24 PEOCEEDINGS OF THE NATIONAL MUSEUM vol, 72 



DESCRIPTION OF EARLY MISSISSIPPIAN SPECIES 



All of the species herein described were obtained in the Chatta- 

 nooga black shale of Early Mississippian age at a locality 13 miles 

 east of north of Huntsville, Ala. 



Family PRIONIODIDAE Ulrich and Bassler, 1926 



Genus PRIONIODUS (Hinde) Bryant, 1921 



PRIONIODUS ALABAMENSIS, new species 



Plate 9, figs. 1, 2 



Tooth consisting of a long, thin, tapering, recurved cusp rising 

 from a flat, thick bar. This central cusp is not produced below the 

 base. A series of short, sharp pointed denticles which are well 

 separated, rises at an acute angle from the bar. 



G oty pes.— C2it No. 11431, U.S.N.M. 



PRIONIODUS ALATOIDES, new species 



Plate 9, fig. 3 



This is a more delicate species than Hinde's Prioniodus alatus. 

 The bar is straight, flat, and thin. The cusp is very wide at the base 

 but tapers to a sharp point, extends below and forms an obtuse angle 

 with the bar. The denticles and the cusp rise from the bar at obtuse 

 angles. 



Holotype.—C^t. No. 11432, U.S.N.M. 



PRIONIODUS CULTRATUS Ulrich and Bassler, 1926 



Plate 9, fig. 4 



1926. Prioniodus cultratus Uleich and Bassler, Proc. U. S. Nat. Mus., vol. 68^ 

 art. 12, p. 9, pi. 9, fig. 7. 



Tooth composed of a broad, flat, tapering cusp rising from the 

 slightly deflected end of a moderately flat bar at a right angle. 

 Four long, sharp pointed, slightly recurved denticles are placed on 

 the bar at obtuse angles with the base of the cusp. These are suc- 

 ceeded by several short, smaller denticles. 



Plesiotype.— Cat No. 11433, U.S.N.M. 



Genus LIGONODINA Ulrich and Bassler, 1926 



LIGONODINA PARVULA, new spccicB 



Plate 9, fig. 5 



The pointed, recurved cusp extends below a slightly curved bar on 

 which are several denticles, well rounded and set at obtuse angles to 



