18 PBOCEEDINGS OF THE NATIONAL MUSEUM vol. «S 



PRIONIODINA, new genus 



Base of tooth more or less curved, crowned with numerous, sub- 

 parallel, rounded, discrete denticles all inclined in one direction, one 

 of which located in the median third, is considerably larger than the 

 others. 



Genotype. — Prioniodina subcurvata^ new species. 



Range. — Upper Devonian, Early Mississippian. 



To this new genus the following previously described species are 

 referred Prioniodus geminus Hinde, 1900, P. recedens Bryant, 1921 

 and P. volborthii Pander, 1856. 



PRIONIODINA SUBCURVATA. new species 



Plate 4, figs. 22, 23, 24 



Tooth consisting of a stronglj?^ curved bar surmounted by about 

 18 denticles, all of which are of subequal size and uniformly sepa- 

 rated except the fourth or fifth from the shorter end, regarded as the 

 main cusp, which occupies nearly the space of two others and pro- 

 jects to a moderate extent beyond their tips. 



Occurrence. — Devonian (Rhinestreet shale) : Shaleton, N. Y. 



Cotypes.— Cat. No. 11252, U.S.N.M. 



PRIONIODINA SEPARATA, new species 



Plate 4, figs. 17, 18 



Like P. subcurvata but the main cusp is more median in position 

 and relatively smaller, the denticles are more slender, less tapering, 

 and their bases more widely expanded. Moreover the bar is less 

 curved. 



Occurrence. — Devonian (Rhinestreet) : Shaleton, N. Y. 



Cotypes.—Cat. No. 11253, U.S.N.M. 



PRIONIODELLA, new genus 



Like Prioniodina except that the denticles are subequal, none be- 

 ing particularly larger than the other. 



One end of the bar supposed to be the posterior because of the 

 slant of the denticles, is commonly produced into a blunt process. 

 The denticles are always close, either discrete throughout or more or 

 less c'oalescent, agreeing in the latter feature with Bi^antodus. Tlie 

 lack of a readily distinguishable main cusp separates this genus from 

 both Prioniodina and Bryantodus. 



Genotype. — Prioniodella normalh, new species. 



Range. — Upper Devonian, Early Mississippian. 



In addition to the species here described, Gentrodus invalidus 

 Bryant apparently belongs to this genus. 



