14 THE GENESEE CONODONTS 
The form, character and microscopic structure of these teeth 
are such as to recall somewhat the description and figures given 
by Pander of Prioniodus tulensis, a species hitherto recorded 
only from Russia. Prioniodus recedens, however, differs from 
Prioniodus tulensis in its more robust proportion, its less acute, 
tapering and recurved laniary tooth, its less sigmoidal profile, 

Fig. 4. Prioniodus tulensis, showing minute structure. After Pander. 
and in its subsidiary denticles, which are blunt and obtusely 
rounded. ‘The base, too, is less compressed. It is clear, as above 
explained, that the number of subsidiary denticles is not a 
reliable character in defining species. I reproduce here (fig. 4) 
two of Pander’s figures which show well the microscopic struc- 
ture which obtains throughout the genus. The cavity under the 
main cusp in those examples which have an elongated base, is 
continued as a narrow, shallow and polished groove. 
PRIONIODUS ABBREVIATUS, HINDE? 
Plate 1. figs, 3-9; Plate lliatie. 7 
1879. Prioniodus abbreviatus, G. J. Hinde, Quar. Jour. Geol. Soc., 
Vol. XXXV, p. 359: Plate XV, fig. 15. 
Dr. Hinde’s description of this species, which he collected 
from the Conodont bed of Eighteen Mile Creek, is as follows: 
“Base of tooth very short and stout, at one end a comparatively 
*As Hinde’s Paper is not always to be found in libraries, it may be 
remarked that rather poor copies of all his figures, together with 
brief descriptions, may be found in Prof. Grabau’s work on the Geology 
and Palaeontology of Eighteen Mile Creek, Bull. Buffalo Soc. Nat. 
Sciences, Vol. VI, Part 2. 
