Plate XI— Continued. 



PAGE. 



Fig. 20-23. . Tanaodus sculptus, St. J. and W 373 



20 a. Concave face of large symmetrical tooth; 20 b, convex face, coronal folds obsolete; 



20 c, profile section. St. Lonis limestone ; Alton, Illinois. 



21 a. Outline of concave face of small eccentric tooth; 21 6, the same enlarged two diam- 



eters; 21 c, convex face; 21 d, profile section. St. Lonis beds ; Pella, Iowa. 



22 a, b, c. Similar views of small symmetrical tooth. Same horizon and locality. 



23 a. Outline of concave face; 23 b, view of concave face, enlarged two diameters; 23 c, con- 



vex face, showing coronal folds; 23 d, profile section, showiDg outline of perfect 

 root, and unusual concavity of the concave face. St. Louis ; Alton, Illinois. 



Fig- 26. Tanaodus ghosstpucatus, St. J. and W 375 



26 a. Concave face of tooth, partially restored in outline ; 26 b, convex face j 26 c, profile sec- 



tion. Chester limestone ; Chester, Illinois. 

 Fig. 27. Taxaodus subluxatus, St. J. and "W 368 



27 a. Outline of convex aspect, partially restored, enlarged two diameters; 27 6, profile sec- 



tion. St. Louis limestone ; Alton, Illinois. 



Fig. 28. Axtliodus perovaus, St. J. and ~W 393 



28 a. Concave face, basal border imperfect j 28 b, convex face ; 28 c, profile section. "Warsaw 



beds. 



Fig. 29. Axtliodus gracilis, St. J. and W 393 



29 a. View of concave crown-face, basal border broken away ; 29 6, convex face ; 29 c, profile 



section. "Warsaw beds. 



