Recent polydactyle horses / by O.C. Marsh.

  • Marsh, Othniel Charles, 1831-1899.
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: Recent polydactyle horses / by O.C. Marsh. 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.

    14/18 (page 352)
    852 at first supposed to have close affinities with suilline mammals. Some of the latter ma.y, in fact, be included in the species referred to these genera. Yarious perissodactyle forms, also from the Eocene of this country, have since been described by Cope under the generic name FhenacoduH (1873), which is clearly identical with Helohyus, and some of these have been referred, under the former name, to the equine ancestral line.* These mammals have been placed by the writer in a distinct family, the IIelohyidce,.\ Helohyidce. The IIelohyid(E may with some probability be now regarded as the family from which equine mammals were derived. The members of this group were small perissodactyle mammals, with forty-four teeth without cement, the premolars unlike the molars, and both with short bunodout crowns. The ulna and fibula were complete and separate, and the feet had four or five functional digits. All the known forms are from the Eocene, During Tertiary time, this family apparently separated into various branches, some of which became specialized, and died out, while smaller forms became modified into the lines by which the horse, the tapir, and the rhinoceros gradually developed. Orohippidoe,. The successors along the first line form a well-marked family, which the writer has called the Orohip])id(E.X The represen- tatives of this group were small equine mammals having forty- four teeth without cement, incisors without pit, canine teeth large, and the molar series with short crowns, and the cusps more or less flattened. The ulna and fibula were complete, and there were three or four functional digits in each foot. The members of this family appear to be all from the Eocene or Miocene. EquidcB. Next in the succession came the Equidm, of which the horse is a typical member. All are large equine mammals, with less than'forty-four functional teeth with cement, incisors with pit, canines small or wanting, the molars elongated, and the pre- molars essentially like the molars. The ulna and fibula are incomplete, and there is but one functional toe on each foot. These mammals lived in Pliocene time, continued on to the pres- ent, and are now represented by the horse, ass, zebra, and quagga. *W. 11. Flower. The Horse, London, 1891; also, Madame Pavlow, L'Histoire Pal. des Ongules, I-V, Moscou. 1887-1890. f This Journal, vol. xiv, p. H64, November, 1877. X Ibid., vol. vii, p. 249, 1874.