ one may credit 

 their statement that it is the smallest of our British Cladocera, as also 

 Lilljcborg's that it is the smallest of the Swedish. Graptoleberis testudin- 

 aria (S. Fischer) by its coarsely reticulated valves justifies the generic 

 name of ' scribble-skin.' Its specific name indicates its likeness on a 

 very diminutive scale to a tortoise, the effect being produced in a lateral 

 view by the arched upper or dorsal margin of the valves and the broadly 

 protruding rostral part of the head. The species was taken by Mr. 

 Scourfield at Keston, who at the same place obtained Peracantha truncata 

 (O. F. Miiller). This I have myself taken at Tunbridge Wells. It may 

 be of use to remember that in this family the second antennae have both 

 branches three-jointed, whereas in the other three families one branch is 

 four-jointed, the single genus Bosminopsis excepted. 



The Ostracoda offer a study in some respects more difficult than that 

 of the Cladocera, inasmuch as the valves are little or not at all transparent 

 and are capable of tightly shutting in the whole body. Of the two tribes 

 now accepted, Myodocopa and Fodocopa, the former are marine and 

 have not as yet attracted attention in the sea about Kent. Of the latter, 

 which include a very large number of freshwater forms, many have been 

 recognized in this county. The local species are distributed among two 

 out of the five families of this division, the Cyprididae and Cytheridae. 

 Belonging to the first of these are the following species of seven genera. 

 Cypris fuscata (Jurine) is reported by Mr. Scourfield from Chislehurst, 

 is found in ponds near Tunbridge Wells, and is one of the most abundant 

 British species. C. incongruens, Ramdohr, which includes C. aurantia 

 Qurine), so named from the orange tints of its valves, has been found in 

 Kent by Professor Rupert Jones and is recorded by Baird from Black- 

 heath and Dover." C. virens (Jurine), common in small ponds and 

 ditches everywhere, has been taken by Mr. Scourfield at Chislehurst and 

 by myself near Tunbridge Wells. Cypria ophthalmica Qurine) is reported 

 by Mr. Scourfield from Keston, Gravesend, and Orpington. Brady and 

 Norman speak of it as ' one of the commonest of British species, occur- 

 ring everywhere in ditches, ponds, and lakes, both freshwater and 

 brackish.^ In 1868 Dr. Brady was happy to have found one male 

 specimen of this species. In 1896, however, he and Dr. Norman give 

 ' males common ' as a characteristic of the genus Cypria^ but of Cypris 

 they say, ' until quite lately males in this genus were unknown ; and up 

 to the present time no male has been found in the British Islands.' * 

 Cyclocypris serena (Koch) is recorded by Scourfield from Chislehurst, and 



» Natural History Trans. Northumberland, etc., 397 (1867). 



' See G. S. Brady, Monograph of recent British Ostracoda, in Trans. Linn. Soc. London, xxvi. pt. 2, 

 363 (1868). A reference to this valuable monograph may be understood for localities of Kentish 

 Ostracoda here quoted, when no other authority is specified. 



' Transactions Royal Dublin Society, ser. 2, iv. 69 (1889). 



♦ Loc. cit. ser. 2, v. 719, 720 (1896). 



255 



