304 PEOF. T. W. BRIDGE ON THE [-A-pr. ^ 



As far as could be seen in the dried skull, the usual connection 

 between the anterior extremity of the palato-pterygoid bar and 

 the lateral ethmoid of its side must have been of a loose 

 ligamentous character. Between the metapterygoid and the 

 parasphenoid there is a singular articular connection. From the 

 antero-superior angle of the metapterygoid a process (fig. 3, mt.a.) 

 is bent inwards towards the base of the skull and lies in the 

 horizontal plane. The anterior and posterior margins of the 

 process are cm-ved shghtly upwards in such a way that the process 

 forms a somewhat shallow, demi-cylindrical, articular surface, the 

 concavity of which looks directly upwards. The mesopterygoid 

 (figs. 3 and 4, mp.g.^), which, as already mentioned, overlaps the 

 inner surface of the metapterygoid, is also bent horizontally 

 inwards, but at its postero-superior angle, and, moreover, partially 

 embraces the preceding process in such a way as to strengthen the 

 floor and, at the same time, deepen the sides of the demi-cylinder. 

 The hyomandibular also contributes to the formation of this 

 curious articular surface. A process ^ from the anterior margin of 

 the superior half of that bone (fig. 3, Jiym}) is prolonged obliquely 

 downwards and forwards, and, after blending with the anterior lip 

 of the demi-cylinder, becomes applied to the adjacent upper 

 margin of the mesopterygoid (m.pg.). It will be seen, therefore, 

 that this process not only strengthens the anterior wall of the 

 demi-cylinder, but, in addition, furnishes the latter with an 

 incomplete roof. In the normal condition of these parts the 

 articular processes of the parasphenoid fit into the two demi- 

 cylindrical articular surfaces provided for them by the meta- 

 pterygoids, in such a way, that a lateral sUding motion of the latter 

 on the parasphenoid is possible. 



In addition to the acutely-pointed teeth in the premaxillae, 

 maxillsB, and vomers, both the mesopterygoid and pterygoid bones 

 carry teeth of variable size over nearly the whole extent of their 

 inner or oral sm-faces. The inferior border of the pterygoid 

 (fig. 3, pg.) carries a series of small pointed teeth arranged parallel 

 to the more externally situated and larger maxillary teeth (mx.). 

 The rest of the inner surface of the bone (fig. 4, ^j^.) exhibits a 

 granular appearance, from the presence of numerous, extremely 

 fine, closely-set teeth. For the same reason the greater part of 

 the oral surface of the mesopterygoid (m.pg.') has a very similar 

 appearance, but, within a short distance of the superior margin of 

 the bone, the fine denticles are replaced by a single longitudinally 

 disposed row of much larger, conical, pointed teeth (fig. 4). Of 

 these teeth the most posterior are the largest, and, moreover, are 

 situated exactly opposite the mesial cluster of teeth in the 

 parasphenoid ; from this point forwards the teeth gradually but 

 rapidly diminish in size. The teeth are slightly curved, and hence 

 their pointed enamel-tipped crowns are directed obUquely inw'ards 

 and a little downwards towards the corresponding teeth of the 



^ I am inclined to think that this process is not an actual extension of the 

 hyomandibular, but, on the contrary, is really an ossified ligament. 



