ko. 1648. CERTAIN CARNIVOROUS DINOSAURS— HAY, 365 



branch of this bone runs backward against the inner face of the max- 

 illa, its hinder extremity being hidden by the maxilla, the front end 

 of the jugal, and the base of the lachrymal. The hinder border of 

 the bone sweeps around and bounds in part the postpalatine vacuity 

 mesially. The suture between the palatine and the pterygoid appears 

 to be where drawn in fig. 1, running first directly forward from the 

 inner side of the postpalatine vacuity to a distinct ridge, then fol- 

 lowing upward and inward this ridge about 25 mm. Behind this 

 ridge the fibers of the bone are directed fore and aft ; on the ridge 

 and in front of it they are directed upward. There can be little doubt 

 that the surface behind the ridge belongs to the pterygoid; that in 

 front of it, to the palatine. 



When carefully examined, the ascending suture appears to end 

 about 20 mm. below the upper border of the plate of bone of this left 

 side. From this point there appears to be a suture that runs forward 

 some distance. Above this supposed suture the bone fibers are 

 directed forward; below it, near the ridge, they are directed upward; 

 more anteriorly they run upward and forward. The part of the 

 bone with ascending fibers is quite certainly the upper and anterior 

 portion of the palatine. One can not be certain how far forward this 

 bone extends ; it seems to reach almost to the front of the antorbital 

 vacuity, ending there in a point. It is possible, however, that it ends 

 on the border of the nasal passage about 35 mm. behind the front of 

 the antorbital vacuity. 



The bone lying above the palatine and at the front of the antorbital 

 vacuity is undoubtedly the left vomer (figs. 1, 2, numeral 37). 

 This appears to extend backward to meet the pterygoid above the 

 palatine, as drawn in the figure. If this is the case, the palatines 

 did not meet at the midline of the palate. Lambe concluded that in 

 the skull of his Dryptoscmrus incrassatus (Albertosaurus sarcophagus 

 Osborn) the palatines were in contact posteriorly. 



If the conclusions arrived at here are correct, the internal narial 

 passage was bounded inwardly almost wholly by the palatine; only 

 slightly by the vomer. In any case, the vomer takes a less important 

 part in the border of the internal nostril than it does in either 

 Sphenodon or Cyclura. In Cyclura, perhaps in lizards generally, the 

 palatines meet in the midline, thus shutting off the pterygoids from 

 the vomers. In Sphenodon the pterygoids join the vomers. In the 

 broad union of the pterygoid with the quadrate and the union of the 

 pterygoid with the vomer, Ceratosaurus appears to show closer rela- 

 tionship with Sphenodon than with the lizards and crocodiles. In the 

 crocodiles access to the supratemporal fossa from behind is cut off 

 above the paroccipital process, but not from below. 



To what extent the internal nasal passage was bounded exteriorly 

 by the palatine in Ceratosaurus can not be determined. Possibly a 



