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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![1. Lepus, Linnaeus, Syst. Nat. i. p.77 (1766). External characters those of the family ; all the grinding-teeth with three narrow laminae, except the last lower molar, which is small and simple. Fossil genus:— 2. Palceolagus, Leidy, Proc. Acad. Philad. 1856, p. 89 . (1856). Incisors longer than in Lepus, first lower premolar with only two laminae. Suborder III. Glires hebetidentati (subord. nov.). Incisors f; the second lower pair very small, and placed rather behind the middle pair, their enamel continuous round the tooth, and their crowns transversely hollowed, not chisel-edged. Grinding- teeth rootless, curved, with their convexity directed outwards. Mandibular condyles and glenoid cavity transverse. Fibula articu- lating with the calcaneum. One family:— Family I. Mesothertid^e. Two premolars above and one below; grinding-teeth rootless, with single reentering enamel-folds. Skull massive, with sagittal and occipital crests enormously developed, the latter running forwards at the sides to the zygoma; froutals with large postorbital processes; infraorbital opening small; malar very deep, running forward to the lachrymal; auditory bullae moderate; paroccipital processes long; bony palate perfect, produced behind the molars; mandible resembling in form that of Leporidce. Clavicles perfect; scapular and humerus resembling those of Castoridce. Both fore and hind limbs with five digits, claws probably short and hoof-like. Ischia articulated with two of the caudal vertebrae. Pliocene of South America. Fossil genus:— 1. Mesotherium, Series, Compt. Rend. Ac. Paris, xliv. p. 961 ' (1857). (Characters those of the family.) P.S. Since this paper was written I have been much pleased to find that the researches of my friend Mr. A. Doran, of the Royal College of Surgeons, into the form of the auditory ossicles of mam- mals, essentially confirm the views of affinity here adopted. Mr. Doran’s observations are yet unpublished; and it will be sufficient here to indicate their more general result. He finds in the auditory ossicles of the more typical Sciuromorpha a different type from that presented in the typical Myomorpha. Castor, though aberrant, approaches nearest to Arctomys; and Anomalurus is very close to Sciurus. Among the Myomorpha, Bathyergus has the characteristic type of the Hystricomorpha, in which, with few or no exceptions, the malleus and incus are ankylosed together ; and Dipus inclines in the same direction. The ossicles of the Glires duplicidentati pre- sent a distinct and less specialized type. [38]](https://iiif.wellcomecollection.org/image/b22455334_0042.jp2/full/800%2C/0/default.jpg)
