142 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



thirds of the mandible is narrow wedge-shaped ; the external surface is coarsely 

 pitted. There are no teeth preserved. The pectoral elements are displaced, but the 

 clavicles are subtriangular, and are strongly ridged toward the inner margin. The 

 interclavicle is short spatulate, the narrow portion directed anteriorly ; the posterior 

 rounded. It is coarsely pitted medially, and coarsely and strongly radiate-ridged to 

 the margin. The abdominal armature commences immediately behind the pectoral 

 girdle. It consists of elongate, narrow, subcylindric scales, which meet on the 

 median line, converging anteriorly. Small limbs are present. 



Measurements of Ptyonius marshii Cope. 



Type specimen: mm. 



Length of fragmentary skull 7 



Width of skull as preserved 5 



Length of entire specimen 68 



Width across pectoral plates 8 



Width across belly 7 



Specimen No. 1098 G, American Museum: 



Length of specimen 32 



Width of specimen 7 



4 scutes of abdominal armature in i mm. 



Ptyonius nummifer Cope. 



Cope, Geol. Surv. Ohio, 11, pt. 11, pp. 374, 375, pi. xli, figs. 2 and 3, 1875. 

 MooDiE, Bull. Am. Mus. Nat. Hist., xxvi, p. 356, pi. 63, fig. 3, 1909. 



Type : Specimen No. 8546 G, American Museum of Natural History. No. 

 8614 G, same museum, is associated with the type specimen. 



Horizon and locality : Linton, Ohio, Coal Measures. 



Two well-preserved individuals display peculiarities which indicate specific dis- 

 tinctness from the previously known species of Ptyonius. The abdominal rods are 

 of the coarse type of those of P. marshii. The caudal fans are well developed, and 

 not so wide as in P. pectinatus. The interclavicle is a discoid body of different form 

 from that of P. marshii and I can not detect the clavicles. The sculpture consists 

 of strong ridges, which radiate from the center to near the border. Immediately in 

 front of this interclavicle is the head, which has a different form from that of the 

 other known species. The interorbital width is two-thirds the long diameter of the 

 orbit. The structure of the skull can not be made out. A slender, elongate hind 

 limb is present in the second specimen, and a humerus is well preserved in the type. 



Measurements of the Type of Ptyonius nummifer Cope. 

 (No. 8546 G, American Museum of Natural History. No. 8614 G is associated in the same species.) 



tnm. mm. 



Length to beginning of caudal fans 65 Width of abdominal armature 8 



Length of head IS Length of a caudal fan 2.5 



Length from muzzle to orbits 6 I^ength of femur 5 



Length of interclavicle 7 Proximal width of femur i .5 



Width of interclavicle 8 



Ptyonius serrula Cope. 



Cope, Proc. Am. Phil. Soc., 1871, p. 177. 



Cope, Geol. Surv. Ohio, 11, pt. n, p. 379, pi. xxviii, fig. 5; pi. xxx, fig. I, 1875. , 



Type: Specimen No. 8615 G, American Museum of Natural History. 

 Horizon and locality: Linton, Ohio, Coal Measures. 



The specimens of this species indicate that the form was only about half the size 

 of Ptyonius pectinatus. The interclavicle is narrower and more reticulately sculp- 



