Cope.] 460 [Sept. 15, 



wards, and below upwards. This is totally difierent from what is observed 

 in the other known species of Eryopidm, Trimerorhachida;, and Diplocau- 

 lidoe. The teeth are round in section, but become lenticular near the apex, 

 developing low cutting edges. The basal grooves are fine, but distinct, 

 and extend half way to the apex, or farther. One large, and one medium 

 sized teeth stand on each dentary bone near the symphysis, and there are 

 two similar ones at a point further back on the same bone. Near the an- 

 terior part of the maxillary, below the ? nostrils, is a huge tooth, with a 

 graduated series of small teeth posterior to it, and a very small one ante- 

 rior to it. 



The neural arch of a vertebra has a well developed vertical spine. Its 

 neurapophysis rested in an oval fossa of the centrum which probably was 

 divided into pleurocentra. The prezygapophyses are very small, and look 

 directly upwards. The postzygapophyses are much larger, and look 

 obliquely outwards and backwards. The spine is not expanded at the 

 summit, and is granular, as though it was protected by a cartilaginous 

 cap. Its section is anteroposteriorly lenticular, with acute edge (angle) 

 posteriorly, and a very narrow truncate edge ante^iorlJ^ The latter is 

 bounded below just above the root of the neural arch by two little fosste. 

 The posterior keel is bounded below by a corresponding single fossa. The 

 posterior acute edge of the spine is dentate, and the surface on each side 

 of it, is beveled with rabbeted surfaces as though for a coarse squamosal 

 suture. But the appearance of suture is fallacious, and is simply due to 

 contraction of the transverse diameter of the spine. The neurapophysis 

 is much narrower anteroposteriorly than the neural spine. 



Measurements. M. 



Depth of maxillary bone at large anterior tootli 037 



" dentary at symphysis 025 



" " near middle 021 



Width " " " 015 



Diameter of base of large maxillary tooth 010 



" " small maxillary tooth 0035 



Length " " " " 008 



" of large mandibular tooth near symphysis 016 



Diameter of base of crown of do 006 



Elevation of neural arch. 037 



f vertical 029 



Diameters neural spine < . ^ anteroposterior 019 



l ^^ *P*^^ I transverse 012 



Width neurapophysis anteroposteriorly 010 



From Mr. W. F. Cummins' collections. 



I had thought at one time that this species might be referable to the ge- 

 nus Leptophractus of the Coal Measures. No trace of the vertebrae of the 

 Rhachitomous order has yet been found in that formation in this country, 

 nor have any of the Coal Measure genera of Batrachia yet been found in 



