NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 



137 



Labidosaurus (fig. 22). — This animal shows somewhat the same relations 

 to Captorhinus that Limnoscelis does to Diadectes. It was a more aquatic 

 form, with a flatter skull, having the orbit and nares near the upper surface. 

 The teeth were far better formed and the carpus and tarsus better ossified 

 than were those of Limnoscelis. The tail was only moderately long. It is 

 probable that Labidosaurus was equally at home on the land and in the water, 

 but not capable of very rapid movement in either. Upon the land it must 



Fig. 22. — Restoration o£ Labidosaurus hamatus Cope. About one- third natura size. 



have occupied a prone position most of the time, and probably never rose to 

 a position so erect as given to it in Broili's reconstruction. The remains most 

 commonly found indicate an animal of a meter or less in length, but a few 

 skulls have been found which belonged to animals nearly twice that size. As 

 suggested in the discussion of the food habits, it probably fed upon softer or 

 less well protected animals than did Captorhinus. The incisors were too 

 sharply turned backward to have ever been useful as weapons of offense or 

 defense, but would have been very efficient in extracting burrowing creatures, 

 or those hidden in cracks or crevices in the rocks, or tearing loose clinging 

 forms. Labidosaurus was one of the great group which clung to the margin 

 of the pools, or lived in the damp places among an abundant vegetation. 



Seymouria (fig. 23). — This is one of the most puzzling of the Permo- 

 Carboniferous reptiles. It is so primitive in many of the characters of the 



Fig. 23. — ^Restoration of Seymouria baylorensis Broili. About one-fourth natural size. 



skull and skeleton that it is considered by Williston to be the nearest dis- 

 covered form to the connecting-link between the reptiles and amphibians. 

 The body was fairly plump, with strong limbs and rather slender digits, the 

 tail being relatively short. Williston detected certain flakes of bone scattered 

 through the matrix immediately adjacent to the bones, which he thinks are 



