On the classification of the order Glires / by Edward R. Alston.
- Edward Richard Alston
- Date:
- 1876
Licence: Public Domain Mark
Credit: On the classification of the order Glires / by Edward R. Alston. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![that of the fifth digit being longer than the toe itself; tail short, hairy. Skull broader and more truncated behind than in Ellobius ; supraorbital ridges nearly parallel ; occipital crest sharp; infraorbital foramen subtriaugular. Upper incisors perpendicular. Fossil genera. The following genera will probably prove to be referable to this family:—Cricetodon, Lartet, Notice, p. 20 (1851) ; Eumys, Leidy, Proc. Ac. Philad. 1856, p. 90; Heliscomys, Cope, New Vert. Colorado, p. 3 (1873), Miocene of North America; My sops, Leidy, U.S. Geol. Surv. Terr. i. p. Ill (1873), Eocene of America. Family IV. Spalacidje. Incisors large; premolars present or absent; grinding-teeth rooted, not tuberculate, with reentering enamel-folds. Infraorbital opening moderate or small, with no perpendicular plate ; occipital plane high, often sloped boldly forward ; palate narrow. Form cylin- drical ; eye and ear-conch very small, sometimes rudimentary ; limbs short and stout; claws large; tail short or absent. Two sub- families :— A. Spalacin^e. Palate between the molars broader than one of the alveoli. No interpterygoid fissure. Mandible of normal myo- morphine form (the angular portion springing from the edge of the bony covering of the lower incisors). Palsearctic, Indian and Ethi- opian. Recent genera:— 1. Spalax, Giildenstadt, Nov. Comment. Petrop. xiv. i. p. 409 (1770). Head broad, flat, with a ridge of long stiff hairs on each side; eyes rudimentary, covered by the skin; no ear-conch or external tail; feet broad, claws short. Skull depressed, occipital plane high and sloped boldly forward ; parietals and interparietal small and soon ankylosed ; infraorbital opening moderate, suboval. Upper incisors plain, nearly perpendicular. No premolars. Molars with curved ena- mel-folds in youth only. 2. Rhizomys, Gray, P. Z. S. 1830, p. 95 (1830). Form robust; eyes very small; ears very short, naked; pollex rudimentary ; tail rather short, partially haired. Skull broad, occi- pital plane only slightly sloped forward ; infraorbital opening small, subtriangular. Upper incisors arched forward. No premolar. Upper molars with one deep internal and two or more external enamel-folds ; the lower molars reversed. 3. lleterocephalus, Riippell, Mus. Senkenb. i. Saugeth. p. 99 (1834). Eyes very small; no ear-conch ; pollex short, not rudimentary ; tail short; whole body almost hairless. Skull as in Rhizomys, but broader, occipital plane more perpendicular, and infraorbital fora- men larger. Dentition similar, but the upper molars with an exter- nal indenting fold only, the lower with one external and one internal fold. [26]](https://iiif.wellcomecollection.org/image/b22455334_0030.jp2/full/800%2C/0/default.jpg)
