10 PROCEEDINGS OF THE NATIONAL MUSEUM vol.68 



PRIONIODUS CONCAVUS, new species 



Plate 9, fig. 11 



Probably closely allied to P. proclinis in its denticles but with 

 a more concave base. The terminal denticle is relatively stronger 

 and the smaller denticles are more closely arranged. 



Occurrence. — Mississippian (Hardin sandstone) : Momit Pleasant, 

 Tenn. 



H olotype.— C2ii. No. 11036, U.S.N.M. 



PRIONIODUS REVERSUS, new species 



Plate 9, fig. 4 



Similar to P. parvidentatus but attitude of denticles and terminal 

 cusp reversed in that the}^ incline backward instead of forward. 



Occurrence. — Mississippian (Hardin sandstone) : Mount Pleasant, 

 Tenn. 



Holoh/pe.— Cat. No. 11037 U.S.N.M. 



PRIONIODUS DISPARILIS, new species 

 Plate 9, fig. 12 



In this species the terminal cusp leans forward, is very large, 

 sharp edged with a blunt tip and a rather short downward projec- 

 tion. The bar is nearly straight, slender, slowly tapering, and its 

 upper edge completely occupied by closely arranged, rather short 

 more or less fused denticles nearly at right angles to it. 



Occurrence. — Mississippian (Hardin sandstone) : Mount Pleasant, 

 Tenn. 



Holotype.— Cat. No. 11030, U.S.N.M. 



PRIONIODUS INEQUALIS. new species 

 Plate 9, fig. 6 



Founded upon a single specimen characterized by a very long 

 straight terminal cusp strongly inclining forward with short down- 

 ward projection and short bar with two strong denticles vertical and 

 thus diverging strongly from the main cusp. Bar short possibly in- 

 complete. 



Occurrence. — Mississippian (Hardin sandstone) : Mount Pleasant, 

 Tenn. 



Holotype.— Cat. No. 11034, U.S.N.M. 



PRIONIODUS PROCLINATUS. new species 



Plate 1, fig. 22 



Distinguished from its nearest allies by the great size, straightness 

 and strong anterior inclination of the terminal cusp. The lateral 



