DEVONIC FISHES OF THE NEW YORK FORMATIONS 1 63 



terus," but in the explanation of figures it is identified as a mandibular 

 dental plate. It agrees with the preceding species in having a coarse tuber- 

 culation and very few ridges, some of them indistinct. The tubercles them- 

 selves are stated to be "somewhat compressed laterally, rounded, smooth, 

 and blunt at the summit." 



Formation and locality. Catskill sandstone (Chautauquan) ; Tioga 

 county, Pennsylvania. 



CHEMUNG SPECIES OF DIPTERUS 



Precise determination of Dipterus teeth from the Chemung proper of 

 New York and Pennsylvania is a matter of some difficulty, owing to imper- 

 fection of type material upon which the various " species " are founded, 

 and an insufficient series of specimens for illustrating the range of variation 

 common to both sets of dental plates, upper and lower. In the case of 

 some species, the original descriptions undoubtedly require emendation, but 

 it would be hazardous to attempt this without having recourse to a larger 

 and better suite of material than is at present available amongst different 

 museums. This much, however, one feels warranted in concluding: that 

 very probably not more than two well marked types of Dipterine teeth 

 occur in the Chemung proper of the eastern region. These are D. fla- 

 belliformis and D. nelsoni Newberry, the latter including New- 

 berry's so called D. levis (founded on worn specimens), and possibly also 

 D. quadrat us and m i n u t u s. Of Dipterus nelsoni both pala- 

 tine and mandibular dental plates are known, a good example of the latter 

 being represented in plate 4, figures 13, 14. For the original description of 

 these forms, which we are willing to leave as they are for the present, one 

 may consult Newberry's monograph, pages 87-91. Whether the so called 

 Dipterus ithacensis, considered by Williams' as "showing some 

 relationship perhaps to Pterichthys," properly belongs in this category 

 can not be determined from the meager account given of it, unaccompanied 

 by illustrations. 



' Williams, H. S. Notes on some Fish-remains from the Upper Devonic of New York 

 State (Abstract). Am. Ass'n Adv. Sci. 30th meeting. Proc. 1882. p. 192. 



