l66 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



Genus CTENERPETON Cope, 1897. 

 Cope, Proc. Am. Phil. Soc., xxx\-i, p. 83, pi. iii, fig. 1, 1897. 



Type: Ctenerpeton alveolalum Cope. 



The genus Ctenerpeton was founded by Cope for the reception of a single species 

 which presents some very unusual characters. The form shows close relationships 

 to the genera Urocordylus (334), CEstocephalus, and Ptyonins. These genera agree 

 with the present one in the possession of very characteristic vertebrae which are 

 signalized by the elongate and ornamented characters of the neural and haemal 

 spines. These project prominently from the body of the vertebra and have the 

 ends of the projections truncate and divided into fine points, thus causing the spine 

 to have much the appearance of a comb. The surface of the neural spine is some- 

 times marked with a shallow groove. The spines are longer and more slender in 

 the genera CEstocephalus, Urocordylus, and Ctenerpeton than they are in the species 

 of the genus Ptyonius, where they are short, although the usual pectinations are 

 present. 



The character on which this genus rests is the shelf -like extension (plate 23, fig. 2) 

 of the abdominal plates. This is of a very unusual character and entirely unknown 

 in any other species of Carboniferous Amphibia. The term Ctenerpeton has reference 

 to the fact that the ends of these shelf -like plates project in a pectination along the 

 side of the abdomen. 



Ctenerpeton alveolatum Cope. 



CoPB, Proc. Am. Phil. Soc., xxxvi, p. 83, pi. iii, fig. i, 1897. 

 MooDlE, Proc. U. S. Nat. lilus., 37, p. 24, pi. 10, 1909. 



Type: Specimen No. 4475, U. S. National Museum, Lacoe Collection. 



Horizon and locality : Linton, Ohio, Coal Measures. 



The species rests on a single specimen (plate 19) from Linton, Ohio, and is pre- 

 served on a block of bituminous coal. It is in a very good state of preservation. 

 There are present on the block of coal a part of the right fore limb, the greater part 

 of the dorsal portion of the animal, and the anterior part of the tail. There are no 

 evidences of hind limbs, although this may not be taken as evidence that they were 

 not present on the animal. No thoracic plates have been observed. The chevron 

 armature is present beyond the cloacal region, but there are no evidences of the 

 specialized clasping organs which are apparently developed from the abdominal 

 armature in some forms (251). 



Each dermosseous rod of the abdominal scutellation consists of three pieces — 

 a median angulated portion and the two lateral parts which form the shelf-like 

 projection along the side of the abdomen (plate 23, fig. 2). The marginal chevron 

 differs in form from the other plate, aside from the fact that it is not angulated. 

 The lateral shelf is composed of flattened plates which articulate with the median 

 piece, and at the place of articulation there is a ridge present in the .specimen. The ex- 

 terior plates are curved backwards and are somewhat attenuated distally. They are 

 broader than the median piece and differ also in the absence of the characteristic 

 alveoli. The median plate is angulated and is of more slender proportions than the lat- 

 eral pieces. Its ventral sixrface is ornamented with a single row of closely placed 



