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Show 1876.] MR. E. K. ALSTON ON THE ORDER GLIRES. 80 foramina large. Incisors plain. Molars never tuberculate, the indenting folds deep and closed, those of the second and third lower molars sigmoid. 30. Neotoma, Say & Ord, Journ. Acad. Philad. iv. p. 346 (1825). Ears large, nearly naked; tail long, either sparsely haired or bushy. Upper incisors broad, plain. Molars never tuberculate, with open angular indenting folds, giving them a very arvicoline appearance. (ft. Molars semirooted or rootless.) I. A R V I C O L I N E . Molars composed of triangular prisms placed alternately. Skull with brain-case rhomboidal, frontals much contracted, infraorbital opening typical. Limbs moderate ; tail moderate or short, hairy. Palaearctic and Nearctic. Recent genera :- 31. Fiber, G. Cuvier, Legons d'Anatomie (1800). Form thickset; muzzle blunt; limbs short, subequal; hind feet fringed with long stiff hairs ; tail moderate, compressed, clad with scales and short hairs; supraorbital ridges united in a sagittal crest. Palate and lower surface of maxillaries minutely perforated. Incisors plain. Molars semirooted, separated into prisms, which are placed alternately. 32. Arvicola, Lacepede, Tableau (1803). Muzzle blunt; fore feet small, with short claws, soles naked; tail longer than the hind foot, clad with short hairs. Skull as in Fiber ; but the supraorbital ridges diverge after meeting, and converge again on the interparietal; palate not perforated. Incisors plain. Molars as in Fiber, rootless (rarely semirooted). 33. Myodes, Pallas, Zoogr. Rosso-Asiat. i. p. 173 . . . (1811). Muzzle blunt; fore feet moderate, with strong hooked claws ; soles hairy ; tail not longer than hind foot, hairy. Skull as in Arvicola, but the brain-case broader and the zygomatic arches stronger. Molars rootless, as in Arvicola, but the prisms of the posterior teeth usually compressed and twisted. K. SIPHNEINE. Molars as in the Arvicolina ; infraorbital opening small and subtriangular. Form cylindrical; ear-conch rudimentary ; limbs and tail very short. Palaearctic. Recent genera :- 34. Ellobius, Fischer, Zoognosia, iii. p. 72 (1814). Body subcylindrical; limbs very short, upper lip cleft; eyes small; no external ear-conch ; fore feet with short claws, but stronger than the hind feet; tail very short. Skull as in Arvicola, but the profile more arched and the facial portion shorter. Upper incisors arched forward. 35. Siphneus, Brants, Het Geslact der Muizen, p. 20 . . (1827). Eyes small; ears rudimentary ; fore feet with long, strong claws, |
