DEVONIC FISHES OF THE NEW YORK FORMATIONS 1 69 



with fine tuberculations, more or less conical, and radiately grooved. The 

 clavicle is triangular in shape, with relatively large inferior limb ; and the 

 infraclavicle is without an elongated ascending process. In this species, 

 also, the presymphysial bone is very prominent, its teeth being much larger 

 than those of the dentary. Remains of O. sigmoides are not uncom- 

 mon in the Columbus and Delaware limestones of Ohio, and probably occur 

 also in the Onondaga limestone of Leroy, N. Y. A few detached presym- 

 physial teeth comparable in a general way to this species are also known 

 from the Hamilton of Milwaukee, Wis., one such being figured in plate i, 

 figure 3 ; others, with less pronounced sigmoidal curvature, are present in 

 the Middle Devonic of the Eifel district. As an example of the latter a 

 single tooth belonging to the Cambridge Museum is represented alongside 

 of the Hamilton form in the same plate for comparison. 



By far the most abundant of any species of this genus is that which 

 Newberry described under the name of O. h o p k i n s i, occurring typically 

 in the Chemung of Delaware county, N. Y., but being also represented in 

 enormous quantities in the basal bituminous layer of the Marcellus shale of 

 the same State. The teeth are not satisfactorily distinguished from those 

 of the type species, but are of prevailingly smaller size, and somewhat lesser 

 curvature. The average length is stated by Newberry to be about i inch. 

 This, together with the considerable stratigraphic interval separating them 

 from O. sigmoides, probably furnishes sufficient reason for their main- 

 tenance as distinct species. A series of five well preserved presymphysial 

 teeth belonging to this species, from the Chemung of Franklin, N. Y. is 

 shown in plate 3, figure 3. 



An undetermined species of Onychodus seems to be indicated by a 

 few detached plates and other fragments from the Cedar Valley limestone 

 (Mesodevonic) of Iowa, and Hamilton of Oran, Onondaga county, N. Y. 

 A single detached scale from the latter locality, with characters indistin- 

 guishable from those of the type species, is shown in plate 3, figure 2. 

 Scales displaying a Coelacanthuslike ornamentation, but generically indeter- 

 minate, occur also in the Portage beds of Livingston county, New York. 



