u6 AMERICAN PERMIAN VERTEBRATES 



visible from above; their orifices looking somewhat downward. 

 The premaxillae project strongly forward and upward to meet the 

 projecting nasals. The skull also is deepest in front of the orbits, 

 indicating a large nasal cavity, which perhaps may have been of 

 service in the same way that the large nasal cavity of Ambly- 

 rhynchus is; indeed, in general shape the skulls of these two animals 

 have a curious resemblance. The premaxillae, which were found 

 attached to each other and somewhat disconnected from the maxil- 

 lae, have each two large teeth, in the articulated position directed 

 downward and not at all forward. The narrow plate back of them 

 is nearly horizontal, while the attenuated nasal processes, as stated, 

 curve upward and forward. The maxillae are broad and stout 

 in front, narrower and thinner below the orbits. Each has nine 

 teeth, the four posterior ones small. The occiput is broad, slop- 

 ing downward in the middle, and is markedly concave from side 

 to side. The roof bones of the skull, doubtless the dermoccipitals, 

 extend downward and backward broadly in the middle to the upper 

 margin of the foramen magnum; the rounded and thickened border 

 each side roofing over a narrow post-temporal vacuity. The 

 occipital condyle is small, with a distinct pit in the middle, and, as 

 in other American Permian reptiles, is composed exclusively of the 

 basioccipital. The foramen magnum is rather large, bounded 

 broadly on the sides by the exoccipitals, above by the cartilage 

 supraoccipital. The exoparoccipitals 1 form broad, gently concave 

 plates, articulating distally with the underside of the angular roof 

 extensions, doubtless the tabulare or squamosal. The quadrates 

 are visible for most of their extent. They are, as in other Texas 

 Permian reptiles, somewhat fan-shaped bones sloping downward, 

 inward, and forward, the upper margin articulating with the roof- 

 bones in front of the broad paroccipital, and probably also with 

 the distal end of the same bones. They reach anteriorly nearly 

 as far forward as the hind margin of the orbits. Their cotylar 

 surface is transverse, broader internally than externally. 



The palate bones are so much confused in the specimen that only 

 the more important characters can be made out. The vomers are 



1 V. Huene is in error in saying that the term paroccipital was proposed by Huxley. 

 It was proposed by Owen in 1838 and should take precedence over opisthotic, a term 

 iintroduced by Huxley many years later (1864). 



