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Show 1894.] MAMMALS OF NYASALAND. 139 11. PETRODROMUS TETRADACTYLUS, Pet. a. Ad. sk. 3. Zomba. 1/6/93. 12. FELIS SERVAL. a, b. 1mm. sks. 3 2 • Fort Johnston. 2/93. 13. HYAENA CROCUTA, Erxl. a. Ad. 3 skin and skull. Zomba. Sept. 15, 1893. The following are the dimensions of the skull: -Basal length 233 mm.; extreme length 286 ; zygomatic breadth 179. 14. EHYNCHOGALE1 MELLERI, Gray. Rhinogale melleri, Gray, P. Z. S. 1864, p. 575 ; Thomas, P. Z. S. 1882, pi. iii. a, b. Ad. sks. 3 $ . Eesidency Garden, Zomba. 4/93. c. Tg. al. Ditto. " Wild fruits are always found inside the stomach of this Mungoose."-A. W. The discovery of this fine Mungoose in Nyasaland is of considerable interest for two reasons. Firstly, its locality nowbecomes known with certainty, whereas hitherto it has been only conjectured2 to occur on the Zambesi, a supposition that now proves to have been well-founded. Secondly and chiefly, owing to the fact that the original, and hitherto unique, specimen presented the remarkable number of five premolars on each side above, further specimens were urgently needed to show whether or not this was the normal number in the species. The importance of this point is exceedingly great, for no other known mammal has more than four premolars, and the exception presented by Rhynchogale has puzzled myself and other writers on the subject3. Believing as I do that four is and always has been the maximum number of premolars normally present, at least since middle Mesozoic times, it is something of a relief to find that the one known exception to this rule now disappears, as the perfect skull of specimen a4 has simply the normal number of four premolars, and we may consequently assume that the type was abnormal in its possession of five. The occasional abnormal development of five premolars is well known in Carnivores, notably in dogs, and is, I believe, generally due to the fission into two of one or other of the normal set of four. I quite fail to see, as Mr. Bateson would have us do5, that such cases are any argument against a belief in the individual homologies of teeth, and are not explainable by the simple process, discovered and described by himself, of the fission of normal teeth. 1 Nom. nov. = Rhinogale, Gray, P. Z. S. 1864, p. 575; nee Gloger, Handb. Naturg. pp. xxix and 75 (1842). 2 P. Z. S. 1882, p. 86. 3 Cf. Phil. Trans, vol. 178, Biol. p. 456, 1887 (footnote). 4 Specimen b is so old that the teeth are all worn down or broken out, while specimen c is too young to show any teeth at all. 5 P. Z. S. 1892, pp. 102 et seqq. |