SOLIPEDA. 



715 



OSTEOLOGY. Skull. The head of the horse 

 is at once recognisable by the following charac- 



ters*, namely, by the great enlargement be- 

 tween the orbits (Jig. 496. a), by its slightly 



Fig. 495. 



a, b, c, d, e, f, os frontis ; Z>, supra-orbital foramen ; h, i, k, parietal bone ; /, o, p, q, occipital bone ; 

 t, occipital protuberance ; p, condyle ; o, paramastoid process ; q, basilar portion ; r, s, t, u, w, x, temporal 

 bone ; r, zygomatic portion ; x, suture with the malar bone ; t, glenoid cavity ; , mastoid process ; ZP, 

 tympanic ring ; 1, 2, 3, 4, 5, 6, lacrymal bone ; 2, position of the nasal duct ; 7, 8, 10, malar bone ; 

 11, 11, 12, 13, 14, superior maxillary; 12, infra-orbital foi'amen; 15, intermaxillary; 16, nasal bone ; 

 17, 18, 19, 19, 20, inferior maxillary; 18, mental foramen; 19, 19, coronoid process; 20, condyle. 



Fig. 496, 



A, a, a, b, c, c, d, d, /, /, g, g, frontal bones ; A, 

 frontal suture ; h, h, i, ?', k, parietal bones ; m t n,n, 



occipital ; 0,0, o, p, q, r, temporal bones ; o, o, o, 

 zygomatic processes ; r, suture with the malar ; 

 s, s, t, u, u, nasal bones ; w, x, y, z, lacrymal bone ; * 

 1, 1, 2, 2, 3, 3, malar bones ; 4, 4, 5, 5, 6, superior 

 maxillary bones; 5, 5, infra-orbital foramina; 6, 

 palatal process ; 7, 8, 9, intermaxillary bones ; 8, 

 nasal process ; 7, palatal suture ; 9, foramen in the 

 suture ; 10, incisor teeth ; 16, 18, 18, inferior max- 

 illa ; 18, 18, summits of coronoid processes. 



convex profile, by the length of the face, which 

 is more than double that of the cranium, and by 

 the vertical depth of the lower jaw, which is 

 more than that of the whole cranial portion 

 of the skull. The temporal ridges, prolonged 

 backwards from the post orbital apophyses, ex- 

 tend as far as the middle of the parietal bones, 

 and there form a short sagittal crest upon the 

 mesial line of the skull, whence, proceeding 

 backwards, they diverge and extend as far as 

 the occipital ridge, which is truncated above 

 {as is the case in the pachyclermata generally), 

 and projects over the posterior surface of the 

 occiput. The intermaxillaries are prolonged 

 considerably beyond the nasal bones, which 

 last, by their points, arch over the cavity of 

 the nostrils to a considerable extent. The 

 temporal arch is comparatively very short, 

 nearly straight, and is situated entirely in the 

 posterior third of the skull. 



As regards the individual bones of the 

 skull, it may be observed that the twofronta/s 

 (fig. 496. a, a,f,g} remain distinct from each 

 other after the parietals become consolidated 

 into one piece; they are of remarkable breadth 

 between the orbits, and posteriorly penetrate 

 to a considerable depth between the parietal 

 bones. The ossa parictalia (fig. 495. /?, i) 

 give off on each side of the cranium a pointed 



* Cuvier, Ossemeus fossiles, t. ii. p. 108. 



