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Show 1897.] MALAGASY GENUS BRACHYUROMYS. 703 3. Siphneus.-Oerrit Miller has recently expressed the opinion that it may eventually prove necessary to unite the " Siphnelnce," i. e. Siphneus and Ellobius, with the Microtince l. This corresponds fairly with Alphonse Milne-Edwards's views, who has considered the " Slphnes" to be " des Arvicoles anormaux."2 O. Thomas maintains the subfamily for Siphneus alone, since according to his view its " differences, both external, cranial, and dental, are clearly sufficient to demand separate subfamily rank."3 It is to be remarked that Winge has treated the question of the relationship of Siphneus exhaustively many years ago. Whilst uniting Ellobius with the Microtince, he considers Siphneus to be a lower type, and accordingly places it wdth the Crlcetlnas; its resemblance with the Voles resting solely on their having open roots to the molars, which otherwise are not different from the "Hesperomys-tyve." H e points out that no Vole has such a small m. 1 inf., with not more than the usual five loops. Winge shows besides, that Siphneus lacks the powerful crest in the wall of the temporal fossa, which gives the characteristic feature to the Microtine skull, whereas tbe temporal muscles are inserted on the surface of the skull in the same manner as in the Griceti; and that the basioccipital region and the centrum of the basisphenoid are broader, the tympanic bones smaller, than in the Voles 4. In the more simple structure of the molars he sees an indication of closer relationship with " Cricetulus." The shape of the outer wall of the infraorbital canal is said to be about as in the Hamsters ; likewise tbe zygoma and the crests on the cranium, only slightly stronger ; and equally the flattening and forward inclination of the occiput, the only difference being that these characters too are more strongly developed than in the Hamsters 5. It seems to me that there is little to object to Winge's view of the question; I would even go a little farther still. In his arrangement of the Muridae8, Winge opposes his Rhizomyini (i. e. Cricetodon, Eumys, Rhizomys) to the rest of the Muridae, m. 1 in the former being only slightly larger, in the latter considerably larger than m. 2. As regards this character, Siphneus certainly belongs to the former group, with more right than Cricetodon and Eumys, which both herein are scarcely different from the Hesperomyes. In pattern and size the two anterior molars of Siphneus agree as much with each other as they do in Spalax, Tachyoryctes, and 1 Gerrit S. Miller, " Genera and Subgenera of Voles and Lemmings" (North- American Fauna, No. 12, p. 8, footnote 3). Washington, 1896. 2 H. Milne-Edwards et Alph. Milne-Edwards, ' Recherch. p. servir a l'Hist. nat, des Mammiferes etc.,' t. i. Texte. pp. 76-79, Paris, 1868-74. 3 O.Thomas, "On the Genera of Rodents " (P. Z. S. p. 1021 footnote 1). London, 1896. 4 This does not bold good, however, with regard to all the genera of Microtince, e. g. Fiber and Ellobius. 3 H. Winge, " O m gra-ske Pattedyr " (Videnskab. Meddel. fra d. Naturh. Foren. Kjobenhavn for Aaret 1881, pp. 47-49. Kjobenhavn, 1882; see also H. Winge, ' Gnavere fra Lagoa Santa,' pp. 124,125, 126). 0 'Gnavere fra Laeoa Santa,' p. 125. 46* |