386 WilUstov — New Family of Reptiles from the 



less conical in life, but unpreservable in the preparation of the 

 skull. In front of these teeth I can find evidence of but a 

 single tooth, located as I have marked ; I am not quite sure of 

 it, but in all probability there were others. Opposite the front 

 end of the basisphenoid, the pterygoid on each side articulates 

 with a stout basipterygoid process of the basisphenoid, quite as 

 in the lacertilians, the first evidence I have seen among the 

 Permian vertebrates of a real articulation at this place. The 

 pterygoid has a pit or depression on the inner side for the head 

 of this large process. Back of these processes the pterygoids 

 resemble remarkably the like processes of the lizards, or Sphen- 

 odon, a not very wide, rather stout, obliquely placed process 

 reaching backward to articulate with the lower inner side of 

 the quadrate. In the middle the large basisphenoid is con- 

 spicuous ; unlike that of the Diadectidre, it is stout and rounded 

 below, where it gives off the basipterygoid processes. Ante- 

 riorly it gives off the so-called parasphenoid. But the " para- 

 sphenoid" in this case is a thin vertical plate, thickened poste- 

 riorly to join the anterior end of the basisphenoid, very much as 

 in Trinacromerum among the plesiosaurs. In the specimen 

 the front part lies obliquely in the matrix an inch or more in 

 width, with the lower margin, that visible in its normal posi- 

 tion, narrow. Behind the rounded median convexity of the 

 sphenoid, the bone is broadly concave in the middle, on either 

 side of which the usual basisphenoid process is directed down- 

 ward, backward and outward, to end in a rather stout projec- 

 tion. In the middle of this concavity the sutural line for union 

 with the basioccipital is evident. The occipital condyle is 

 quite flat or even concave, as in Diadectes and Pareiasaurus, 

 a strong indication of relationship. On either side of the basi- 

 occipital I think I have interpreted the bones of the posterior 

 palatal and occipital regions, but I prefer to wait before pub- 

 lishing my conclusions in the hope of getting material of this 

 form the coming season. 



The mandibles of Limnoscelis are very powerful, indicative 

 of the carnivorous habits of the animal in life. They lie in 

 perfect relation to each other, save that they are a little skewed 

 to the right. They are broadly separated behind, with a long 

 convexity on the sides, and again expanded at the front end. 

 The teeth are only partly visible from without ; the one or 

 more large ones in front opposing the premaxillary teeth are 

 wholly hidden, nor can the number be made out with certainty. 

 The postarticular process is small, not extending back of the 

 quadrate, or if so, but for a few millimeters only. Externally 

 the suture separating the angular from the surangular passes 

 forward near the middle of the bone, and backward nearly to 

 the extremity, On the inner side of the mandible the structure 



