DEFINITION OF THE ORDER SALIENTIA, LAURENTI, 1768. 73 



forearm may be united as in the frogs, and the length and curvature of the femur are seen 

 among these animals rather than the Salamanders. The form of the femur is different from 

 that of Amphibamus grandiceps Cope, which also differs in the presence of dermal scales 

 and ventral scutellag." (123.) 



Pelion lyelli Wyman. 



WYMAN, Am. Jour. Sci. (2), xxy, p. 160, 1858. 



COPE, Proc. Acad. Nat. Sci. Phil., 1868, p. 211. 



('uric, Geol. Surv. Ohio, n, pt. II, p. 390, pi. xxvi, fig. I, 1875. 



MOODIE, Pop. Sci. Monthly, i.xxu, p. 562, fig. i, 1908. 



Type: Specimen No. 7909 G, American Museum of Natural History. 



Horizon and locality: Linton, Ohio, Coal Measures. (Plate 24, fig. i.) 



This was the first species described from the Linton, Ohio, deposits. It was made 

 known by Dr. Wyman in 1857 at the meeting of the American Association for the 

 Advancement of Science for that year. The species was subsequently studied by Cope. 

 He merely confirmed Wyman's observations. The following description is based on 

 the descriptions of Cope and Wyman and on my own study of the type specimen. 



This is the most frog-like, in appearance at least, of all the Amphibia which 

 have so far been discovered in the Carboniferous. The skull especially has a shape 

 which is strikingly frog-like, and the long hind limbs lend further likeness to the 

 tailless forms. Pelion may have been a jumping creature, if we may judge from its 

 long hind legs. Wyman and Cope have both called attention to the frog-like appear- 

 ance of the specimen, and this is apparent at the first glance. It is probable that 

 the resemblance has some significance as to the ancestry of the Salientia, and it 

 may indicate the first step in the origin of the tailless Amphibia. It is possible that 

 the frogs began to be separated from the other Amphibia during the Carboniferous. 

 The first frogs we know are from the Jurassic, where they are well-developed 

 ranids. If Pelion be a frog ancestor, then the history of the group from the Coal 

 Measures to Jurassic is an unknown story. 



The specimen is preserved on its back and it is thus impossible to tell as to the 

 structure of the skull. Cope was of the opinion that the depressed areas on the 

 sides of the elongate parasphenoid were the orbits, and if so the resemblance to the 

 frogs is much more striking. In the frogs there is a strong process from the ptery- 

 goid which projects inward to meet a corresponding process from the parasphenoid. 

 This forms a heavy rod behind the palatine vacuity. There is a heavy rod repre- 

 sented in the specimen and a part of it is certainly the external process of the para- 

 sphenoid, but whether it is to be interpreted as in the frog is an open question. The 

 outline of the cranium is partially obscured by the mandibles, but the anterior part 

 is represented by a raised line, as shown in figure 17. In the anterior part of this 

 space there are two ridges which may be tooth ridges. If they are teeth there is a 

 great similarity to the premaxillary and vomerine teeth of Necturus, since the 

 ridges are widely separated at the median line and approximated distally, as they 

 are in Necturus. The mandible is preserved entire and its form is strikingly frog- 

 like. Its posterior angles project over the quadrate area and seem to have had an 

 upturned projection such as is found in the mandibles of the Crocodilia. 



There are impressions of 20 vertebrae preserved, and they cover a little more 

 than half of the presacral region. There may have been 28 to 30 presacrals. The 



