﻿392 CEOSSOPTEHTGn. 



Genus ONYCHODUS, Newberry. 

 [Bull. National Institute, 1857, p. 5.] 

 External bones and scales ornamented with tuberculations, more 

 or less conical and radiately grooved. Clavicle triangular in shape, 

 with relatively large inferior limb ; infraclavicle without an elon- 

 gated ascending process. Presymphysial bone very prominent, its 

 teeth much larger than thoso of the dentary. 



Onychodus sigmoides, Newberry. 



1857. Onychodus sigmoides, J. S. Newberry, Bull. National Inst. p. 5. 

 1862. Onychodus hopkinsi, J. S. Newberry {errore), Amer. Journ. Sci. 



[2] vol. xxxiv. p. 77, woodc. fig. 3. 

 1873. Onychodus sigmoides, J. S. Newberry, Rep. Geol. Surv. Ohio, 



vol. i. pt. ii. p. 299, pi. xxvi. figs. 1-5, pi. xxvii. figs. 1, 2. 

 1889. Onychodus sigmoides, J. S. Newberry, Palseoz. Fishes N. America 



(Mon. U.S. Geol. Surv. no. xvi.), p. 56, pi. xxxvi. figs. 1-4, 



pi. xxxvii. figs. 1-10. 



Type. Portions of mandible ; Columbia College, New York. 



The type species of large size, the longest presymphysial teeth 

 measuring 0*058 in length. Tuberculations upon scales conical and 

 prominently sculptured, those upon the external bones rounder, 

 somewhat smoother, and more numerous. Dentary teeth regular 

 in size and shape throughout the greater part of the thickened oral 

 border, each tumid in its basal half and tapering to the very slender 

 enamelled apical portion ; presymphysial teeth sigmoidally curved, 

 stout, with a large central cavity, nearly regular in size, and loosely 

 attached to the supporting bone. 



Several detached bones of this species, in the Museum of Colum- 

 bia College, New York, are figured by Newberry, op. cit., 1889. 



Form. Sf Log. Corniferous Limestone (Lower Devonian) : Ohio. 



Not represented in the Collection. 



Onychodus anglicus, A. S. Woodward. 



[Plate XY. fig. 1.] 



1888. Onychodus anglicus, A. S. Woodward, Geol. Mag. [3] vol. v. 

 p. 500, woodc. 



Type. Presymphysial bone ; Oxford Museum. 



A very small species, known only by the presymphysial bone, 

 which is remarkably in-rolled in the form of a scroll at its inferior 

 extremity. Presymphysial teeth tumid in the basal half, much 



