26 PROCEEDINGS OF THE NATIONAL MUSEUM vvl. G8 



BRYANTODUS TENUIS, new species 



Plato 10, fig. 7 



This differs from all other species of the genus in the narrowness 

 of the bar and the minute denticles which are closely arranged on 

 one half and farther apart on the other. The main cusp is dis- 

 tinguishable but not conspicuous^ different from the separated 

 denticles. 



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

 Tenn. 



noIof!/pe.— Cat. No. 11025 U.S.N.M. 



BKYANTODUS TRANSITANS, new species 



Plate 4, figs. 10, 11 



This species has a general resemblance in the curvature of the bar, 

 and size and arrangement of the denticles to Prioniodella aeqiudens 

 but it is readily distinguished by the development of one of the 

 median denticles as a main cusp with flattened edges, which fuse 

 somewhat with neighboring denticles. 



Occiu^cnce. — Devonian (Rhinestreet) : Shaleton, N. Y. 



Gotype.— Cat. No. 11262, U.S.N.M. 



BRYANTODUS CURVATUS, new species 



Plate 4, figs. 19, 20 



This species is intermediate in its characters between Prioniodina 

 and Bryantodiis., the complete separation of the denticles being as in 

 the former and the sharp lateral edges of the main cusp as in the 

 latter. It may be viewed as a further step in the transition between 

 the two genera from that seen in Bryantodus semisefaratus in which 

 fusion of the posterior denticles still occurs. Prioniodina suhcurvata 

 has a similar form but has a rounded main cusp. 



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



Cotype.— Cat. No. 11271, U.S.N.M. 



BRYANTODUS SUBRADIATUS, new species 



Plate 10, figs. 12, 13 



Similar to B. radiatus Hinde, 1879, from the Genesee shale of 

 western New York but differs in the much smaller size of the main 

 cusp, in the more uniform size of the denticles and in lacking the 

 protuberance beneath the main cusp. 



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

 Tenn. 



Voty pes.— Cat. No. 11022, U.S.N.M. 



