176 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



"The lower portion of the dentary is prolonged into an acute angle. This is separated 

 by a deep and wide concavity from the superior posterior prolongation, which is obtuse, 

 and rises at once into the coronoid process. Teeth on this dentary, seven ; the same number 

 is on the preserved ramus; this number is suspected to be complete, or nearly so. The teeth 

 terminate at the obvious termination of each ramus, which is, it is true, slightly obscured. 

 These teeth are the longest in the Microsauria in relation to the depth of the ramus, equal- 

 ing the largest in (Esioccphaliis. They are doubtless exposed, as are some of those of the 

 last-named genus, by the splitting away of the outer parapet of the dentary bone. As no 

 traces of alveoli have been thus rendered visible I suspect the dentition to have been 

 acrodont, as in some existing Batrachia. 



" No external surface of the mandible remains, but there are no impressions of sculpture 

 on the matrix. A little external face of the premaxillary displays none. 



" The species is dedicated to Professor John S. Newberr>', the able director of the Geo- 

 logical Survey of Ohio, and discoverer of most of the Batrachia herein described." 



Measurements of the Type. 



mm. mm. 



Length of ramus of mandible (imperfect) 22 Length of dentary 16 



Depth at last tooth 5 Depth at coronoid process 7.5 



Length of exposed tcoth 3.5 Depth at first tooth 3 



Genus PROTERPETON new genus. 



Type: Proterpeton gurleyi Moodie. 



Known from a single vertebra. Spine very high and heavy, the neural canal 

 large. 



Proterpeton gurleyi new species. 



Type: Specimen No. 13,296, Walker Museum, University of Chicago. 



Horizon and locality: Coal Measures near Danville, Illinois. 



The vertebra, as preserved, is well characterized by the figure (plate 22, fig. 2). 

 The spine is high and heavy, the neural canal is large, and the centrum reduced. 

 The form is very unusual. It is apparently from the cervical region, as there are no 

 indications of zygapophyses, transverse processes, or haemal arches, although they 

 may have been abraded; apparently not, however. The type specimen was dis- 

 covered near Danville, Illinois, about the horizon of the Danville coal, so that it is 

 quite high in the Allegheny series of the Pennsylvanian and of about the same 

 horizon as the phalangeal bone from Breeze, Illinois, which may be provisionally 

 associated with this form. There is no assurance that Proterpeton gurleyi is an 

 amphibian. The vertebra may have belonged to a fish. 



Measurements of the Type of Proterpeton gurleyi Moodie. 



mm. mm. 



Entire height of vertebra 24 Height of neural canal (cnished ?) 6.5 



Width at side of neural canal 21.5 Width of vertebral centrum anteroposteriorly 5.5 



Width of neural canal 13 Height of neural spine from top of neural canal ... 9 



Genus AMBLYODON Dawson, 1882. 

 Dawson, Phil. Trans. Roy. Soc. London, pt. 11, p. 644, pi. 40, figs. 57-61, 1882. 



Type: Amblyodon problematicum Dawson. 



This genus was described by Dawson in 1882 from very imperfect remains. He 

 says that it is "characterized by stout cylindrical teeth, blunt at the apices; but 

 otherwise imperfectly known." 



