THE UPPER TRIASSIC OF WESTERN TEXAS. 



19 



The inner end of the anterior process rises from a triangular base. From the 

 center of the posterior end of the groove on the palatine ramus of the pterygoid a thin 

 wall rises obUquely backward; beneath this there is a deep pit, with its mouth just 

 anterior to the outer end of the arch described on the parasphenoid. This pit extends 

 obliquely backward and its apex is perforated by two small foramina on the left side; 

 the pit on the right side is perforated by a single foramen. Posterior to this pit the 

 base of the process is thickened (fig. 2 b) just opposite the anterior edge of the outer 



Fig. 2. — Buettneria perfecta. 



A. Upper (inner) view of the bones 



of the basicranial region. 

 d.sq., descending process of 

 the squamosal; i.e., open- 

 ing of cavity for the inter- 

 nal carotid artery; i. 

 outlet for the tenth cranial 

 nerve. Other lettering as 

 in figure 1. 



B. Upper view of the left quadrate 



ramus of the pterygoid. 

 Lettering as in previous 

 figures. 



opening of the arch on the parasphenoid ; beneath it a second pit passes forward and 

 slightly inward and is imperforate. The apices of the two pits are separated by a 

 thin wall. The third part of the triangular base is formed by the lower part of the anterior 

 rising process. The upper part of this rising process is somewhat crumpled; it is impos- 

 sible to interpret the appearance exactly, for the distortion gives the appearance of 

 reduplication, as if the bone were made up of superimposed laminae or, which seems very 

 improbable, of separate thin bones. 



On the posterior edge of the quadrate ramus is the posterior rising process. Its 

 inner end originates just posterior and external to the second pit described above; it 

 reaches nearly as great a height as the anterior one, but there is no indication that it 

 was ever attached to the roof above; in the specimen there is quite a space between the 

 two. This process is shown by Quenstedt^ as reaching up to the squamosal in Cyclo- 

 tosaurus (Mastodonsaurus) robustus. Fraas.^ however, shows the plate of much less 

 height in Cyclotosaurus posthumus. Watson, in his figure after Fraas, draws it much 

 higher.^ 



The outer ends of the two processes unite apparently without suture and clasp the 

 inner and part of the posterior face of the quadrate. Into the deep cleft between the 

 two processes descends the process from the sq uamosal. The relations of these processes 



' Quenstedt, F. A., Die Mastodonsaurier im grunen Keupersandsteine Wurtemberg's sind Batrachier, Tubingen, 



1850, pi. 3, fig. 16. 

 ''Fraas, E., Neue Labyrinthodonten aus der Schwabischen Trias, Paleontographica, Bd. lx, pi. xviii, fig. 2, 



1913. 

 s Watson, D. M. S., loc. cit., fig. 30 c, p. 54. 



