FISHES OF THE CARBONIFEROUS SYSTEM. 89 
give any satisfactory generic definitions to these different groups. In time 
more material will doubtless make easy what-is now impossible. 
The teeth here described as new species of Dipterus are chiefly from a 
bone bed in the Chemung conglomerate in northwestern Pennsylvania. In 
this conglomerate nothing is well preserved but the dense palate teeth of 
these fishes, and even these are sometimes rolled into rounded pebbles; yet 
we occasionally find ganoid scales and those that probably clothed the 
fishes to which the teeth appertained. In this formation, generally classed 
as Upper Devonian, but in my judgment more properly considered as the 
base of the Carboniferous, a careful search will undoubtedly bring to light 
a large number of fish remains which cannot fail to be of great interest. 
What we know of them now is almost solely due to the efforts of Mr. F. A. 
Randall and Mr. C. E. Beecher, who, while much occupied with business 
duties, found time to observe and collect with discrimination and success. 
It will be noticed that a very important addition has been made to the 
list of Dipterine fishes before known by the discovery by Mr. Frank Wagner 
of a magnificent species of Ctenodus in the Cleveland shale (Lower Carbonif- 
erous) at Cleveland, Ohio. This tooth, which is fairly shown in Pl. XX VII, 
Fig. 30, has been named C. Wagneri, in recognition of the sharp-eyed indus- 
try of Mr. Wagner, who has obtained from this formation and locality, before 
considered barren, an interesting series of fish remains. 
Diprerus (CTENopuS) NELSONT, n. sp. 
Plate XX VII, Figs. 19, 20. 
Teeth ovoid or triangular in outline, one inch to one inch seven lines 
long, one-half inch to one inch in width; crown marked with seven strong, 
acute, radiating ridges, somewhat waved or obscurely tuberculated. The 
anterior margin is formed by the strongest of these ridges, the others dimin- 
ishing in size posteriorly. Though usually seven in number, the rudiment 
of an eighth is sometimes seen at the back end. 
The teeth of this species will be at once distinguished from all others 
described by their strong subacute ridges, of which the edges are highly 
polished; sometimes quite plain, especially in large and old teeth; in those 
