134 COUES ON THE OSTEOLOGY 



Upon the opposite, i. e., the outer aspect of the head of the pedicellatum, is placed the 

 concavity for the reception of the head of the malar bone. It is on a lower level than the 

 pterygoid facet, and presents more directly forwards. It is a nearly circular and exceed- 

 ingly deep cavity. The small globular head of the malar is received into its concavity. 



The somewhat extensive surface resulting from the expanded head of the bone is wholly 

 occupied by the facet for the inferior maxillary. It is of an exceedingly irregular shape 

 and uneven surface ; in general terms, it may be said to be laterally much wider than long ; 

 to have a central depression bounded on each side and behind by elevations ; and to be 

 nearly divided into two lateral halves (corresponding to the lateral development of the 

 head to produce the pterygoid and malar articulations), by a notch which cuts deeply into 

 the posterior edge of the articulating surface To the inequalities of this surface, depres- 

 sions and elevations in the lower jaw are accurately coaptated. 



It is by this movable element of the temporal bone that the superior mandible receives 

 the slight motion which it is capable of. The movements of this bone are transmitted by 

 the malar to the superior maxillary, and by the pterygoid to the palatine, and thus the 

 upper jaw is elevated or depressed according as the pedicellate moves forwards or back- 

 wards. The extent of motion that the upper jaw is capable of, however, does not seem to 

 be as great as is the case with many other families. 



Pterygoid. These are two straight slender bones about three fourths of an inch long, 

 running obliquely inwards and forwards from the pterygoid facet on the inner edge of the 

 head of the pedicellatum, to the posterior extremity of the palatine, with both of which 

 they are movably articulated. Their shafts are slender, triangular on a transverse section, 

 marked on their superior faces with a longitudinal groove. Both extremities expand into 

 articulating facets. That of the posterior end is the largest ; and besides the oval concave 

 facet already noticed, by which it articulates with the pedicellatum, there is externally a 

 small irregular projection which abuts against the inner side of the root of the orbital pro- 

 cess of the tympanic bone. This seems to considerably restrict the extensive motion 

 which ordinarily results from a ball-and-socket joint, and to give it rather the character of 

 a free ginglymus. 



The pterygopalatine joint is a peculiar one. Two "claws," so to speak, project respec- 

 tively from the upper and under surface of the bone, and grasp between them a small pro- 

 jecting point of the extremity of the palatine. The resulting articulation is most admirably 

 adapted to its functions ; chiefly that of pushing the palatine bones directly forward, but 

 allowing also some inconsiderable lateral motion. 



Frontal. This bone forms the whole of the roof of the orbits, but only a comparatively 

 small part of the parietes of the cranial cavity proper. Its anterior border is quite straight, 

 forming the directly transverse fronto-maxillary " articulation." The lateral margins are at 

 first slightly bulging and convex, forming the anterior orbital processes; are then ascending 

 and deeply concave, forming the superior margin of the orbits ; and finally the bone 

 stretches far downwards and backwards, to form the pointed prominent overhanging poste- 

 rior orbital processes. Its posterior border is on the roof of the cranium anchylosed with 

 the parietal, so as to leave no trace of the original suture ; and in the back part of the 

 orbits is equally fused with the orbital processes and alae majores of the sphenoid. 



Its superior surface is at first thick and rapidly ascending, forming the prominence of 

 the forehead ; in the rest of its extent it is flat, and gradually rises as it runs backward. It 

 is marked in its whole length with a deep semdunar depression on each side, the con- 



