ANGISTORHINUS, A NEW GENUS OF PHYTOSAURIA 189 
58): ‘‘In this specimen [a specimen of R. carolinensis from the U.S. 
Nat. Mus.] the broad superficial portion of the post-fronto 
squamosal arcades is broken away, exposing the supratemporal 
fenestra and the parieto-squamosal arcade. If uninjured this 
portion of the skull would closely resemble that of Mystrio- 
BUUGNUS: 35.5 id 
There is no good basis for the comparison of Angistorhinus with 
Phytosaurus (Heterodontosuchus) ganei Lucas,‘ as until recently only 
the anterior part of an imperfect mandible of the latter form was 
known. In this, according to Lucas, the teeth were separated by a 
thin film of bone only, while in Angistorhinus they are separated by 
a distance of from 4mm.to8mm. Furthermore, the examination 
of more recently obtained material suggests, at least, that Hetero- 
dontosuchus belongs to the genus Phytosaurus (McGregor, op. cit., 
p- 94). In this case the differences in the posterior border of the 
skulls would exist as pointed out above. 
‘Angistorhinus differs from Paleorhinus bransoni Williston’ in 
many minor points such as the greater posterior width of the skull 
in the former, the greater lateral extent of the opisthotics, the larger 
openings in the skull, the abrupt downturning of the anterior end 
of the rostrum, and the much more massive build of the skull 
throughout. Most important of the differences, however, is the 
more primitive, that is, the more anterior position of the external 
nares in Paleorhinus. In that form the posterior border of the nares 
lies fully 30 mm. in front of the anterior borders of the antorbital 
vacuities, while in Angistorhinus the anterior border of the nares is 
about even with the anterior borders of the antorbital vacuities. 
While Angistorhinus resembles Mesorhinus Fraasi Jaekel’ in the 
form and development of the parieto-squamosal arcade, the two 
forms differ markedly in that the latter possesses a parietal foramen, 
according to Jaekel, and has the external nares more anterior in 
position. The downward process from the upper posterior side of 
the squamosal seems to be lacking in Mesorhinus, and the basi- 
t Amer. Jour. Sci. (4), VI (1808), 309. 
2J. H. Lees, Jour. Geol. XV, No. 2 (1907). 
3 “Uber einen neuen Belodonten aus dem Buntsandstein von Bernburg,”’ Si/swngs- 
berichten der Gesellschaft Naturforschender Freunde, No. 5, Jahrgang 1910. 
