OF COLYMBUS TORQUATDS. 137 



palatal process. From its inner border all around there arises a thin, delicate, concavo- 

 convex lamella of bone, projecting upwards, outwards, and backwards, its free rounded 

 margin inflected downwards so as to partially occlude a quite deep fossa, — probably the 

 analogue of our maxillary sinus, — antrum Highmorianum. While the bones forming this 

 sinus are tolerably broad, so as to divide the long palatine fissure into an anterior and pos- 

 terior part, they are so depressed vertically as scarcely to rise at all into the large nasal pas- 

 sages. But for the fact that it forms this quite conspicuous " antrum," the superior maxillary 

 would seem to constitute little more than an osseous band of connection between the four 

 bones already mentioned as anchylosing with it. The important part which it plays in 

 mammalia generally in the formation of the upper mandible is here quite usurped by the 

 intermaxillary. 



Malar or "zygomatic." Long and slender, measuring about two inches in length. They 

 form the lateral boundary of the inferior aspect of the skull. Arising from a perfect anchy- 

 losis with the superior maxillary, they at first curve a little outwards ; then more outwards, 

 with an inclination downwards; finally curving rather abruptly inwards and slightly 

 upwards to the outer edge of the head of the pedicellatum. They transmit the motion of 

 the latter directly to the superior maxillary, as the pterygoid do to the palatine. 



The malar bone, properly speaking, extends only three fourths of the distance to the 

 pedicellatum, the remaining being made up by the true zygomatic element of the tem- 

 poral. Traces of the fusion of the two are still clearly traceable in several oblique lines 

 and sulci. 



Palatine. The palate bones are long and slender, lying along each side of, and near to, 

 the median line of the skull. The width of their separation from each other forms the 

 palatal fissure. This amounts on an average to about a quarter of an inch ; but at their 

 posterior extremities the bones almost touch each other, being separated only by the width 

 of the thin sphenoidal spine. They begin very near the anterior extremity of the superior 

 maxillary bone, lying along its inner border, being more or less completely anchylosed 

 with it, and extending to within half an inch of its posterior termination. Thus far they are 

 simply plain, narrow, flattened spiculae of bone ; but shortly after leaving the maxillary 

 bones, they dilate laterally into very thin lamellae, their edges so much inflected downwards 

 as to give a transversely concave outline to their inferior surfaces. This dilatation ends 

 quite suddenly by a rounded free margin, which slopes inward and bends upward to form 

 the little projections which are grasped by the ends of the pterygoid bones. 



From the anterior portion of the superior aspect of these horizontal plates there rises 

 quite gradually a thin vertical lamella, which curls upon itself upwards and inwards towards 

 the median line, forming that part of the inner edge of the bones to which the vomer is 

 articulated. 



Vomer. The vomer, as usual, is situated directly in the median line, forming an incom- 

 plete septum between the right and left nasal passages. It is just one and a half inches in 

 length. Its inferior border, for one inch anteriorly, presents an exceedingly thin edge. For 

 the rest of its length it is bifurcate, — the right and left portions divaricating from each 

 other at a very acute angle, to articulate with the corresponding palatines. They are 

 probably, however, more or less completely anchylosed with the latter, so that little or no 

 motion is allowed. The superior surface of the bone is deeply grooved longitudinally for 

 nearly its whole extent ; the edge of the vertical lamella, the conjoined sphenoid and eth- 

 moid, being received into this groove, and riding freely through it during the movements 



