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Show 1876.] MR. E. R. ALSTON ON THE ORDER GLIRES. 95 Fore limbs small; hind limbs elongate, with four or five toes. Fur soft. Tail moderate or long, bushy. Neotropical. Recent genera:- 1. Chinchilla, Bennett, Gardens &c. Zool. Soc. pt. i. p. 1 (1829). Ears broad, not elongated. Fore feet with five digits ; the pollex very small, but bearing a claw ; hind feet with four digits. Tail long, bushy. Skull with the auditory bullae enormous, appearing on the top of the skull between the supraoccipital, interparietal, and squamosals. Grinding-teeth rootless, with their enamel-folds nearly straight, each with three laminae; the two anterior laminae of the lower premolar imperfectly separated. 2. Lagidium, Meyer, Nov. Act. Acad. Nat.-Cur. xvi. p. 576 (1833). Ears elongated. Both fore and hind feet with four digits. Skull as in Chinchilla, but the auditory bullae more moderate, articulating on the top of the skull with the supraoccipital and squamosals only. Grinding-teeth similar, but their folds curved ; all three laminae of the lower premolar perfectly separated. 3. Lagostomus, Brooks, Tr. Linn. Soc. xvi. p. 102 . . . (1828). Ears moderate. Fore feet with four digits, and hind feet with three; the tarsus elongated. Tail moderate, bushy, tufted. Skull more massive than in the other genera, with well-marked sagittal and occipital crests ; auditory bullae smaller, not appearing on the top of the skull ; infraorbital opening with a separate canal for the nerve. Grinding-teeth with two laminae, except the last upper molar, which has three. Fossil genera:- 4. Amblyrhiza, Cope, Proc. Amer. Phil. Soc. xi. p. 183 . (1869). Grinding-teeth semirooted, each with either four or five laminae. 5. Loxomylus, Cope, op. cit. p. 187 (1869). Grinding-teeth as in Amblyrhiza, but each with three laminae only, their crowns obliquely sloped both longitudinally and laterally. Family IV. DASYPROCTID^E. Incisors long. Grinding-teeth semirooted, with external and internal enamel-folds. Milk-teeth long retained. Optic foramina separate ; palate broad; incisive foramina short; mandible with the masseteric ridge obsolete. Clavicles rudimentary. Form somewhat slender, limbs moderate ; upper lip entire ; ears short; tail short and naked or rudimentary. Fore feet with five digits; hind feet with five or three ; claws short and hoof-like. Neotropical. Recent genera :- 1. Dasyprocta, Illiger, Prod. Syst. Mamm. p. 93 . . . . (1811). Form compact; limbs long ; hind feet with three digits only ; tail either obsolete or short and subnaked. Skull elongate, smooth; infraorbital opening with no separate canal; malar simple ; parocci- |