Guide to the galleries of mammalia (mammalian, osteological, cetacean) in the Department of Zoology of the British Museum (Natural History).
- British Museum (Natural History). Department of Zoology.
- Date:
- 1892
Licence: Public Domain Mark
Credit: Guide to the galleries of mammalia (mammalian, osteological, cetacean) in the Department of Zoology of the British Museum (Natural History). Source: Wellcome Collection.
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![mammals, there being only a single toe on eaeh foot (fig. 49); but in their ancestors, as shown in the Geological Guide, p. 23, the toes are present in greater numbers as we go back in time. Their molar teeth are large, quadrangular, and highly complex, the enamel-foldings being extremely numerous when compared with the simpler ones of the Rhinoceros and Tapir. In their skulls and teeth all the recent Horses and Asses show scarcely any dif- ference, the species being merely separated by size, form of tail, colour, and other external characters. Suborder Artiodactyla. The Artiodactyla, or Even-toed Ungulates, are so called because their feet always possess an even number of toes, two or four, the centre line of the foot passing down between the toes which correspond to the third and fourth of the complete or typical five- toed mammaks foot; these two toes are always equal, and larger than the second and fifth, if these are present; the first, corre- sponding to our thumb, is (as in existing Ungulates generally) always absent. The metacarpal and metatarsal bones of the third and fourth digits are generally united, and form what is known as the cannon bone.^^ The premolars and molars are quite distinct in shape, the former being single- and the latter two-lobed. The dorsal and lumbar vertebrse together invariably number nineteen. The Artiodactyles may be, as already noticed, p. 38, divided into two groups. Non-ruminants and Ruminants—groups charac- terized also by their dentition, the teeth of the former being covered with blunt, rounded cusps, and those of the second having two pairs of crescentic ridges on their surfaces. The non-ruminating Artiodactyles are Hippopotami and Pigs. [Qase 13 ] The former (Case 13) possess broad skulls, huge lower jaws, and great canine teeth, which, if the corresponding tooth in the opposite jaw is lost, will continue to grow, forming great outwardly curved tusks, such as the one placed in Div. B. The molars are large, square, and complex. The dental formula of the common Hippo- potamus, of which a skeleton stands in the centre of the Gallery, is I. §, C. Pm. M. § X 2 = 40; the skull of a fine skeleton of the diminutive Liberian Hippopotamus exhibited in this case shows only one lower incisor on the left side, but two on the right.](https://iiif.wellcomecollection.org/image/b28122574_0103.jp2/full/800%2C/0/default.jpg)
