14 THE EXTINCT BATRACHIA, REPTILIA 



BRACHYDECTES, Cope. 

 Proceed. Ac. Nat. Sci., Phila., 1868, 214. 



This genus is indicated by two rami of a mandible and a portion of a premaxillary 

 only. These, when compared with those of GEstocephalus, and Dendrerpeton, from the 

 same locality, and with others described by authors, are so much stouter, i. e., shorter 

 and more elevated, that they evidently belonged to a genus not hitherto known. The 

 genus further differs from Oestocephalus, in having the teeth of equal size to the poste- 

 rior parts of the series, that is, to the base of the elevated coronoid process. The teeth 

 are elongate cylindric cones, with their acute tips turned a little posteriorly. The frac- 

 tured ones display a large pulp cavity. The three premaxillaries preserved are similar, 

 but without curvature of the tips. They do not exhibit strise or any other sculpture. 



So far as the remains known go, the genus is nearer Hylerpeton than any other. 

 According to Dawson that genus is provided with a large canine-like tooth, at the ante- 

 rior extremity of the maxillary, on the inner row, which is inserted into a distinct socket. 

 No such tooth appears among those of this genus. The latter does not give any indica- 

 tion of the very elevated coronoid process of Brachydectes, though the external portion 

 of the dentary bone in that region being lost, little can be said about it. Prof. Owen's 

 plate indicates a ramus whose depth at the last tooth enters 8| times the total length. 

 In our species this depth enters about 5 times. 



BRACHYDECTES NEWBERRYI, Cope. 



This species is represented by one nearly perfect ramus mandibuli, one dentary bone, and one premaxillary, prob- 

 ably not complete. 



The dentary bone appears to have been attached by suture to the articular and angular, as its free margin has 

 very much the outline of that suture in Amphiuma and lizards. The coronoid process would also seem to be a part 

 of the same bone as in Amphiuma and Menopoma, and not composed of a coronoid bone as in lizards. It rises im- 

 mediately behind the last tooth, and displays no suture. 



The lower portion of the dentary is prolonged into an acute angle. This is separated by a deep and wide con- 

 cavity 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 

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

 These teeth are the longest of the Microsauria in relation to the depth of the ramus, equalling the largest in (Estc- 

 cephalus. 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 aerodont, 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. 



