F. von Huene — Order Thecodontia. 23 



not go generically with the older animal described by 

 Marsh as Stegomus arcuatus (see also 13 ), which I now 

 take for a primitive Parasuchian. Therefore I propose 

 to call the former Stegomosuchus (n. gen.) longipes and 

 its Psendosuchian family Stegomosuchidse (n. fam.). 



The classification of the Parasuchia is mostly based 

 npon features of the skull. The essential points are: 

 relative length of the base of the skull, relative length of 

 the snout, position of the narial openings, condition of 

 the supratemporal opening, and palate. The posterior 

 part of the skull (beginning in front with the anterior 

 margin of the nares) in different genera has a relative 

 length of from 48 to 33.3 per cent of the whole skull. 

 In some very primitive genera, however, it cannot yet 

 be measured as the tip of the snout is missing in the 

 known specimens. 



The Parasuchia may be classified in the following 

 manner : 



Desraatosucliidag Desmatosuclius 



(Mesorhinus 



Stagonolepidae -j Stagonolepis 



{ ? Stegomus ( arcuatus ) 

 Phytosauridse Phytosaurus 



Angistorhinus 



Palceorhinus 



Alachceroprosopus 



Rutiodon 



Wpiscoposaurus ' 



Warasuchus 



Riley a 



Angistorhinopsis, n. gen. 



Mystriosuchus 



The Desmatosuchidae and the Stagonolepidas I regard 

 as the most primitive families, of not later than Middle 

 Triassic age. The European f Phytosaurus I take as 

 a persistently primitive form retaining an early stage of 

 Parasuchian evolution in the very long posterior part of 

 the skull and the dermal armature. But the shifting 

 backward of the supratemporal groove and the short base 

 of the skull nevertheless indicate a terminal member of 

 this branch of the Parasuchia. The Mystriosuchidse are 

 a big group which probably in the future will be divided 

 into at least two families, as their feet show very different 



Mvstriosuchidas 



