260 A Subdivision of the Qeniis Uiomya. 



XXIX. — A Subdivlnon of the Genus Uromys. 

 By Oldfield Thomas. 



(Published by permission of the Trustees of the British Museum.) 



The genus Uromys, which ranges from the Mohiccas through 

 New Guinea and the Solomon Ishinds to North Australia, 

 has long been known to fall naturally into two very distinct 

 groups. These have been by myself spoken of as the large 

 species allied to U. macropus and the small ones allied to 

 U. bruijnii. Now, however, in connection with the working 

 out of some New Guinea mammals, I have had occasion to 

 examine them more closely, and find that the dift'erences 

 are such that those groups may very well be treated as genera. 

 In addition, the remarkable species U. sapienlis of the Solomon 

 Islands would seem also to deserve generic separation. 

 The three genera may be distinguished as follows : — 



A. Skull with projecting zygomatic plate. Bullaj 

 very small, little inflated. Mesopterygoid fossa 

 broad anteriorly, the palatal edge level with or 

 behind ?«'. 



a. Size large, hind foot 52 mm. and upwards, 



skull-length 60 mm. and upwards. Tail 

 long, commonly with contrasted white tip. 

 Palatine foramina very short, their length 

 not more than the distance from their hinder 

 end to ??i\ Back of palate behind level of 

 hinder edge of wi'. Incisors very deep in 

 proportion to their breadth, tlie depth of the 

 lower ones equalling the combined breadth 

 of the pair. Palate-ridges, where known, 

 consisting of a large number (12 or more) of 

 fine interdental ridges *, besides the usual 

 predental ridges I. Uromys, Peters. 



Synonym : Gymnomys, Gray. 



Genotypes of both names : IT. macropus t. Gray. 



Range : New Guinea, Aru Islands, and N. Queensland. 



Species described : anak, aniensis, viacro^ms, multipticatus, nero, 

 papuaniis, rothscJnldi, scapha.r, validus. 



b. Size smaller, the largest with hind foot 43 mm. 



and skull 51 mm., but the majority far 

 smaller. Tail usually shorter than in 

 Uromys, though occasionally long, either 

 wholly black, or lighter below, but not known 



* As tigured by Jeutink, ' Nuva Guinea,' v. pi. xvi. fig. (5. 



t Palmer erroneously gives celebensis as the genotype of Gymnomys ; 

 but a reference to P. Z. S. 1807, p. 5'J7, paragraph 5, will show that the 

 genotype is " Mus maeropus.' 



