144 MAURICE G. MEHL 



the lower border of the foramen magnum. The part they take in 

 the formation of the occipital condyle, I take it, is slight. The 

 opisthotics are rather stout and widen considerably toward their 

 lateral extremities. Just before they reach the hooklike processes 

 of the squamosals their vertical measurement is about 38 mm. 

 From this point they rapidly taper off in each direction. They 

 form the lower and apparently the inner borders of the post- 

 temporal vacuities. The relations of the pterygoids with the quad- 

 rates seem to be much the same as in M. planirostris, according to 

 McGregor's interpretation. Their later?! extent on the posterior 

 surface of the skull ; - s to be -^ -aparativel'^ slight. There is no 

 possibility of theii ' xg ^^art in the boi ^r-^ of tlie' quadrate' 

 foramina as they uo m Belodoff (Mystrios^onus) 'plienmgeri H. 

 von Meyer sp., according to F, von tluene.^ In the specimen 

 herein described the lower lateral portion of t^'e quadrate was 

 broken away, leaving, however, a good impression of the inner 

 surface. From this and the natural mold in the matrix, of the 

 outer surface, and with the aid of a separate quadrate found in 

 the same locality, an accurate restoration was possible. It has an 

 articular face of about 75 mm. lateral extent. There is an offset 

 in the quadrate along a vertical line through the inner limit of 

 this articular face. From this offset it extends toward the median 

 hne in a thin plate. Its inner edge meets the pterygoid and the 

 two floor over a depression, the outline of which is a parallelogram 

 with the greater diagonal directed upward and inward. This 

 depression is bounded above by the opisthotic, on the outer side 

 by the raised portion of the quadrate, below by the raised barlike 

 portion of the cojoined quadrate and pterygoid, and on the inner 

 side by the exoccipitals and the basisphenoid. 



THE MANDIBLE 



The mandible of this species is massive throughout. This is 

 especially noticeable in the posterior symphysial region; here the 



' For an explanation of the substitution of BeJodon for Mystriosuchus see the 

 appended Hst of genera and species. 



=^"Beitrage zur Kenntnis und Beurteilung der Parasuchier," Geologische and 

 palaeontologische Ahhandlungen, Neue Folge, Band X, Heft I (1911), p. 8, Fig. 3. 



