EQUID^E 



389 



chiefly in consequence of the immense size of the face as compared 

 with the hinder or true cranial portion. The basal line of the 

 cranium from the lower border of the foramen magnum to the 

 incisor border of the palate is very nearly straight. The orbit, of 

 nearly circular form, though small in proportion to the size of the 

 whole skull, is distinctly marked, being completely surrounded by a 

 strong ring of bone with prominent edges. Behind it, and freely 

 communicating with it beneath the osseous bridge (the postorbital 





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Fio. 103. Side view of skull of Horse, with the bone removed so as to expose the whole of 

 the teeth. PMx, Premaxilla ; MX, maxilla ; Na, nasal ; Ma, malar or jtigal ; L, lachrymal ; F r, 

 frontal ; Sq, squamosal ; Pa, parietal ; oc, occipital condyle ; pp, paroccipital process ; t 1 , i 2 , 

 and i 3 , the three incisors ; c, the canine ; pm 1 , the situation of the rudimentary first premolar, 

 which has been lost in the lower, but is present in the upper jaw ; pm-, pm 3 , and pm*, the 

 three fully developed premolars ; m 1 , ?n 2 , and m 3 , the three true molars. 



process of the frontal) forming the boundary between them, is the 

 small temporal fossa occupying the whole of the side of the cranium 

 proper, and in front is the great flattened expanse of the " cheek," 

 formed chiefly by the maxilla, giving support to the long row of 

 cheek-teeth, and having a prominent ridge running forward from 

 below the orbit for the attachment of the masseter muscle. The 

 lachrymal occupies a considerable space on the flat surface of the 

 cheek in front of the orbit, and below it the jugal or malar does 

 the same. The latter sends a horizontal or slightly ascending 

 process backwards below the orbit to join the under surface of the 

 zygomatic process of the squamosal, which is remarkably large, and, 

 instead of ending as usual behind the orbit, runs forwards to join 

 the greatly developed postorbital process of the frontal, and even 



