AMERICAN LABYRINTHODONTID/E 



603 



the angular and prearticular directly below the anterior end of the 

 supra-meckelian foramen. The supra-meckelian foramen is elongate 

 and narrow. 



The sculpture on the outside of the mandible consists of longi- 

 tudinal ridges and furrows above, but these become coarser and have 

 more of the pitted character below. 



Fig. 13. — Eryops Cope; inner view of mandible, one-fourth natural size, 

 a, angular; d, dentary; c, coronoid; pa, prearticular; s, splenial; ?, probably a separate element. 



Sa ' "■ ' a. 



Fig. 13a.' — Eryops Cope; outer view of mandible, one-third natural size, 

 a, angular; ar, articular; d, dentary; sa, surangular. 



Vertebra. — Belonging with the skull above described there are 

 twenty vertebrae, five of which are caudals and the rest dorsals. A 

 smaller specimen, probably of Eryops megacephalus, has twenty-four 

 vertebras preserved in a continuous series, beginning with the atlas. 

 The number of presacral vertebrae can be pretty definitely determined 

 from these two specimens, and seems to be twenty-five or twenty-six. 

 There are two sacrals and about fifteen caudals. The number of 

 caudals is estimated from the anterior and posterior ones figured by 

 Cope. These specimens furnish some new and interesting facts about 

 the vertebrae of Eryops. 



The atlas is composed of the neurocentra and intercentrum, 

 the neurocentra resting firmly on the intercentrum, but not co-ossified 

 with it. The intercentrum is not divided on the middle, as Cope 



