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Show 90 DR. G. S. BRADY ON FRESHWATER [Feb. 2, slender of the two. The right valve is the smaller of the two, and has the dorsal margin less arched. The inner aspect of the valves shows a large shelf-like flange fore and aft. The terminal claws of the second pair of antennae are slender and finely pectinated on the inner margin. Postabdominal rami slender, with one long terminal claw, one short seta at the base of the claw, and one a little removed on the margin of the ramus. Margins of claws and ramus minutely pectinated. Shell thin, horny, of a smoky hue. (" Colour in life light-brown, with darker zebra-like markings." Prof. R. Tate.) Length ^ of an inch. Collected by Prof. R. Tate in fresh water, at Kangaroo Island, Australia. Though quite abnormal in shape of shell, the soft parts of the animal agree in every important respect with those of the genus Cypris. Genus CHLAMYDOTHECA, de Saussure1. " Testa undique pilosa, antice posticeque rotundata, appendice anteriore cum margine valvuloe dorsali sensim coalescente, cum mar-gine ventrali autem angulum manifestum efficiente; appendice posteriore minima. Altitudo maxima pone medium et propius ventralem quam dorsalem marginem sita, exinde pars postica crassior quam antica. Margo ventralis vix sinuata, dorsalis valde armata. Impressio muscularis paulo ante medium sita." The anatomical structure agrees exactly with Cypris. The author (de Saussure) refers to a paper by Sir John Lubbock, in which a similar species, Cypris brasiliensis, is described2. The genus Cypridea, Bosquet3, if not identical with, is at least very nearly allied to, the forms now under discussion. No undoubted recent specimens of Cypridea have, however, as yet been seeu, and Prof. Rupert Jones, in a recent paper " O n the Ostracoda of the Purbeck Formation,"4 says that the "hinder margin is definitely straight along the middle third or more of the dorsal edge, with the hinge-angles more or less defined, and is oblique to the main axis of the valve. The left valve is the largest, and receives the dorsal edge and a straight ridge of the other valve in grooves on its dorsal and ventral contact-margins." These characters are not to be found in Chlamydotheca. Moreover, from the figures given by Prof. Rupert Jones, it seems that both valves of Cypridea are provided with the notch and hatchet-like anterior process, whereas in Chlamydotheca only the left valve is so formed. 1 " Memoire sur divers Crustaces nouveaux des Antilles et du Mexique," par M. Henri de Saussure. (Memoires de la Societe de Physique et d'Histoire Natu-relle de Geneve, 1856.) 2 " On the freshwater Entomostraca of South America." (Trans. Entom. Soc. Lond. new series, vol. iii. part vi. 1855.) 3 " Entom. fossil, des Terrains tertiaires de la France et de la Belgique." (Mem couronnes Acad. Boyal de Belgique, vol. xxiv. 1852.) 4 " Ostracoda of the Purbeck Formation, with notes on the Wealden species." (Quarterly Journal of the Geological Society, August 1885.) |