. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 860 PACHYDERMATA. support the unwieldy head or to tear up the ground in search of food, as the hog tribe do with their powerful snouts. In the young animal this bone always consists of four sepa- rate pieces—a basal, two lateral, and a superior occipital (fig. 471, c 1, r 2, c 3 :) but these soon become inseparably united into one mass. The frontal bones are of very great extent, and besides enclosing the anterior part of the cranial box, form a large proportion of the orbital cavity. In the young animal (Jig. 469,
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 860 PACHYDERMATA. support the unwieldy head or to tear up the ground in search of food, as the hog tribe do with their powerful snouts. In the young animal this bone always consists of four sepa- rate pieces—a basal, two lateral, and a superior occipital (fig. 471, c 1, r 2, c 3 :) but these soon become inseparably united into one mass. The frontal bones are of very great extent, and besides enclosing the anterior part of the cranial box, form a large proportion of the orbital cavity. In the young animal (Jig. 469, «, «) they are invariably two in number, separated by a suture along the mesial line, and in the American Tapir this separation is permanent; but generally they become con- solidated at an early age, leaving no trace of their original separation. The cctlnnoid is, in the Pachydermata, of very considerable size, proportioned to the acuteness of the sense of smell with which these animals are gifted. The cribriform plate holds a posi- tion exactly similar to that which it presents in the human subject, implanted between the frontal and sphenoid bones, and testifies, by its great extent of surface and the numerous foramina which pierce it, that the olfactory organs are highly developed. Towards the nasal surface, likewise, the cethmoidal cells and Fig. 468. Skull of Hippopotamus. Letters as in Fig. 465. Theparietalbones(figsA65,467,46Q,47l,f) are moderately extensive, covering the superior and lateral portions of the skull. In the young animal they are always separated by a mesial suture, CJ'g. 469,6, fr,) but in the adult are united by the obliteration of this suture into one piece, so as to appear but a single bone; a pro- vision, no doubt, for admitting the enormous force of the temporal muscles to be exerted without danger of divaricating the two lateral halves, which might otherwise be torn asunder at the line of junction. In the Tapir there is a lofty interparietal cre
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