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Show 1 902. ] NEW BOLIVIAN RODENTS. 115 of the deep internal enamel infolding found in that genus. The premolar rounded,' triangular in section. Lower teeth oval in section, a slight median constriction on each side of m, and ma. This genus is, no doubt, closely allied to Octodon, of which it is a highland representative. NEOCTODON SIMONSI, sp. n. (Plates VIII. & IX. figs. 8-12.) General appearance very much as in the North-American Neotoma cinerea, strikingly different, by paler colour, whiter belly, and longer, more bushy tail, from either of the species of Octodon. Fur soft and fine, hairs of back about 22 m m . in length. General colour above pale drab-grey, grizzled with black. Sides clearer drab. Under surface snowy white, well defined laterally, where it extends rather high up; the bases of the hairs slaty except on the chin. Front of upper lip hairy, not grooved. Face coloured like the back, paler on the sides of the muzzle and cheeks ; no definite markings round eyes. A few longer vibrissa? placed just above eye, and a more prominent tuft of them between eye and ear. Ears large, shaped about as in Octodon, finely covered with short greyish hairs; a distinct tuft of white hairs at their anterior bases. Outer sides of arms and legs like back, inner sides like belly; upper surface of hands and feet pure white, the hairs stiff and elongated terminally, so as to surpass the claws; palms and soles entirely naked, strongly granulated, with projecting cushions, on which the pads are so small as to be scarcely perceptible among the granulations; under the heel the surface is comparatively smooth; pollex with a broad fiat nail; hallux short, with a claw, its tip falling some way short of the base of the second digit; fifth toe, without claw, reaching to the end of the basal phalanx of the fourth. Scrotum naked. Penis with a bone, which is flattened, tapering, though not to a point, about 15 m m . in length. Tail nearly as long as the head and body, thick, cylindrical, well clothed throughout with hairs, which increase in length to the end, where they may be fully an inch long. In colour the tail is brownish black above and at the end, white proximally on the sides and below; the hairs of the pencil-end are usually pale brown or even sandy brown, but this appears to be an effect of bleaching, more or less dependent on the season, as is the case in the British Squirrel. Skull and teeth as shown in the figures. Dimensions of the type, measured by Mr. Simons in the flesh :- Head and body 184 mm.; tail 152 ; hind foot, s. u, 36, c. u. 38 ; ear 32. gkull greatest length 46, basilar length 38, greatest breadth 24- nasals 17x5-8; interorbital breadth 10; length of frontal suture 13-5; breadth of brain-case 18-5; palate length 17'2; diastema 12; palatal foramina 4'8x2-4; length of upper tooth-series (crowns) 8#3 ; length of bulla 13; breadth of basi-occipital on suture 2-6. 8* |