﻿THE CARBONIFEROUS AND DEVONIAN FORMATIONS. 165 



Apedodus priscus, Leidy. 



This species is founded upon specimens of a tooth and a fragment of bone, from the 

 Old Red Sandstone Formation of Columbia County, Pennsylvania, which were sent 

 for my inspection by Prof. Baird, from the cabinet of the Smithsonian Institution. 



The tooth is seven lines in length, compressed conical, with trenchant edges, and is 

 slightly curved. The two broad sides are very nearly symmetrical; the transverse 

 section being elliptical and rather abruptly narrowed towards the acute poles. The 

 trenchant margins are entire, and the surfaces are smooth, except at their lower half, 

 where the tooth is grooved as in Lepiclosteus and Holoptychius. The base of the tooth 

 is four lines and a quarter in breadth, and two lines and a half in thickness. The 

 tooth appears to be solid, and is invested with thin enamel. 



The fragment of bone mentioned, which I have considered as having belonged to 

 the same fish as the tooth, for no other reason than that they were found in association, 

 appears to be a portion of an opercular, or perhaps a sub-opercular bone. It is thick 

 and dense, and on the exposed surface is invested with thin, shining, and minutely 

 granulated enamel. Viewing the specimen as an opercular bone, it has been over two 

 inches in length, and about an inch and a half at its widest part. Its anterior margin 

 is thin, and beveled off for the fourth of an inch for adaptation to the preopercular 

 bone. The posterior margin is convex ; the lower extremity is a little prolonged ; 

 and the upper broken margin of the specimen reaches one line in thickness. 



Plate 17, fig. 5. — Tooth of Apedodus priscus. 



fig. 6. — Transverse section of the same tooth, 

 fig. 7. — Portion of an opercular bone. 



