NOTES ON THE OSTEOLOGY OF THE SKULL OF 

 PARIOTICHUS 



E. B. BRANSON 



The University of Missouri 



In the summer of 1910 Dr. S. W. Williston asked the writer to 

 study the Pariotichus skulls in Walker Geological Museum of the 

 University of Chicago to see if they would throw any light on some 

 of the undecided points concerning the osteology of that genus. 

 The material was fragmentary with the exception of one remark- 

 able specimen of Pariotichus laticeps Williston, a skull of Parioti- 

 chus aguti Cope ?, and the base of a skull of an unidentified species. 

 Some of the undecided questions were: Are squamosal and pro- 

 squamosal both present? Is there a distinct quadratojugal ? 

 What are the homologies of the tabulare, if such a bone is present ? 

 What are the homologies of the so-called epiotics, quadratojugals 

 of Case ? Is a presphenoid present ? and What is the arrangement 

 of the bones in the base of the skull ? 



The writer's thanks are due Dr. Williston for the use of the 

 specimens and for discussions during the investigation. 



In a paper published in 1878 1 Cope gave the name Pariotichus 

 brachyops to an imperfect skull from the Permian of Texas, and 

 later in the same paper described a more perfect skull as Ecto- 

 cynodon ordinatus. As he supposed that the former had the roof 

 of the skull unsculptured he referred the specimens to different 

 genera. In 1882 he described Ectocynodon aguti 2 and in 1888 Ecto- 

 cynodon incisivus? In 1896 he referred all of the Ectocynodon ts 

 to Pariotichus and named two more species, P. aduncus 4 and 

 P. isolomus. 5 In the paper where he named the latter he described 



1 Proc. Am. Philos. Soc, XVII, 508. 



2 Ibid., XX, 290. 



3 Trans. Am. Philos. Soc, XVI, 290. 



" Proc. Am. Philos. Soc, XXXV, 135. 

 s Ibid., XXXIV, 145. 



135 



