| OCR Text |
Show 420 MR. G. E. H. BARRETT-HAMILTON ON [Apr. 3, 19. MUS SYLVATICUS LEWISI. Mus abbotti, E. T. Newton, Quart. Journ. Geol. Soc. vol. vii. pt. 2, no. 198 (May 1, 1894). Nee Mus abbottii, G. B. Waterhouse, P. Z. S. July 25, 1837, p. 77, which is a form of M. musculus Linnaeus. Mus lewisi, E. T. Newton, P. Z. S. 1899, p. 381. Type. A skull, being one of those collected by Mr. Lewis Abbott in the ossiferous fissure at Ightham, Kent, and now in the Geological Museum, Jermyn Street, London, S.W. Description (skull only). Similar to 31. sglvaticus, but differs from it in the absence of the anterior pointed tubercle of the first lower molar. Distribution. Known only from the typical series. General Remarks. The absence of a small dental tubercle seems to be a very small point on which to base a species, especially as the skulls of 31. lewisi were accompanied by others which were indistinguishable from those of 31. sglvaticus. But the validity of the specific character must depend on its constancy or inconstancy in skulls of modern sglvaticus. I have examined 49 of these with a view to deciding this point, with the result that in 47 the tubercle in question is conspicuously present, while in two only (viz., no. 98.2.2.22, from Cintra, Portugal, and no. 95.10.25.1, from Lewis, Scotland, the type of Mus. s. hebridensis) had the wearing down of the teeth made it indistinct. The specimens were of all ages, with the teeth both worn and unworn, and from widely different localities, yet in all the tubercle shows clearly, and must therefore, I think, be considered characteristic of present day sglvaticus. W e cannot tell what external features were present in 31. s. lewisi in correlation with this slight peculiarity of dentition. These may have been conspicuous, or they may have been nonexistent. The material in our hands permits us merely to examine the skulls, and from them alone, according to m y treatment of 3Ius sylvaticus, I can only admit 31. lewisi to subspecific rank as representing a side development of the 3Ius sglvaticus stock. MUS ARGENTEUS. 3Ius argenteus, C. J. Temminck, Faun. Jap. p. 51, pi. xv. fig. 1 (1845) (on the date of this work see Sherborn & Jentink, P. Z. S. Feb. 19, 1895, p. 149). Type locality. Japan. Distinguishing Characteristics. Resembles Mus sylvaticus in arrangement of colours, but has the upperside of a peculiar, deeper, more uniform M. minutus-hke red, of a shade that I have never seen in M. sylvaticus. In the specimens at m y disposal there is no breast-band and none of the black-tipped hairs of M. sylvaticus. The size is that of 31. musculus. Temminck states that the general size and the ears of M. argenteus are as in M. musculus, and the tail is longer than the head and body. Of the colour he writes that " tout le dessus du corps, jusqu'a la |
