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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![The difference between the mandible characteristic of the Sciuro- morpka and Myomorpha and that peculiar to the Hystricomorpha will be best shown by a comparison of the figures*. In the more typical forms the infraorbital opening is not enlarged to give passage to a portion of the masseter muscle ; and in all the malar extends far forward, and is not supported below by a continuation backwards of the maxillary zygomatic process. The incisive foramina are small, and confined to the intermaxillaries ; the foramina of the base of the skull are proportionally small; and there is no interpterygoid canalf. The clavicles are always perfect, the posterior ridge of the scapula is strongly developed, and the acromion is broad and flattened. Externally the muffle is naked, the upper lip usually cleft, the nostrils rounded above and comma-shaped, the ears hairy, and the tail cylindrical and well haired, except in Castor, in which it is flattened and scaly. The typical family, the Sciurida, easily distinguished by their postorbital frontal processes, has been divided for convenience into two subfamilies, the long-tailed arboreal Squirrels (Sciurince), and the short-tailed terrestrial Marmots (Arctomyiiue), though it must be confessed that their differences are merely adaptive and not very striking. The other families are all more or less aberrant, and their true affinities have been the subject of much discussion. The first of these is the Anomaluridce; and I have already! given my reasons for considering that it must be regarded as an undoubted though specially differentiated family of this section. The sciurine affinities of the Haplodontidat, in spite of its peculiar dental and cranial characters, have been definitely established by Dr. Peters§, although Prof. Lilljeborg has strangely relegated it to the Hys- tricomorpha(j. The position of the remaining family, Castorida;, has been a still more vexed question, ever since the Beaver has been extricated from the old jumble with the Musquash and the Coypu. Professor Gervais appears to have been the first to treat Castor as an aberrant member of the present group ^f, in which Mr. Water house** and Professor Bairdj~f have concurred ; and although these writers have not been generally followed, it seems evident to me that we must revert to their views. Professor Brandt fully recognized that in all the more important points the osteology of Castor agrees with that of the Sciuromorpha, but considers this resemblance to be negatived by the external habitus and manner of life, as well as by the structure of the teeth, feet, and tail!!- Prof. Lilljeborg places the * By permission of Professor Flower the illustrations have been drawn from specimens in the Museum of the Royal College of Surgeons. t This name was proposed by Mr. Waterhouse for the fissure which in some rodents leads from the bottom of the pterygoid fossa into the orbit. Cf Turner, P. Z. S. 1848, p. 63. X “ On Anomalurus, its Structure and Position,” P. Z. S. 1875, pp. 88-97. § Monatgb. Ak, Berlin, 1864, p. 177- || Op. cit. p. 9. Diet. XJniv. d’Hist. Nat. xi. p. 203. ** Physical Atlas, Zool. map, 5 (letter-press). ft North-American Mammals, p. 350. t+ Op. cit. pp. 149, 150. [6]](https://iiif.wellcomecollection.org/image/b22455334_0010.jp2/full/800%2C/0/default.jpg)
