V THE SKULL OF REPTILES 83 



the extent of the elevated facial carina in front of the nares, and the 

 shape of the teeth, more slender and cylindrical in those with slender 

 jaws, more flattened and compressed in those with a compressed and 

 elevated face, doubtless because of the more dominant fish-eating 

 habits of the former, the more general carnivorous habits of the 

 latter. 



The Skull of the Crocodilia 



(Figs. 68, 69) 



The skull of the Crocodilia invariably lacks the postfrontals, 

 supratemporals, epipterygoids, tabulars, septomaxillae, and parietal 

 foramen, and the paroccipital is fused with the exoccipital. The 

 parietals and f rentals are fused in the midline. The supraoccipital 

 is a triangular bone, excluded from the foramen magnum. The 

 quadratojugals take part in the formation of the lateral temporal 

 opening, narrow bones between the quadrates and jugals extending 

 forward to meet the postorbitals. The quadrates are firmly wedged 

 in between the quadratojugals, postorbitals, parietals, exoparoccipi- 

 tals, postoptics, squamosals, prootics, basisphenoid, and pterygoids, 

 an extensive connection. The supratemporal openings are large in 

 the early forms, small in the later ones, and almost [or entirely] obso- 

 lete in some. The lateral temporal opening is separated in the teleo- 

 saurs from the orbits by an unmodified postorbital bar immediately 

 below the skin. In the broader-faced amphicoelian and in all the 

 procoelian types it is a cylindrical bar with a considerable space be- 

 tween it and the skin. The postoptics (Fig. 69 d, ao) are fully ossi- 

 fied, extending from the basisphenoid to the frontals. There is no 

 ossified interorbital septum. An antorbital vacuity is often present 

 in the teleosaurs, but only rarely has been found in the early pro- 

 coelian types. The nasals may or may not separate the external 

 nares, connecting with the premaxillae ; they are divided by a carti- 

 laginous septum in life. The nares are always at the extremity of the 

 face, no matter how long and slender it may be. There is a eusta- 

 chian canal connecting with the otic sinuses, in the median line be- 

 tween the basioccipital and basisphenoid. 



The most important modifications of the crocodilian skull are 

 found in the palate, distinguishing these reptiles from all others. The 

 maxillae meet broadly in the middle line, excluding the prevomers 



