DENTITION OF SOME DEVONIAN FISHES 37 
GENUS D/PTERUS, SEDGWICK AND MURCHISON 
There are two distributional centers for this genus in America, 
between which there was apparently no communication. In the 
eastern province, which includes the Chemung-Catskill of New 
Yorkand Pennsylvania, it is associated with forms common to the 
Upper Devonian of Canada and Europe. In the western province 
(Iowa and Illinois to Manitoba) it ranges from the base of the 
Hamilton to near the top of the Devonian and is accompanied 
by Ptyctodus and a number of Dipnoan forms peculiar to this 
region." Here are found no traces of Crossopterygians or Ostra- 
coderms; in fact the western Neodevonian fish-fuana is entirely 
distinct from the eastern, and represents a different migratory 
movement. 
The Chemung proper contains but two well-recognized 
species of Dipterus, D. flabelliformis and D. nelsoni, the latter 
including Newberry’s so-called D. devs (founded on worn speci- 
mens), and possibly D. quadratus and D. minutus. From the 
Catskill of Pennsylvania four species are known: D. sherwood, 
D. fleischert, D. angustus and D. contraversus (=D. radiatus N.). 
Several of these species are founded on imperfect material, and 
the original descriptions require emendation, To this list may 
now be added four new species from the Middle and Upper 
Devonian of Iowa, the types of which are preserved in the 
Museum of Comparative Zodlogy at Cambridge, Massachusetts. 
1. D. uddeni, sp. nov. (Fig. 5).—This species is established 
on a unique mandibular dental plate from the base of the Cedar 
Valley limestone (Middle Devonian) near New Buffalo, lowa. 
It has a total length of 36™™, is moderately convex, and remark- 
able for the paucity of its denticulated ridges. These are only 
four in number, and radiate in gently curved lines from the 
posterior angle, which is worn smooth by use. The anterior 
row of denticles and inner moiety of the remaining rows are 
also considerably worn; but in the outer moiety of these rows 
the denticles are acutely conical, of large size and well separated. 
* Ann. Rep. Iowa Geol. Surv., Vol. VII (1896), Pl. IV; zézd, Vol. IX (1898), p. 302 ; 
Jour. GEOL., Vol. VII (1899), p. 77. 
