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Show 1876.] MR. E. R. ALSTON ON THE ORDER GLIRES. 69 Of the seven well-marked families into which this section may be divided, the typical one, the Muridee, comprises a great number of genera. The best classification of these with which I am acquainted is that of Dr. Peters, which is here adopted with some little modification, his groups being ranked as subfamilies, and a slight alteration being made in their arrangement*. M. A. Milne-Edwards having clearly proved that the genera Ellobius and Siphneus really belong to this familyf, the subfamily Siphneinee is now placed alongside of the Arvicolincx, with which it is so nearly allied. Of the other families, the Myoxidce bear a very strong outward resemblance to the Sciuromorpha, which, however, is not markedly confirmed by their anatomy. Dr. Peters having shown that Plat acanthomys must be removed to the Murida%, the remaining genera of Dormice are all very closely allied, and are isolated from all other known rodents by the complete absence of the caecum. The next family, Lophiomyidee, contains a single form differing in structure not only from all the rest of the order, but even from all the known members of the mammalian class §. Nevertheless, if the extraordinary development of the temporal and malar regions be overlooked, the whole skull of Lophiomys is truly murine in type; and this is confirmed by all the other more important points in its anatomy. It is strange that, although its habits appear to be at least partly arboreal, Lophiomys should differ from all the rest of the section in the incomplete development of its clavicles. The Spalacidee, even when disencumbered by the removal of Siphneus and Ellobius, are still divisible into two subfamilies-the typical Spalacinee, which have the normal mandible of the section, and the Bathyergince, in which are found the hystricine characters already mentioned (supra p. 68), and which were hence named Spa-laces subhystriciformes by Prof. Brandt. The next family, which includes the American rodents with cheek-pouches which open outside the mouth, was founded by Mr. Waterhouse under the name of Sacco-myidee, and subsequently divided by Prof. Baird into two subfamilies, Geomyinee and Saccomyinee. Dr. E. Coues, in a recent valuable memoir, has contended that these latter divisions should rank as separate though allied families||-a view in which I cannot agree. The diversity in their outward form may be paralleled by that in the Squirrels and Marmots ; and the differences in their cranial structure are, as Dr. Coues himself observes, of a superficial nature. In any case, Mr. Waterhouse's name must be changed; for Dr. Peters has shown1*-!! that the genus Saccomys of Frederic Cuvier is in all probability, a synonym of Desmarest's Heteromys. The oldest and best- * The names only of these divisions appeared in the Monatsb. Ak. Berlin, 1866, pp. 13, 14.; for access to Dr. Peters's hitherto unpublished characters I am indebted to the courtesy of the author. t Recherches pour servir a l'Hist. Nat. des Mammiferes, pp. 71-129. | P. Z. S. 1865, pp. 397-399. § Cf. A. Milne-Edwards, Nouv. Arch, du Mus. iii. pp. 81-118. || Rep. Explor. Colorado River, p. 215; Bull. U.S. Survey of Territories 2nd ser. no. 2, pp. 81-90. f Monatsb. Ak. Berlin, 1874, p. 354-359. |