A NEW GENUS AND SPECIES OF AMERICAN 

 THEROMORPHA 



MYCTEROSAURUS LONGICEPS 



S. W. WILLISTON 



University of Chicago 



The past summer, Mr. Herman Douthitt^ of the University of 

 Chicago paleontological expedition, discovered on Mitchell Creek, 

 Texas, in the horizon that has yielded various specimens of Pantylus 

 and the type specimens of Broiliellus and Glaucosaurus , a broken 

 skull and parts of the skeleton of a small reptile which, at the time, 

 were thought to belong to the genus Varanops. Although it 

 resembles that genus in shape and general characters, a more care- 

 ful examination disclosed a new and peculiar form of Theromorpha. 



The specimen is of a nearly white color, inclosed in a rather hard, 

 siliceous red clay, from which the bone readily separates, leaving 

 impressions as though made in wax. The skull had suffered a 

 little from compression, but is otherwise undistorted. It was origi- 

 nally quite complete, but, as found, some of the bones had separated 

 from the matrix and been lost; and the tip of the premaxillae was 

 gone. This partial loss of the bony structure, on one side or the 

 other, while detracting from the appearance of the specimen, has 

 made vividly apparent nearly every suture; others are clearly 

 shown in the bone itself. The sutures of the inner side of the 

 cranial bones are not always quite the same as on the outside; as an 

 instance of which, the shape and size of the postfrontal of Pantylus 

 is quite as Case and Huene figured it, while on the outside Broom 

 gave the form correctly ; and the quadrato jugal of the same genus is 

 nearly twice as broad on the inside as on the outside. In the figures 

 given herewith (Figs, i, 2) I have widened the face a little in top 

 view, perhaps not quite enough. I have depended in no instance 

 on any line indicating a suture unless it is precisely corroborated 

 on the two sides, precluding the danger of mistaking cracks for 



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