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Show 1888.] OF THE SOLOMON ISLANDS. 473 members of the genus, it agrees in the entire nakedness of the upper surface of its legs. From that animal, however, it is readily distinguishable by having a bright-coloured collar, by its hairier and less sharply pointed ears, and by its much more delicate teeth, the canine especially being far slenderer and lighter. PTERALOPEX, Thos. Pteralopex, Thos. Ann. Mag. N. H. (6) i. p. 155 (1888). External characters as in Pteropus. Ears short, hairy. Wings arising from the centre line of the back. Skull (Plate X X I . fig. 4) with a peculiarly short muzzle and flattened frontal region ; planes of the orbits much more nearly parallel to each other, and directed more upwards and less forwards, than in Pteropus. Orbits completed behind by bone (as previously recorded in Pteropus leucopterus alone of Chiroptera*). Sagittal crest more developed than in any Pteropus. Teeth (Plate X X I . figs. 5, 6) remarkable for their extraordinary cuspidate character. Upper incisors with broad posterior ledges. Upper canines (fig. 7) short vertically, enormously thick antero-posteriorly, each with one stout secondary cusp halfway up its posterior edge, and two smaller postero-internal basal cusps. Premolars and molars short and broad, their anterior and posterior basal ledges so developed and their main cusps so conical as to destroy all the appearance of longitudinal grooving characteristic of the genus Pteropus. Lower incisors extremely disproportionate in size, the outer not less than about twenty times the bulk of the inner. Canines very short vertically, with a simple posterior basal ledge. Cheek-teeth markedly cuspidate, the general longitudinal grooving quite obliterated. Posterior premolar and first molar each with three high anterior cusps, and a low posterior basal ledge, a form of tooth strikingly similar to that called " tuberculo-sectorial" by Prof. Cope, and found in the primitive members of several of the orders of Mammalia, and, notably, in the Insectivora. This remarkable genus is decidedly the most interesting of Mr. Woodford's Mammalian discoveries, both on account of its very striking dental characters, and especially for the fact that it seems to form an important link in the phylogeny of the Chiroptera. At first sight it might appear to be merely a highly specialized offshoot of Pteropus, but a careful comparison of the other members of the family has convinced me that this is not the case, and that it is more probably an isolated survivor from the time when the ancestors of the modern Pteropodidee still possessed cuspidate teeth-such teeth, which are still characteristic of nearly all the Microchiroptera, having been inherited from the Insectivora by the Palseochiroptera2, or common ancestors of all the living Bats. 1 Since the above was written, the British Museum has received, as a donation from the Genoa Museum, a specimen of Pt. nicobaricus, from Pulo Nias, with the orbits complete behind. Other specimens obtained at the same island, however, have their orbits incomplete, as usual, and the completed orbits of the first-named specimen are evidently due to its extreme age. 2 Cf. Dobson, Mon. Asiatic Chiropt. pp. 7 to 10, and diagram (1876). |
