OSTEOLOGY OF THE SKULL OF PARIOTICHUS 137 



it is distinctly separated from the parietal, but there is no indica- 

 tion of it in Labidosaurus. Cope also applied the name tabulare 

 to the element and recently Broom has suggested the name post- 

 temporal. There seems to be no valid objection to tabulare and it 

 has the advantage of priority over Broom's name. 



All writers seem to be agreed about the rest of the bones in the 

 roof of the shull. 



Base of skull. — The bases of several skulls examined during the 

 investigation were fairly well preserved and the one from which 

 Fig. 3 was made is almost perfect. This shows the post-parietals 

 in the same position as figured by Williston in Labidosaurus 1 and 

 by Case in Edaphosaurus 2 and Pariotichus. (Case calls them 

 epiotics in Edaphosaurus.) 



The exoccipitals are large and articulate with the squamosals 

 after passing in front of the inturned edge of the latter, the quadra- 

 tojugals of Case. The stapes, tympanic of Broom, articulates at 

 its distal end with the lower inner end of the quadrate. In the 

 drawing it is not shown distinctly separated from the exoccipital, 

 the sutures not having been determined. The separation in this 

 form is probably as shown by Williston in Labidosaurus. 



The position of the quadrate is almost vertical with a broad 

 bladelike process above and a heavy expanded portion below. 

 The bladelike portion projects forward almost parallel with the 

 median line of the skull, and the posterior end of the pterygoid 

 rests against it. Its upper end comes in contact with the squamosal 

 and the outer side of the base touches the quadratojugal. 



Floor of skull. — The pterygoids extend from near the posterior 

 end of the skull almost to the anterior end. They meet in the 

 median line and are not separated by the basisphenoid as shown 

 by Broom in Pariotichus angusticeps Cope. 3 The sutures between 

 the long slender palatines and the pterygoids were made out in 

 one specimen from the anterior end to near the posterior end, as 

 shown by solid lines in the drawing. There are strong indications 

 of a transverse as shown by broken lines in Fig*. 4, but the evidence 



1 Amer. Jour. Anat., X, PI. Ill, Fig. 4. 



2 Revision of the Pelycosauria of North America, 1907, p. 153. 



3 Bull. Am. Mils. Nat. Hist., XXVIII (1910), 218. 



