PLATE XIII. 



PAGE. 

 Fig. 1,2. Fissodus bifidus, St. J. and W 414 



1 a. Concave face of perfect tooth -, 1 &, convex face: 1 c, profile section. Chester lime- 



stone; Chester, Illinois. 



2 a. Concave fa<:e of smaller, less perfect specimen ; 2 t>, profile section. Same horizon and 



locality. 

 Fig. 3. Fissodus tricuspidatus, St. J. and "W 415 



3 a. Concave face of an imperfect t;oih; basal borders restored; 3 6, opposite lace $ 3 c, 



profile section. Chester. Illinois. 

 Fig. 4,5. Cholodus ix.equaus, St. J. and W 416 



4 a. Concave face of an imperfect tooth, basal border broken away ; 4 b, view of convex 



face ; 4 c, profile section. Upper Coal Measures ; Iowa. 



5 a. Yiew of concave face of more robust tooth, basal border and root destroyed; 5 b, con- 



vex face ; 5 c, profile section. Upper Coal Measures : Springfield, Illinois. 

 Fig. 6,7. Peltodus quadratus, St. J. and \V 410 



6 a. Convex face of perfect tooth, enlarged two diameters; 6 b, profile section. St. Louis 



limestone: Alton, Illinois. 



7 a. Concave face of au imperfect tooth; 7 b, convex face ; 7 c, profile section. Same hori- 



zon and locality. 



Fig. 8. Peltodus trans versus, St. J. and W 412 



8 a. Convex face of nearly entire tooth, enlarged two diameters ; 8 6. profile section. Coal 



Measures ; CarlinviUe, Illinois. 



Fig 9. Pei.todus ? pnccmrriAT/us, St. J. and W 411 



9 a. Concave face, basal margin imperfect ; 9 b, convex face, root restored in outline ; 9 c, 



profile section. Chester limestone ; Chester, Illinois. 



Fig. 10. Polyrhizodus carboxarius, St. J. and TV 389 



10 a. Appearance of original example, convex face, partially restored in outline ; 10 &, profile 



section. Upper Coal Measures ; LaSalle, IUinois- 

 Fig. 11. Polvuhizodus "WiLLLAMsi, St. J. and TV 384 



11 a. View of concave face, showing dentate root; 11 &, view of crown from above, showing 



triturating surface in the convex face ; 11 c. profile section. Keokuk limestone ; 

 Boonville, Missouri. 



Fig. 12. Poi.YKinzoDus Piasaensjs, St. J, and TV 386 



12 a. Concave face of nearly perfect tooth ; 12 b, convex face; 12c, profile section. "Warsaw 



beds; above Alton. Illinois. 



Fig. 13. Polyrhizodus amplus. St. J. and TV 387 



13 a. Concave face of perfect tooth, 13 b, convex face: 13 c, profile section. St. Louis lime- 



stone: Alton, Illinois. 



Fig. 14. Pni-YKHIZODUS LlTTONl, ^. and W 385 



14 a, b, c. Concave and convex faces, and profile section, of nearly perfect tooth, introduced 



for comparison with preceding form. St. Louis ; Alton, Illinois. 

 Fig. 15. POLYKHizoDUS XAXUs, St. J. and W.... 386 



15 a, b. Convex face and profile section ; 15 c, rf, the same views, enlarged two diameters. 



Keokuk limestone j Beutonsport. Iowa. 



Fig. 16. Dactylodus excavatus, St. J. and TV 392 



16 a. Concave face, root broken away, enlarged two diameters: 16 b, convex face; 16 c, pro- 



file section. Chester limestone ; Chester, Illinois. 

 Fig. 17, 18. Dactylodus coxcayis, St. J. and TV 390 



17 a. Concave face of medium-size tooth ; 17 b, convex face ; 17 c. profile section. St. Louis 



limestone; Alton, Illinois. 



18 a. Concave face of large specimen, extremities of fangs broken away ; 18 &, convex face ; 



IS c, profile section. Same horizon and locality. 



Fig. 19. Dactylodus minimus, St. J. and TV 391 



19 a. Concave face of tooth, enlarged two diameters ; 19 6, opposite face ; 19 c, profile section. 



St. Louis limestone ; Alton, Illinois. 



