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Show 96 MR. E. R. ALSTON ON THE ORDER GLIRES. [Jail. 18, pital processes short. Upper grinding-teeth with one internal and three or four external folds, the latter soon separated as isolated enamel-loops ; the lower teeth similar but reversed. 2. Ccelogenys, F. Cuvier, Ann. du Mus. x. p. 203 . . . (1807). Muzzle obtuse ; skin of cheeks reflected below the zygoma ; hind feet with five digits ; tail reduced to a tubercle. Skull with the zygoma enormously inflated, the anterior two thirds composed of the maxillary zygomatic process, which is hollowed out below into a great chamber, lined with mucous membrane and communicating with the mouth ; infraorbital opening with a canal for the nerve ; paroccipital processes long. Upper grinding-teeth with two internal and three external folds, except the third molar, which is reversed ; lower teeth with one external and three internal folds. Family V. DINOMYID^E. Incisors broad. Grinding-teeth rootless, with folds dividing them into transverse lobes. Optic foramina confluent. Paroccipital processes short. Palate broad. Clavicles imperfect. Manubrium broad. Upper lip cleft. Hair harsh. Tail rather long, bushy. Both fore and hind limbs with four digits; claws as in the last family. Neotropical. Recent genus :- 1. Dinomys, Peters, Monatsb. Ak. Berlin, 1873, p. 551 (1873). (Characters those of the family.) Family VI. CAVIID^E. Incisors short. Grinding-teeth with folds dividing them into transverse lobes. Milk-teeth shed during fcetal life. Optic foramina separate ; paroccipital processes long and curved ; palate contracted in front; mandible with a strong masseteric ridge. Clavicles imperfect. Upper lip entire; ears short or long; fur moderately soft; tail very short or absent. Fore feet with four digits, hind feet with three only ; claws as in last family. Neotropical. Recent genera :- 1. Cavia, Pallas, Misc. Zool. p. 30 (ex Klein, 1751) . . (1766). Body plump; limbs very short, subequal; ears short; hind feet not palmated ; no external tail. Skull much depressed ; malar slender ; palate much contracted in front, deeply emarginate behind, exposing the praesphenoid; incisive foramina long. Grinding-teeth each divided into two angular lobes. 2. Dolichotis, Desmarest, Mammalogie, p. 360 (1822). Limbs and ears long ; tail very short or rudimentary. Skull less depressed than in Cavia, and the facial portion comparatively larger ; palate still more deeply emarginate, exposing the vomer ; incisive foramina long. Grinding-teeth each divided into two angular lobes, except the third upper molar and the lower premolar, which have each three lobes. |
