THE PHYTOSAURIA OF THE TRIAS 



^SS 



A COMPARISON OF THE GENUS AngistorhiflUS WITH OTHER 



GENERA 



AngistorhiflUS is one of the largest forms known. The skull is 

 longer than any other except perhaps that of Lophoprosopus 

 (Belodon) kapffi. The most striking difference seen between these 

 two forms is in the rostrum. In Lophoprosopus there is a high, 

 vertical swelling or crest extending almost the entire length, while 

 in Angistorhinus the rostrum is low and slender. In this form, too, 

 the anterior extremity is abruptly turned down, much more so than 



Figs. 17-18. — Angistorhinus gracilis, anterior and lateral views of one of the 

 anterior thoracic vertebrae, about one-third natural size. 



in Lophoprosopus. Another important difference is seen in the 

 well-developed parieto-squamosal arcade lying in the plane of the 

 dorsal surface of the cranium of Angistorhinus and the much- 

 reduced, depressed post-temporal arcade of Lophoprosopus that 

 gives the supratemporal fenestra the appearance of being open 

 behind. 



From Mystriosuchus the genus differs, not only in the develop- 

 ment of the post- temporal arcade in the manner mentioned above, 

 but also quite radically in the teeth. In Mystriosuchus there are 

 94 of these in the upper dentition and not more than 84 in the upper 

 dentition of Angistorhinus. In the latter genus, as pointed out 

 above, the posterior teeth are laterally compressed with sharp 



