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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![G8 drical, either covered with scales arranged in rings, or more or less hairy. The Myomorpha contains such a variety of forms, many of them much specialized, that it is only by allowing for exceptions that its definition can be carried further ; still many and important distinctions are common to the vast majority. The form of the man- dible, by which the section was first separated from the Hystrico- morpha, agrees with the last section, the angular portion springing from the lower edge of the bony covering of the lower incisor, excepting in the subfamily Bathyergince, in which it has exactly the form so characteristic of the hystricine rodents. The other cranial characters are very varied. In the more typical forms the infra- orbital opening has a peculiar shape, which may be termed murine ; it is high, perpendicular, narrow, wider above than below ; and the lower root of the maxillary zygomatic process is perpendicular and flattened into a thin plate with a rounded anterior edge. The zygoma is comparatively slender; the malar seldom advances far forward (except in the Dipodidce), and is usually supported below by a con- tinuation backwards of the maxillary process, being reduced in some Fig. 3. Mandible of Bathyergus maritimus. of the typical genera to a mere splint between the latter and the squamosal process. The outer walls of the pterygoid fossae are gene- rally obsolete; and they have no direct fissure at the bottom, except in the aberrant subfamily named above. The clavicles are perfect except in the Lophiomyidcn. [8]](https://iiif.wellcomecollection.org/image/b22455334_0012.jp2/full/800%2C/0/default.jpg)
