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Show 534 MR. G. A. BOULENGER ON THE [Dec. 4, Supraorbital edges evenly divergent, slightly beaded, but without any marked postorbital thickening. Outer plate of anterior zygoma-root short and weak, scarcely projected forwards. Anterior palatine foramina long, reaching backwards just to the level of the front of m.1 Bullae rather larger than in M. macleari, but far smaller than in M. everetti. Lower jaw very thin and slender, contrasting very markedly with M. macleari in this respect. Teeth 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 genus1. Its size, peculiarly small and delicate head, short 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 Musjavanus2, but its brown underside 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 locality3. Mr. Lister is to he congratulated on his discovery of this, the largest member of the indigenous Mammalian fauna of Christmas Island. It is unfortunate that he did not succeed in obtaining a female specimen of it, as its mammary formula, perhaps the most important character within the restricted genus Mus, therefore remains still unknown. 6. On the Reptiles of Christmas Island. By G. A. BOULENGER. [Eeceived October 15, 1888.] In addition to the three kinds of Reptiles4 found on the island by the ' Flying-Fish ' Expedition, examples of which were also obtained by Mr. Lister, we have to record two new Lizards, viz. a Gecko, and a Scink closely allied to the widely-distributed Ablepharus boutoni. Thus, of the five species of Reptiles now known to inhabit Christmas Island, four appear to be endemic, whilst the fifth, Gymnodactylus 1 Mus infraluteus, a species from Mount Kina Balu, North Borneo, described by the present author (Ann. & 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. 2 Obs. Zool. p. 63 (1804). 3 See supra, pp. 479-81. 4 Gymnodactylus marmoratus, Kuhl; Lygosoma nativitatis, Blgr. ; and Typhlops exocceii, Blgr. See P. Z. S. 1887, p. 516. |
