The Skeleton 63 



quadrate articulates with the quadratojugal ; me- 

 dially with the basisphenoid and exoccipital; dor- 

 sally with the exoccipital, squamosal, postfrontal, 

 and, possibly, with the pro-otic; ventrally with the 

 pterygoid, alisphenoid, and probably with some of 

 the otic bones. Its dorsal side forms most of the 

 floor of the external auditory meatus which will be 

 described later. While the basioccipital may be 

 seen from the dorsal side, it is not really one of the 

 dorsal bones of the skull and will be described later ; 

 the same is true of the pterygoids and palatines 

 which may be seen through the empty orbits. 



The Ventral Aspect (Fig. 20). The larger part 

 of this side of the skull is made up of four pairs of 

 bones: the premaxillas, the maxillae, the palatines, 

 and the pterygoids, lying, from anterior to posterior, 

 in the order named. 



The premaxilla (i), as described in the dorsal 

 view of the skull, is a triangular bone which, with 

 its fellow, forms the anterior end of the snout. 

 Each premaxilla bears five teeth, not only in the 

 alligator but in the crocodile, the caiman, and in the 

 gavial. Of these teeth the fourth from the front 

 is the largest; the first two are small, and the 

 third and fifth are of intermediate size. This 

 arrangement as to size is also true, apparently, in 

 the other groups of Crocodilia. The ventral surface 

 of the premaxilla, which is more or less flat and 

 horizontal, is pierced by a number of small fora- 

 mina, in a row parallel to the curved outer margin 



