PLATE VI 



PAGE. 



Fig. 1-3. Orodus fastigiatus, St. J. and TV 306 



1 a. Posterior face of large tooth ; 1 b, view of outer face ; 1 c, outline of crown from above ; 



1 d, profile section. Upper Burlington limestone; Louisa county, Iowa. 



2 a, b, c, d. Similar views of smaller specimen. Same horizon and locality. 



3 a. View of posterior face of tooth, showing crown worn down to a regular arched out- 



line; 3 6, view from above. Same horizon and locality. 



Fig. 4,5. Orodus turgtdus, St. J. and TV 310 



4 a Posterior face of tooth, enlarged four diameters ; 4 b, outer face ; 4 c, outline of crown 



from above, enlarged two diameters; 4 d, profile section. Chester limestone; 

 Chester, Illinois. 



5 a, Outline of posterior face of a more slender tooth, enlarged two diameters. Same hori- 



zon and locality. 



Fig. 6. Orodus parvulus, St. J and W 309 



6 a View of posterior face of tooth, enlarged two diameters ; 6 b, outer face ; 6 c, outline 



of crown from above; 6 d, profile section. St. Louis limestone; Alton, Illinois. 



Fig. 7,8. Orodus Djedaleus, St. J. and TV 301 



7 a. Posterior face of large size tooth; 7 &, outer face; 7 o, view of crown from above; 7 d t 



profile section. Kinderhook beds ; Burlington, Iowa. 



8 a. View from above of a slightly smaller, arcuate tooth; 8 &, outer face. Same horizon 



and locality. 



Fig. 9. Mesodmodus exsculptus, St. J. and TV 291 



9 a, b, c. Views of the posterior face, crown from above, and profile section of a large tooth ; 



9 d, outline from above of another specimen. Kinderhook beds; Burlington, 

 Iowa 



Fig. 10-15. Ouoi'is decussatus, St. J. and TV 300 



10 a. View of medium sized tooth from above; 10 b, outline view of inner face; 10 c, profile 



section. Kinderhook beds ; Burlington, Iowa. 

 11a. View of posterior face of large, perfect tooth; 11 b, opposite face ; 11 c, profile section ; 



U d, outline, from above. Same horizon and locality. 



12 a. Posterior face of large worn tooth ; 12 b, outer face. Same horizon aDd locality. 



13 a, b, c. Similar views of a tooth, cone truncated from wear. Same horizon and locality. 



14 a. View from above of a tooth of uniform proportions, also worn by attrition. Same 



horizon and locality. 



15 a. View of a small tooth from above. Same hurizon and locality. 



Fig. 10-18. Agassizodus scitulus, St. J. and TV 322 



16 a. Outer face of tooth, enlarged three diameters; 16 &, posterior face; 16 c, crown from 



above ; 16 d, profile section, Middle Coal Measures ; Iowa. 



17 a. Group of three teeth, nat. size, showing both faces. Middle Coal Measures; Iowa. 



18 a. View of outer face of more robust tooth ; 18 b, crown from above ; 18 c, profile section. 



Coal JS T o. 5 ; Illinois. 



Fig. 19-24. Psepiiodus 1 eeticui.atus, St. J. and TV 417 



19 a. Posterior face of very large tooth ; 19 &, outer face, showing inferior surface of base ; 



19 c, outline of crown from above; 19 d, profile section. Kinderhook beds ; Bur- 

 lington, Iowa. 



20 a. Inner face of mediuni-sizo tooth; 20 &, opposite face ; 20 c, profile section. Same hori- 



zon and locality. 



21 a,b,c. Similar views of smaller specimen, the reticulated ornamentation more restricted 



to the basal border. Same horizon and locality. 



22 a. View of crown from above, of a worn tooth, showing no trace of ornamentation. Same 



horizon and locality. 



23 a, b, c, d. Views of the posterior and outer faces, outline from above, and profile section of 



a small tooth. Same horizon and locality. 



24 a, b. Posterior and outer views of a small, acuminate tooth; 2-1 c, profile outline; 24 d, 



outline of crown from above. Same horizon and locality. 



Fig. 25. Orodus TVhitei, St. J. and W 297 



25 a. View of a scries of seven teeth from above ; 25 b, inner margin of the series, showing 



posterior face of the iuuer tooth ; 25 c, outline view as seen from the straight or 

 anterior bonier of the series; 25 d, view from the postcro-outer side, showing 

 the deltoid figure and inrolimeut of the series. Kinderhook beds; Marshall 

 county, Iowa. 



Fig. 26. Orodus seglectus, St. J. and TV 308 



26 a. View of posterior face of medium-sized tooth; 26 &, outer face; 26 c, d, outline of 



crown from above, and profile section. St. Louis limestone; Pella, Iowa. 



