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Show 434 MR. O L D F I E L D T H O M A S ON TMay 4, Boror specimens proved to be, Senna and Tette were the localities first named by him. In a previous communication to the Society', M r . Thomas bad stated that in Petrodromus there was a considerable difference in size between the sexes; but this statement he had now to withdraw, as it proved to have been based on a confusion of species, and a careful comparison now showed that there was no essential difference in size or in other characters between the two sexes. In confirmation of this it might be noted that as regards the allied genus Macroscelides, of 15 skulls of M. fuscus from Mashonaland and Matabililand, there seemed no appreciable difference in size between the two sexes. Similarly there appeared to be no differences between the sexes as regards the character of the hairs on the under surface of the tail, peculiarities wdiich were first described by Dr. Giinther2 and then by Dr. Matschie3; and these had been, especially by the latter, regarded as in some way connected with sex. Now, however, it appeared that both sexes possessed tail-like bristles of the same nature, and that the structure of these formed very good specific characters. The following were diagnoses of the three species recognized by Mr. Thomas :- 1. P. TETRADACTVLUS, Pet. Tail well-haired, the hairs perfectly simple and normal, not swollen, but more numerous than in the other species, hiding the scales ; terminal half of tail markedly black, A small part of the rump around and above the base of the tail naked. Skull of medium size. Large and open posterior palatal vacuities present. Hab. Zambesi and Shire Rivers; Senna and Tette (Peters); Zomba and Milanje (Whyte). 2. P. ROVUMcE, sp. n. Tail much more thinly haired, the hairs not hiding the scales, and more uniformly coloured, brownish above, rather paler below. Along the middle of the underside there are a number of peculiar broadened bristles, about 2 m m . long, thin basally, thickened at their middle, and tapering terminally to a point. These thickened bristles are mostly wdiite basally and black terminally. Rump largely naked, a space of half an inch laterally from the tail, the whole of the back of the hams, and a mesial extension halfway along the sacrum being entirely bare, or with a thin covering of fine silky white hairs, so fine as to be quite invisible without a lens. Skull very similar to that of P. tetradactylus, but rather smaller and narrower across the brain-case. 1 P.Z.S. 1890, p. 445. 2 P.Z.S. 1881, p. 164. 3 Saug. Deutsch-O.-Afr. p. 29 (1895). |