No. 5.] 



PARIOTICHUS INCISIVUS COPE. 



237 



to this tooth the teeth become smaller and more irregular 

 in position ; they are smooth and without anterior and posterior 

 cutting edges. The teeth of the mandible and the premaxil- 

 lary are as described by Cope, with the exception that in the 

 posterior part of the mandibular series only are the teeth 

 arranged in more than one row. The dentine of the enlarged 

 internal incisor of the premaxillary shows some indication of a 

 radial arrangement of the dentine. 



The upper surface of the skull is so injured that it is impos- 

 sible to make out the exact relations of the bones, but their 



Fig. 



■Upper and lower surfaces of skull. The extent of the lachrymal is adapted from 

 Cope's figures, but is indicated in the present specimen as well. 



general arrangement is shown in Fig. i, in part suggested by 

 Cope's figures. The character of the sculpture in the occipital 

 and parietal regions is shown in Fig. 2. 



The lower surface of the skull shows the general arrangement 

 of the bones characteristic of the Permian reptiles ; teeth are 

 present in patches upon the vomer, palatines, and pterygoids. 

 The pterygoids show the tripartite form characteristic of the 

 Pelycosaiiria ; the anterior process is broad and plate-like, and 

 the anterior part of each bone joins that of the opposite side 

 in the middle line ; more posteriorly they diverge and form a 

 vacuity, into which projects the stylus-like anterior end of the 



