LYSOROPHUS, A PERMIAN URODELE. 



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the frontals with nearly parallel sides, overhanging, for the most 

 part, the open temporal region. There is no parietal foramen. 

 They are gently convex from side to side. From this posterior 

 suture the upper surface of the skull turns downward at an angle 

 of about twenty degrees, so as to bring it nearly parallel with the 

 plane of the lower margins of the mandibles. Three rather 

 large bones are seen here, a median unpaired one and two larger 

 lateral ones. The median bone is broader in front than behind 

 and borders the large foramen magnum ; it doubtless corresponds 

 to the median cartilage found in many urodeles, called the supra- 

 occipital usually, by Gaupp the tectum synoticum. The lateral 



Fig. I. Lysoropkus iricariuatus, skull from above, enlarged three diameters. 



bones are larger, of an irregularly square shape with a hook-like 

 prolongation exteriorly behind, turned downward back of the 

 squamosal. They must be identified as "epiotics," a bone rarely 

 if ever found separate in the modern batrachians. The squa- 

 mosal (paraquadrate of Gaupp) unites, by a nearly straight antero- 

 posterior suture, with the parietal and epiotic and then turns 

 downward, forward and a little outward, narrowed and more 

 rod-like below. There is some doubt of its union with the 

 quadrate, but the division seems apparent on each side. With 

 this interpretation, the quadrates are small bones, about twice as 



