PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



75 



The skull is about as complete as the genotype, with the exception of the man- 

 dible, of which nothing has been detected. Like that specimen, it is crushed nearly 

 flat. By careful labor the broken parts have all been reunited, and the whole has 

 been carefully cleaned of its investing matrix; unfortunately some fragments were 

 not recovered. The skull is shown in fig. 47, as carefully drawn by Williston. 

 The upper side resembles in its proportions the original type better than it does 

 that of the skull described on the preceding pages, especially so in the relative 

 widths of the interorbital and interparietal regions. 



On the palatal side the two large plates bearing the teeth are nearly complete, 

 that of the right side quite so. About seventy -five teeth are visible on this side; 

 possibly there are a few more. The teeth vary not a little in size. They are 

 hemi-ellipsoidal in shape. The more newly erupted, smaller ones have the apex 



Fig. 47. Edaphosaurus novoniexieanus Williston and Case, X J^. A, skull 

 from above; B, skull from below; bo, basioccipita!; bs, basisphenoid; 

 ep, epipterygoid; po, paroccipital; pi, pterygoid; q, quadrate. 



somewhat pointed, but most of them are worn a little at the top. They are inserted 

 in pits, thecodont, or protothecodont. The anterior part of the plate is angulated 

 somewhat from the larger posterior part, about in the place where Broom thought 

 the palato-pterygoid suture occurs; possibly the angulation indicates a suture, 

 but that can not be determined. The maxillary teeth extend back to about the 

 middle of the pterygo-palatine teeth, and beyond the middle of the orbit. There 

 is no evidence of a posterior palatine vacuity; there is certainly none in the place 

 figured by Broom in his restoration. The region in front of the middle is injured 

 in the specimen, and its structure can not be made out; there are no vomerine teeth 

 visible. 



Posteriorly the basisphenoid has a deep median fossa, on either side of which, 

 behind, there is a descending basisphenoid process; the distal end of the stapes is 

 visible. The quadrates are visible in large part They are shaped much like tho.se 

 of the true pelycosaurs, consisting of a thin, expanded plate directed obliquely 

 forward and inward, articulating on the outer side with the lower part of the squa- 

 mosal or quadratojugal, on the inner side by a large and firm surface with the 



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