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Show 1878.] MR. E. R. ALSTON ON NEOTROPICAL SQUIRRELS. 661 Upper parts grey or reddish grey, the hairs black, tipped or ringed and tipped with white or red. Pelage somewhat soft, with a. good deal of under-fur; lower parts deep red, orange, or white. Tail black, washed with white, the hairs usually rufous at their base, with black rings and white tips. Under this name I feel myself obliged to bring together two Mexican Squirrels of which typical specimens are very different in appearance. Mr. Allen has kept them separate under the names of S. aureigaster and S. leucops, remarking that the difference in coloration leaves little doubt of their distinctness, but adding that " more abundant material may show that they are not specifically separable" (op. cit. p. 755). The colour-variation is not nearly so great as we shall find it to be in the next species ; and after a careful examination of a great number of specimens, especially of the fine series in the Paris Museum, I have been unable to find a single distinctive character which is constant. Typical specimens of the two forms may be thus described :- 1. The aureogaster type. Upper parts dark grey, the hairs black, finely tipped with white. Lower parts deep red, which is usually more or less washed over the grey on the shoulders and flanks. 2. The leucops type. Upper parts lighter grey, with a peculiar golden lustre, the hairs being finely ringed with bright rufous and tipped with white; nape and rump more strongly rufous. Lower parts bright red, orange, or white. Many specimens, however, which have the general appearance of aureogaster show the rufous subterminal ring of leucops on some part of the dorsal surface ; and in others we find the red nape and rump-patches gradually appearing. I am therefore compelled to return to the view long ago expressed by Isidore Geoffroy', and to regard them as varieties of the same species. With regard to distribution, all the specimens which I have seen with authenticated localities are from Mexico ; but Mr. Allen mentions one from Guatemala in the Washington Museum. Specimens in the British Museum are labelled as being from Columbia; but there can be little doubt that this is an error. S. aureogaster is stated by Prof. Sumichrast (as quoted by Mr. Allen) to be " the common species of Sciurus of the tierra caliente of the east coast" of Mexico; and both forms are found in the States of Oaxaca and Tehuantepec. Turning to the question of synonymy, I must briefly explain why I have retained Erxleben's name for this species. Mr. Allen considers it to apply rather to the next species, but rejects it altogether, on the ground that it is based partly on Buffon's "Coquallin" (S. niger, L.), and partly on the " Coztiocotequallin " of Hernandez. It is, however, primarily founded on the latter, Buffon's name being only quoted as a synonym ; and Erxleben's diagnosis and description appear to m e to be quite characteristic of the leucops form of the 1 Voy. de la Venus, Zool. pp. 156-163. |