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Show 70 MR. E. R. ALSTON ON THE ORDER GLIRES. [Jan. 18, known genus will therefore legitimately give name to the family Geomyidee, the subfamilies standing as Geomyina. aniHeteromyina. Here I am inclined to place, at least provisionally, a family ot Rodents which flourished in Europe in the later Eocene and Miocene periods, and of which three genera are known. Each of these was at first ascribed to a distinct family of the Hystricomorpha---namely, Theridomys to the Octodontidee, Archeeomys to the Chinchillida, and Issiodoromys to the Caviida. M. Gervais was the first to remove them entirely from that section, uniting the first two in his tribe Theridomins of the family My oxides (which also included Anomalurus). He placed Issiodoromys in his tribu des PMetins ot the Dipodida, but with the remark that it might have to be relegated to the Theridomins*. That these animals were strictly myo-morphine is clearly shown by the form of their mandibles. JNow that Anomalurus has been definitely separated from the Myoxida, there seems to be nothing to unite these ancient rodents with that Fig. 4. Mandible of Capromys pilorides. family ; and, both in their very varied dentition and in what we of their cranial characters, they appear to me to be very nearly related to the Dipodida-the two former to the true Dipodina, and the last to the Pedetina. Meantime it may be best to allow them to stand as a distinct family under the name of Theridomyidee. The last family of the Myomorpha, the Dipodida, is divisible into three plainly marked subfamilies-Jaculina, Dipodina, and * Zool. et Paleont. Franc, (2me ed.), pp. 31-36. |