FOSSIL PISHES. 51 



center into a conspicuous boss, from which the surface falls off with 

 several gentle undulations to either end. The enameled surface is 

 highly polished but finely punctate throughout ; on the posterior face of 

 the central tubercle are a few fine radiating carinations. The enamel 

 folds at the base of the crown form, on the posterior face, a relatively 

 broad but irregular band ; on the opposite face a more sharply-defined, 

 single raised line. The root is flattened, pitted, and beveled on its lower 

 edge. This variety is represented in Figs. 11-11 i. A second variety is 

 indicated by Figs. 11 c-11 f. This is 12 lines long and very much flat- 

 tened, the crown showing several rudimentary tubercles, of which the 

 most conspicuous is nearer one end of the tooth than the other. Still 

 another form is half the size of those already mentioned and more sym- 

 metrical, the central cone more prominent, the surface smoother, etc. 

 (Figs. 11 ^, 11 h). 



All these, with many other specimens, were found so associated together 

 that it cannot be doubted that they formed the dentition of a single indi- 

 vidual. Their diversity of form and size shows very plainly the liability 

 to multiply species when describing detached teeth. 



With these teeth are quantities of dermal tubercles, which doubtless 

 belonged to the same fish that bore the teeth. These tubercles are gene- 

 rally elongated and have the enameled surface strongly marked with 

 revolving ridges and furrows. In the same stratum and in immediate 

 proximity to these teeth, were found spines of two species of Ctenacan- 

 thus {Gt. formosus and Ct. furcioarina-l/us), and teeth of Cladodus Pat- 

 tersoni. "With one of these spines the teeth under consideration undoubt- 

 edly belong ; and as the Cladodus is a very small species, we may conclude 

 that Orodus and Gtenaoam,thus are only parts of the same genus. 



Formation and Locality : Black shale of Waverly Group, Sclotoville, Ohio, and Vance 

 burg, Ky. 



Oeodus eleg-antulus. N. and W. 



Plate LVIII. Figs. 12, 13 a. 



A small and very neat species of Orodus which occurs rarely in the 

 Cleveland shale at Bedford, Cuyahoga County, is so much like that 

 described by Mr. Worthen and myself in the Illinois Eeport, under the 

 above name, that I have regarded it as probably the same. Some of the 

 specimens found, like that now figured, have all the essential characteris- 

 tics of those from Illinois, except that they are less arched ; while other and 

 smaller teeth have sometimes the median cone somewhat pyramidal, and 



