THE SKULL OF REPTILES 79 



The Skull of the Phytosaurla. 



(Figs. 6s, 66, 67) 



The skull of the Phy tosauria is nearly uniform in general structure, 

 characterized especially by the elongated face and posterior location 

 of the external nostrils. No bones are fused in the midline, and none, 

 save the primitive dermosupraoccipital, tabulars, and supratem- 

 porals are missing. The paroccipitals, as usual, are firmly fused with 

 the exoccipitals. There is no parietal foramen. The supratemporal 

 openings are more or less depressed below the level of the parietals 

 but retain their primitive boundaries. The well-developed quadrato- 

 jugals enter into the formation of the lateral temporal openings 

 posteriorly. There is a primitive quadrate foramen between the 

 quadratojugal and the quadrate. The stapes is slender. There is a 

 large antorbital foramen bounded by the maxilla, nasal, lacrimal, and 

 jugal. 



The greatly elongated face is composed chiefly of the premaxillae, 

 which extend back to the anterior ends of the nares, with the septo- 

 maxillae intervening, in the middle. The nostrils are surrounded by 

 the large nasals and are elevated to or above the superior plane of 

 the skull. 



The bones of the palate retain their primitive relations, and there 

 are small posterior palatine vacuities, larger in the more primitive 

 forms. The pterygoids meet broadly in the median line, forming the 

 roof of a deep respiratory channel between the heavy, underarching 

 palatines, in some almost forming an incipient secondary palate, in 

 the phytosaurs, as in the crocodiles, doubtless caused by the large 

 flat tongue. The interpterygoidal opening and parasphenoid are 

 small. 



The elongate prearticular of the mandible is fused with the articu- 

 lar. As usual in slender-jawed reptiles with a long symphysis, the 

 splenial participates in it, an acquired character. The condition of 

 the coronoid is not yet definitely determined, but it is doubtless 

 present, though small. A large foramen, so generally characteristic of 

 the Archosauria, is constant in the outer wall of the mandible be- 

 tween the surangular, angular, and dentary. 



The teeth are numerous, set in deep sockets and confined, as in 

 other archosaurians, to the premaxillae, maxillae, and dentaries, 



