3° ANATOMY OF A CHELONIAN. 



palate bone and the vomer, and, lying on these, 

 the naso-ethmoid cartilaginous rod (28). 

 m. In front of the naso-prefrontal bone is seen the 

 nostril cavity, bounded below by the maxilla 

 and the premaxilla ; externally by the maxilla 

 and the naso-prefrontal bone ; and above, by 

 the latter bone. 



57. The Hyoidean Apparatus is largely cartilaginous, 

 except in old specimens. It presents — 



a. A median piece, or body, with a concavity on 

 its dorsal side into which the larynx and the 

 anterior end of the trachea fit. The ventral 

 surface of the body of the hyoid is convex, 

 and its most prominent median part is com- 

 posed of a connective-tissue membrane. From 

 its anterior end arises a small median pointed 

 process, which, in the recent state, enters the 

 tongue. To each antero-lateral angle a small 

 cartilaginous nodule is attached by a fibrous 

 membrane. 



b. Attached to the sides of the body of the hyoid, 

 about half way between its anterior and pos- 

 terior ends, are the curved anterior cornua, 

 which ossify earlier than the rest of the hyoid- 

 ean apparatus. They run back, in their nor- 

 mal position, parallel with and close to the 

 posterior border of the mandible. 



c. The postero-lateral angles of the body of the 

 hyoid form diverging processes to which the 

 posterior cornua are attached ; they are shorter 



and stouter than the anterior cornua, and are 

 curved in the opposite direction. 



