l6o NEW YORK STATE MUSEUM 



this genus, or referred to Sagenodus, Ctenodus, and others having a similar 

 form of dentition. Recent discoveries having brought to light large num- 

 bers of Dipterine teeth from the western Devonic, the leading species 

 which are here figured and described offer valuable points of comparison 

 with those from the eastern States. 



Dipterus uddeni P^astman 



Plate 4, figures 3, 4 



1899 Dipterus uddeni J. A. UdJcii. Jour. Geol. 7: 494 (name only) 



1900 1 ) i p t e r u s uddeni C. R. Eastman. Jour. Geol. 8: 37, text fig. 5 



This species, the earliest to make its appearance in the Devonic rocks 

 of this country, is founded upon a unique lower dental plate from the base 

 of the Cedar V^alley limestone (Erian) near New Buffalo, la. The specific 

 title is bestowed in honor of its discoverer. Professor J. A. Udden, formerly 

 of the Iowa State Geological Survey. It has a total length of 36 mm, is 

 moderately convex, and remarkable for the paucity of its denticulated 

 ridges. These are but four in number, and radiate outwards from the pos- 

 terior 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, jof large 

 size, and well separated. There is a gradual increase in size of all the 

 denticles from within the inner margin outwards. The coronal surface is 

 finely punctate. 



Formation and locality. Base of the Cedar Valley limestone ; New 



Buffalo, la. 



Dipterus calvini Eastman 



Plate 4, figure i 



1900 Dipterus calvini C. R. Eastman. Jour. Geol. 8: 38, text fig. 7 

 Lower dental plate elliptical in outline, and moderately convex in an 

 anteroposterior direction. Eight tuberculated ridges extend from the outer 

 margin to about the middle of the plate, the two anterior ones larger than 

 the rest and elevated into a slight fold. Coronal surface considerably worn 

 in the type specimen, and external margin partially broken. Tubercles 



