548 



REPTILIA. 



obliterated, so that the elements of this portion of their skeleton 

 remain permanently detached and separate ; and for this reason 

 we shall take the present opportunity of going a little into detail 

 concerning the composition of the skull of the Crocodile, as it is 

 well calculated to illustrate the real structure of the cranium in the 

 Vertebrata generally. 



The bones of the face are easily recognised ; the Intermaxillary 

 (fig. 246, 17), the Maxillary (18), and the Nasal (20), the Zy- 

 gomatic (b) and the Lacrymal (c), all occupy their usual relative 

 positions. The roof of the mouth is formed, as in Man, anteriorly 

 by a process of the upper jaw (Jig- 246, A, 18), and posteriorly 



by the palate-bone (22). 

 J Fig. 246. A 



The Frontal consists of five pieces ; viz. the Principal Frontal 

 (1), which probably in the fetus consisted of two lateral halves, 

 the Anterior Frontal (2, 2), and the Posterior Frontal (4, 4). 



The Parietal (7) is, as is generally the case in Reptiles, repre- 

 sented by a single bone. 



The Occipital consists of four pieces, which remain permanently 

 detached; namely, the Basilar (5), the two Lateral Occipital (10), 

 and the Superior Occipital placed above the foramen magnum. 



