732 



SOLIPEDA. 



which it is inserted, above the origin of the 

 stylo-hyoideus. 



The other muscles of this region exhibit 

 no peculiarities worthy of notice. 



The muscles of the tongue, of the palate, and 

 of Ike larynx, are in most quadrupeds strictly 

 comparable to those of the human species. 



Muscles of the Face. These, from the con- 

 formity of their general arrangement with 

 what exists in man, are distinguishable by the 

 same names as are employed in human an- 

 atomy. 



Fig. 504. 



Facial Muscles of the Horse. (After Sir CharlesBdl ) Jn ^^ 



contributes much to the expression of that 

 organ. 



The orbicularis palpebrarum (Jig. 504. a a) 

 arises, as in the human subject, from the com- 

 missural ligament at the inner canthus of the 

 eyelids, whence it winds round the orbit, its 

 lower fibres receiving attachment from the os 

 lachrymale. 



Internal to the last-named muscle are a few 

 fibres, that represent the corrugator supercilu. 



The Levator anguli oris (fig. 504. f, g) is, 

 likewise, extensively inserted into the upper 

 lip and margin of the nostril : it has two 

 origins, derived from the surface of the supe- 

 rior maxillary bone, between which the lateral 

 dilator of the nostril and upper lip passes to 

 its destination. 



The depressor of the lower eyelid (fig. 504. c) 

 is a short muscular slip, the use of which is 

 sufficiently indicated by its name. 



The zygomaticus (fig. 504. e] is a depressor 

 of the external angle of the eye, as well as an 

 elevator of the corner of the mouth, its fibres 

 being intermixed, with those of the orbicu- 

 laris palpebrarum, as well as of the orbicularis 

 oris. 



The long dilator of the nostril, and ele- 

 vator of the upper lip (fig. 504. z), arises at a 

 little distance below the inferior margin of 

 the orbit ; and, passing between the two ori- 

 gins of the levator anguli oris, terminates in 

 a tendon, which becomes connected with that 

 of the opposite side, and then spreads out in 

 front of the upper lip. 



From the tendon of the last muscle arises 

 the anterior dilator of the nostril (fig. 504 h ), 

 w r hich, acting upon the interior nasal carti- 

 lage, powerfully expands the aperture of the 

 nose. 



The other muscles viz. the orbicularis oris, 

 the levator labii superioris, the elevator of the 

 chin, and the depressors of the lower lip, and 

 angle of the mouth need no particular de- 

 scription. 



ALIMENTARY APPARATUS. Teeth. The 

 dental formula common to the Solipeda is as 

 follows : 



33 . l-l 



a, orbicularis palpebrarum ; b, d, cutaneous slips 

 which raise the outer and the inner commissures 

 of the eyelids ; c, depressor of the lower eyelid ; 

 e, zygomaticus ; f, g, levator anguli oris alseque 

 nasi ; h, elevator of the upper lip ; i, dilator na- 

 rium ; k, nasal cartilage ; I, m, orbicularis oris ; n, 

 masseter. 



The epicranius, or occipito-frontalis, exhibits 

 the usual origin from the posterior part of 

 the cranium, whence, running forwards, it 

 covers the skull with its tendinous aponeu- 

 rosis, and, in front, spreads in muscular slips 

 upon the forehead, some of which {fig. 504?. /) 

 extend downwards, to spread over those of 

 the orbicularis palpebrarum. 



Situated upon the outer side of the orbit 

 there is another descending slip of muscle 

 (j%504.cf)> apparently derived from the lateral 

 muscle of the cartilage of the ear which, by 

 elevating the external cnnthus of the eye, 



p, 



. 

 canine I~T premolars, 



33 



molars, 



33 



The canine teeth, 



3_3' ' ' 33 



however, it must be observed, only exist in 



the male sex. 



The incisor teeth, in the generality of her- 

 bivorous quadrupeds, are bevelled off poste- 

 riorly, so as to present in front chisel-like 

 cutting edges ; but in the Solipeds, when 

 young, the lateral incisors are furnished with 

 two cutting edges, one in front arid the other 

 behind, from which circumstance those cen- 

 tral fossae are produced which, as we shall 

 see further on, furnish important testimony 

 relative to the age of the animal. 



The canine teeth, here called "tusks," or 

 " tushes" are always of very moderate dimen- 

 sions, and their points, at an early age, become 

 flattened and blunt. Those of the upper jaw 

 are separated from the incisors by a con- 



