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Show 390 MR. J. L. BONHOTE ON THE [Nov. 28, Mus plumbeus A. M.-E. Recli. Mamm. p. 138, pi. 43. tig. 2 (1874). Mus rattus flavipectus A. M.-E., Thos. P. Z. S. 1898, p. 772. This species is the representative of the rufescens-group of Mus rattus, which inhabits China. It is of moderate size, having the tail rather shorter than the head and body. Fur soft and destitute of spines. General colour above uniform yellowish brown, slightly lighter on the flanks. Hairs slate-coloured at their base, with ochreous tips, and intermixed among these are pure black hairs of a finer texture. Under parts varying from dirty yellowish to yellowish-white, often, but not invariably, showing traces of a white mark on the breast. The hind feet are whitish and the hands dark brown margined with white. Tail unicoloured and covered with hairs. Skull. The skull is that of a fairly typical Mus rufescens, and, except in its slightly smaller size, is indistinguishable from the Indian form*. Dimensions. Head and body 200 mm.; tail 160 ; hind foot 31 ; ear 18. Skull f . Greatest length 41 mm.; basilar length 36'5 ; palatilar length 20 ; diastema 11*5 ; length of incisive foramina 8 ; length of nasals 15; zygomatic breadth 20; interorbital breadth 6; breadth of brain-case 15*5 ; length of molar series 7. Habitat. The type of this species came from Moupin in W. Szechuen, but it also occurs at Kuatun in N.W. Fokien, Kiou Kiang in Kiangsi, and Foochow, so that it is probably widely distributed throughout the country. It also occurs in Formosa. This and Mus griseipectus are the common Rats of China. The difference in the colour of the under parts, as denoted in their specific names, will form to some extent a distinguishing character, although the under parts in flavipectus often become very light, and in old specimens of griseipectus may show a yellowish tinge. However, I am inclined to think this character unreliable, and a much better test is the greater size of griseipectus, as shown by the length of the hind foot and skull-measurements. In griseipectus, moreover, the tail, although it can hardly be called " bicolor," is distinctly lighter on its under surface, and this seems to be the only reliable external characteristic at all ages. In the description of M. flavipectus in the Recli. Mamm., M. Milne-Edwards adds a footnote to say that M. germaini from Pulo Condor closely resembles this species, especially in its coloration. Although approximately correct, it may be well to notice that M. germaini may be distinguished by its size, which * For careful figure of the skull of M. rufescens, see paper by the author, Fasc. Malayenses, Zoology, vol. i. pi. iv. fig. 3 (1903). f The measurements, which are the same as those taken in my former paper, are now called after Mr. O. Thomas's scheme for cranial measurements, published Proc. Biol. Soc. Wash. vol. xviii. p. 191 (1905), the alterations (in name only) being basilar and palatilar for basal and palatal. |
