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Show 1893.] DR. C J. FORSYTH MAJOR ON MIOCENE SQUIRRELS. 187 systematic Zoology should not take into consideration, more than has been the case hitherto, the characters of the skull and dentition of Sciuromorpha, which characters have been of such excellent service for Myomorpha. M y arrangement of the Sciurida? (see the table, p. 189) contains three subfamilies: - 1. Sciurinee, including the genera of the subfamily Sciurinee of authors (with the exception of the Flying-Squirrels and some pigmy forms), as well as the members of the subfamily Arctomyince (Cynomys, Arctomys, Spermophilus). 2. Pteromyinas, including all the Flying-Squirrels (Sciuropterus, Pteromys, Eupetaurus). 3. Nannosciurince, the Oriental Pigmy Squirrels Sc. ex'dis, S. Mull., Sc, melanotis, Mull. & Schleg., Sc, concinnus, Thos. Sc. whiteheadi, Thos. % as well as the Ethiopian Pigmy Squirrel, Sc, minutus, D u Chaillu. I shall say a few words on the Pteromyince when dealing with the fossil forms. As to m y subfamily Sciurinee, the inclusion]of the Arctomyince in the subfamily Sciurinee, which appears at first sight to be a radical change, will, I am sure, meet with the least opposition. The close relationships of Spermophilus to Tamias and Sciurus are generally recognized ; and m y scheme is further justified by the consideration that several North-American species of the heterogeneous genus Spermophilus show in their skull and dentition a striking analogy with Xerus, a circumstance which has been generally overlooked. Besides, the dentition of the Arctomyince is so decidedly Sciurine that I do not see why we should any longer keep Arctomys and Spermophilus artificially separated from Xerus and Sciurus, for no ofher reason than convenience. As to the minor divisions, it results from the preceding remarks on the dentition of Sciurinee that the Ethiopian Xerus occupies, with its three species, a much less isolated position than has hitherto been admitted, inasmuch as numerous species of Ethiopian Squirrels, as well as some Oriental forms, included in the genus Sciurus, have close relations to Xerus in characters, which at the same time approach it to the Hystricomorpha. The characters of the skull of Xerus and its congeners point in the same direction, and consist, to express it briefly, in the elongate form of the cranium in general and the frontals particularly, coupled with the shortening of the postorbital processes ; whereas the remnant of Sciurinee are, on the contrary, characteristic for their broad frontals and the long postorbital processes. Moreover, a small group of Ethiopian Squirrels, related to Xerus (Sc. stangeri, Se, ebii, Sc, 1 Ann. Mag. Nat. Hist,, Nov. 1888, pp. 407, 408. Hab. Isabella, Philippines. 2 Ann. Mag. Nat. Hist. (5) 1887, xx. p. 127; P. Z. S. 1889, p. 231. Hab. Borneo. |
