ANATOMY ()F THE HORSE. 33 



The orbital surface is triangular and smooth, deeply excavated 

 in front, extended and flattened posteriorly, and makes the antero- 

 external side of the orbit. In the excavated part are observable — a 

 circular depression, marking the origin of the short oblique muscle 

 of the eye, and, before the depression, the lachrymal fossa, a funnel- 

 shaped hollow, forming the entrance into the lachrymal canal : 

 within the hollow reposes the lachrymal sac; the canal is traversed 

 by the lachrymal duct. 



Borders. — Denticulated, with the exception of the nasal, 

 which is plain. The external facial border articulates with the 

 malar bone ; the intenialfacial (including the nasal border), with 

 the nasal and frontal bones : the external orbital border unites 

 with the malar and maxillary bones ; the internal orbital border 

 with the frontal bone. 



Particularities. — A semi-transparent bone, important from its 

 connexion with the lachrymal apparatus. 



Connexion.— Vf'Ah the frontal, nasal, malar, and superior 

 maxillary bones. 



PALATE BONES. (OSSA PALATI.) 



Situation. — Infero-posterior part of the face, adjoining the 

 base of the cranium. 



Figure. — One portion is semi-circular; otherwise it is irregular. 



Surfaces. — The palatine surface is that which is turned 

 downwards, and contributes to the formation of the palatine arch. 

 The nasal surface, the broadest, confronts its fellow, the two 

 forming the sides of the posterior opening of the nose : its supero- 

 posterior part is pierced by the posterior palatine foramen. The 

 orbital surface is in part smooth, where it enters into the compo- 

 sition of the back of the orbit; and in part rough and laminated, 

 where it articulates with the superior maxillary bone : the latter 

 portion exhibits the palatine canal, which leads to the anterior pala- 

 tine foramen. Between this and the superior maxillary bone, a 

 hiatus or sort of vestibule is left vacant, in which is observable the 

 posterior opening of the foramen above-mentioned, besides two 

 others formally described. The ethmoidal surface is divided from 

 the nasal by the palatine crest, to which the vomer is joined : it is 

 oblong and concave, and constitutes the floor of the ethmoidal 

 sinus, possessing several irregular ridges, which form so many im- 

 perfect septa, projecting into the cavity. 



Borders. — The palatine, round, smooth and lunated, forms 

 the circumferent boundary-line of the posterior opening of the 

 nose, and afibrds attachment to the velum palati : from it, poste- 



