60 NEW REPTILES AND STEGOCEPHALIANS FROM 



The figures show this specimen as having no interpterygoid vacuity and no parasphenoid; 

 this is, in all probability, the result of the condition of the specimen. There is an elevated 

 rim to the- external nares, and the septum is at the level of the top of the skull. By 

 utiUzing a specimen in the New York State Museum, which he assumes to have been of 

 the same size as the one in the American Museum, McGregor determined the prenarial 

 and postnarial proportion to be as 3 : 2. 



Comparison with Phytosaurus (Mach^roprosopus). 



The specimen described as Machceroprosopus by Mehl^ and regarded by him as 

 congeneric with Belodon buceros Cope is in many ways intermediate between the Mystrio- 

 suchid and the Phytosaurid groups of the Parasuchia. The elevation of the posterior 

 half of the rostrum, the posterior position of the nares, and the extreme depression of 

 the parieto-squamosal arch are all characters of the Phytosaurid group, while the long, 

 slender anterior half of the rostrum is distinctly Mystriosuchid-like. The prenarial 

 portion of the rostrum is relatively short, its proportional length to the postnarial portion 

 being as 7.8 : 8.3, or a little less than 1:1; the antorbital opening is elongate and reaches 

 almost to the anterior end of the extemi nares; the parietals have no posterior bar, and 

 the squamosal region is much extended, reaching far behind the condyle; the supratem- 

 poral openings look almost entirely to the rear; MehP has drawn in outline a rather 

 broad bar separating the supratemporal from the post-temporal openings on the posterior 

 surface of the skull. This is probably correct, as its width is indicated by the broken 

 edges, but, if so, it leaves a much larger post-temporal opening than occurs in any other 

 of the Phytosaurid group. 



1 Mehl, M. G., Quarterly Bulletin University of Oklahoma, n. s., No. 103, 1916. 

 ' Mehl, M. G., loc. cit., fig. 3. 



