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Show 1896.] GENERA OF RODENTS. 1013 N o w , every Museum-curator when arranging his specimens, and every writer either of a text-book or of a faunistic work, is constantly being confronted by the difficulty as to where to place in the system this or that genus of Rodents, for which he has perhaps himself neither time, inclination, or opportunity to search out a proper and appropriate position. It is for the object of helping such persons that the present paper has been prepared, so bold a venture being due to the fact that the increase in the British Museum collections has fully kept pace with the general increase of knowledge, and that there are very few genera known from any part of the world of which specimens are not in that collection1. With such unrivalled material available, the opportunities for mistaken work have been reduced to a minimum; and in the following list it may be said that the specimens have been allowed to sort themselves, and where m y alterations are found to be strikingly different from those of Alston it will generally be found that the forms referred to were not available for examination in his time 2. One recent author only has diverged much from Alston's system, namely Dr. Winge of Copenhagen, who, in connection with his work 3 on the Rodents of Lagoa Santa in Brazil, has written a revised general arrangement of the Rodents. His classification, however, is a rather one-sided one, being based almost entirely on the structure of the masseter muscles and the bones related to them, and, however thoughtful and clever it may be in many ways, is so widely divergent from all previous classifications that without much stronger reasons than he adduces I should not be prepared to follow it. N o doubt many of his alterations are admirable, such, for example, as the reference of Sminthus to the Dipodidae; but when w e find Pedetes placed with Anomalurus, and Platacanthomys combined with Myoxus in a group set over against Graphlurus, we see that a good deal of confirmation will be needed before the classification the world is accustomed to is abandoned in favour of that proposed by Dr. Winge. Prof. Zittel4 and Dr. Tullberg 3 have also contributed to tbe revision of the classification of tbe Rodents. The former gets rid of the difficulties by putting all the awkward families into a separate group, the Protrogomorpha. The latter largely follows Winge, but does not as yet enter into details. Dr. Trouessart's most useful list of Rodents is entirely based on Alston's arrangement, and is so admittedly a compilation that no special criticism of it is here necessary. N o attempt has been made to follow Alston's example of giving diagnoses of the groups and genera, partly for the simple reason 1 Of the 159 genera now admitted, only the following 15 are not represented in tbe Museum collection: Idiurus, Oreinomys, JDeomys, Limacomys, Pitheco-chirus, Hallomys, Hypoyeoniys, Nothings, Xenomys, Microdipodops, Euchoreutes, Massouliera, Cercomys, Dinomys, and Romerolagus. 2 E. g., Heterocephalus, Lophuromys, Steatomys, Saccostomus, &c. 3 Jordfundne og nulevende Gnavere fra Lagoa Santa, E Mus. Lundii, iii. 1887. * Handb. Palasontol. p. 512 (1893). 5 Muriden aus Kamerun (Nova Acta Soc. Upsala), sec. 3, xvi. p. 4 (1893), |
