238 CASE. [Vol. II.. 



basisphenoid (presphenoid) : the edges of this vacuity are cov- 

 ered with small teeth set closely together. The posterior proc- 

 ess is also broad and plate-like ; it extends back to the quadrate 

 which it joins ; it is set at something of an angle with the rest of 

 the bone. The third process is not so distinct from the rest of 

 the bone as in the Pelycosaaria; it is virtually a thickening 

 of the posterior edge of the anterior process, but this is carried 

 to a degree that demands description as a separate process. It 

 extends directly outward from a point opposite the middle por- 

 tion of the bone ; the posterior edge is sharp and abrupt, while 

 the anterior side slopes down gently to join the rest of the 

 bone ; this slope is covered with a patch of small blunt teeth, 

 very closely set together ; the patch is separated from the patch 

 upon the borders of the median vacuity by a shallow groove ; it 

 is connected with the patch upon the palatine. The presence 

 of this patch of many small blunt teeth upon the external proc- 

 ess is one of the distinguishing features of the Pariotichidae, 

 for in the Pclycosaiiria the teeth upon this process are few, and 

 planted in distinct sockets. Opposite the origin of the exter- 

 nal process there is developed on the inner edge of the bone 

 a short blunt process, the basisphenoid process, which gives 

 attachment to the basisphenoid bone (Fig. i,//.). 



There is no trace of an ectopterygoid ; it is probable that it 

 was attached to the anterior process of the pterygoid, and did 

 not join the external process except at the anterior side of the 

 extreme end. 



The basisphenoid is much as in other primitive reptiles, with 

 the characteristic groove on the lower surface, between the 

 basipterygoid processes ; the anterior end is continued as a 

 long and slender process (presphenoid), which extends into the 

 median vacuity between the pterygoids. 



The posterior portion of the base of the skull is obscured by 

 the crushed anterior cervical vertebrae and the distortion accom- 

 panying fossilization. A distinct opisthotic can be made out, 

 and anterior to this a long slender element that appears to be 

 a stapes. The basioccipital is completely obscured. The quad- 

 rate is covered by the bones of the temporal region and the 

 articular portion of the lower jaw, but enough can be made out 



