576 Williston — New Genera of Permian Reptiles. 



slight inclination forward. The mandibles have a considerable 

 depth posteriorly, but are thin, and can have only a single row 

 of teeth. Back of the orbits the thickened, smooth border of 

 the anterior inferior angle of the temporal opening is apparent. 

 The structure here was probably much like that of Edajpho- 

 saurus, the lower bar broader and the quadrate in all proba- 

 bility not descending so low. Above, posteriorly, only the 

 impressions of the roof bones with clinging fragments are pre- 

 served. The region here is similar to that of Edaphosaurus. 



Fig. l. 



Fig. 1. Skull of Glaucosaurus megalops, from side and from above. 

 Natural size. No. 603, University of Chicago. 



The orbital margins are rather prominent, and the frontal 

 region between them is concave. The sutures, so far as they 

 have been made out, are shown in the drawings. 



In the general shape of the skull Glaucosaurus seems to 

 resemble Tetraceratops Matthew, from the Permian of Texas, 

 but the genus differs markedly in the absence of rugosities for 

 nasal and frontal horns, and especially in the teeth. Moreover, 

 the orbits are much larger. Two or three genera of Permian 

 reptiles from Texas are yet known only from skeleton bones, 

 and there is a possibility that some one may eventually be 

 found to be identical with the present, but, upon mature con- 

 sideration, I believe that the probability is very slight. 



One wonders what the habits of this creature, with such 

 extraordinary eyes, could have been. Possibly it was crepus- 

 cular in habit, and probably a rock climber, that the genus 

 must be classed with the so-called a Pelycosauria" or Thero- 

 morpha is evident, but closer relationships among the extra- 

 ordinary diversity of the American reptiles can at present be 

 but a mere speculation. 



