14 



THE EXTINCT BA'TRACHIA, REPTILIA 



BRACHYDECTES, Cope. 



Proceed. Ac. Nat. Sei., 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 CEstocephalus, 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. 'Hie teeth 

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

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

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



So fu- as the remains known go, the genus is nearer Eylerpeton 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. 'Hie latter does not give any indica- 

 tion of tin- 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. 



BR ACH YDECTE 8 N E W 1 ! B 1 1 1 1 Y I , Cope. 



This species is represented by one nearly perfect ramus tnandlbuli, 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 An, phi, mi;, and lizards. The coronoid process would also seem to he a pari 

 of II, e same bone as in Amphiuma and Menopoma, and not composed of a, cor >id bone as in lizards. It, rises im- 

 mediately behind the last tooth, and displays no si, tore. 



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

 cavity from the superior posterior prolongation, Which is obtuse and rises ;,l, once into the coronoid process. Teeth 



on ibis dentary seven ; the same number is on the preserved ramus; this number is suspected to be complete or 

 naerlyso. 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 Oto- 

 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 hone. As no traces of alveoli have been thus rendered visible, 1 suspect the dentition 

 to have been aorodont, as in some existing BatraoHa. 



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. 



