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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![noted that they have no true alisphenoid canal, but a carotid canal is present in the tympanic*. The optic foramina are confluent; and the bony palate is reduced to a mere bridge between the molar series, being bounded in front by the large confluent incisive foramina, and behind by the deep posterior emargination. The fibula is ankylosed below with the tibia, and articulates with the calcaneum. There are no vesicular glands; and the testes are permanently external. The two families Leporidce and Lagomyidce are certainly very nearly allied, but differ in several important characters; and I have therefore followed Professor Lilljeborg in keeping them distinct. The absence of postorbital frontal processes, the posterior continua- tion of the zygoma towards the auditory meatus, the absence of reticulation in the facial portion of the maxillary, and the full development of the clavicles in the Pikas are among the points in which their anatomy confirms their distinction from the Hares, out- wardly indicated by the different proportion of their ears and tails. The remark has been madeabove that palaeontology has hitherto not yielded much of interest to the student of this order. A striking ex- ception, however, is to be found in certain wonderful forms from the South-American Miocene and Pliocene, of which the true position has been much disputed. Of these the most striking is the huge animal whose skull, discovered by Mr. Darwin, was described by Professor Owen under the name of Toxodonf, and since more fully investigated by Dr. BurmeisterJ. Its Ungulate characters, however, much over- weigh in importance those which it has in common with the Rodents; and it may therefore he dismissed from present consideration. Another animal presenting an extraordinary combination of cha- racters is that discovered by M. Bravard, and placed by him, under the name of Typotherium, among the Pachydermata§. Almost every part of its skeleton has been obtained; and the w hole has been well described by M. Serres|| under the name of Mesotherium, and by Professor Gervaislf under Bravard’s name**. The last-named zoolo- gist considers that it must be regarded as a link between the Rodents and the Perissodaetyles, and that its nearest affinities are with the Leporidce. The most important characters in which Mesotherium differs from existing Rodents are, briefly, the transversely hollowed crowns of the incisors (which have not the chisel-edge so characteristic of * Cf. Turner, P. Z. S. 1848, p. 65. t Zoology of the ‘ Beagle,’ pt. 1, pp. 16-35. t Ann. Mus. Pub. de Buenos Aires, i. pp. 254-286. § Catalogue des especes d’anim. foss. recueillis dans l’Amdr. du Sud, 4to. Parana, 1860. I| Comp. Bend. Ac. Paris, xliv. p. 961 (1857); lxv. pp. 6, 17, 140-148, 273-279, 429-437, 593-599, 740-748, 841-848. IF Zool. et Paleont. Generates, pp. 134-137, pis. xxii.-xxv. ** M. Gervais regards Bravard’s name as having priority ; on what grounds I cannot discover. It does not appear whether or not it was used in the latter writer’s paper on the Geology of La Plata, published in the ‘ Begistro Esta- distico’ of Buenos Ayres in 1857 (which M. Gervais was unable to find in Paris, and which is not in the British Museum); but even if it was it would only be contemporary with M. Serres’s very appropriate name. [13]](https://iiif.wellcomecollection.org/image/b22455334_0017.jp2/full/800%2C/0/default.jpg)
