Mammalia, 29 



coarse, but without the extremely long piles so characteristic of 

 M. macleari^ the longest hairs being about 40 or 45 mm. in length. 

 Hands and feet very thick and heavy; the claws, especially on 

 the fore feet, enormously broad and strong, not compressed, more 

 than twice the size of those of M. macleari, and evidently modified 

 for burrowing. Palms and soles naked, smooth; the pads broad, 

 low, and rounded, unusually little prominent; last hind foot pad 

 elongate. Tail shorter than the body without the head, veiy 

 thick, evenly tapeiing, nearly or quite naked ; its scales triangular, 

 very large, the rings averaging about seven or eight to the 

 centimetre ; ^ its colour uniform blackish brown throughout, above 

 and below, the white skin, however, showing to a certain extent 

 between the scales. 



"Skull" dis];)roportionally small, light, and delicate; compared 

 with that of M. maclcari it is slightly shorter and very considerably 

 narrower. Supraorbital edges evenly divergent, slightly beaded, 

 but without any marked postorbital thickening. Outer plate of 

 anterior zj-goma-root short and weak, scarcely projected forwards. 

 Anterior palatine foramina long, reaching backwards just to the 

 level of the front of m.2 EuUce rather larger than^n M. macleari, 

 but far smaller than in M. everetti. Lower jaw very thin and 

 slender, contrasting ver^' markedly with M. macleari in this respect. 



"'J'eeth- small and weak, their structure as usual. Front of 

 incisors orange above, yellow below. 



"This fine rat cannot possibly be confounded with any other 

 known species of the genus. ^ Its size, peculiarly small and deli- 

 cate head, shori unicolor tail, large hands and feet, and powerful 

 digging claws, separate it at once from any of its congeners. In 

 some respects it agrees with the description given long ago by 

 Hermann of his Mus javanus,^ but its brown under-side and naked 

 tail prove that it is not really the same, and it is probable that 

 Hermann's description was merely founded on an unusually large 

 specimen of Mus decumanus. 



" The presence of a second large rat in such a small island as 

 Christmas Island is a very noteworthy fact, and recalls the state 

 of things existing in Guadalcanar, Solomon Islands, where two 

 still larger rats, Mus imperator and M. rex, one terrestrial and 

 fossorial and the other arboreal, live side by side in the same 

 locality." ^ 



^ Ten to twelve in J/, macleari. 



- For figures of tlie skull and teeth see Plate II {bis), figs. 2, 4, 5, 9, 10. 



•^ Jlns infraluteus, a species from Mount Kina Balu, Xorth Borneo, described 

 by Mr. Thomas (Ann. and Mag. N. H. (6), ii, p. 409) since the above was 

 written, has a considerable superficial resemblance to M. nativitatis. Its tail, 

 however, is longer, and its skull is large and heavy, in due proportion to the size 

 of the body. 



* Obs. ZooL, p. 63 (1804). 



^ See supra, pp. 479-481. 



