300 PROCEEDINGS OF THE NATIONAL 3IU8EVM. 



Deltodus ocddentalis (Leidy), p. 260. 



Fig. 3. Dental plate, natural size. 



Mississippian (St. Louis limestone); near St. Louis, Missouri. 



Polyrhizodus concavus (St. John and Worthen), p. 257. 



4. Dental plate, natural size. 



Mississippain (St. Louis limestone); near St. Louis, Missouri. 



Dipterus angustus (Newberry), p. 247. 



5. Impression of dental plate, natural size. 



Devonian (Chemung); Bradford County, Pennsylvania. 



Chomatodus-type of tooth, p. 257. 



G. Associated with Polyrhizodus grandis. Natural size. 



Mississippian (St. Louis limestone); (?) near St. Louis, Missouri. 



Cladodus spinosus Newberry and Worthen, p. 254. 



7. Tooth, natural size. 



Dinichthys pustulosus Eastman, p. 248. 



8. Posterior process of dorsomedian plate, natural size. 

 Upper Devonian; Johnson County, Iowa. 



Plate 9. 



Elonichthys perpennatus Eastman, p. 275. 



Fig. 1. An incomplete example, natural size. 

 Pennsylvanian; Mazon Creek, Illinois. 



Cheirodiis orbicularis (Newberry and Worthen), p. 276. 



2. A fairly well-preserved specimen, natural size. 

 Pennsylvanian; Mazon Creek, Illinois. 



Elonichthys hypsilepis Hay, p. 274. 



3. A nearly complete specimen, X J. 

 Pennsylvanian; Mazon Creek, Illinois. 



Khadinichihys gracilis (Newberry and Worthen), p. 274. 



4. A well preserved small specimen, X J. 

 Pennsylvanian; Mazon Creek, Illinois. 



Coelacanthus elegans (?) Newberry, p. 271. 



Figs. 5, 6. Two distorted incomplete skeletons, X^. 

 Pennsylvanian; Mazon Creek, Illinois. 



Plate 10. 



Coelacanilms exiguus Eastman, p. 271. 



Fig. 1. A well-preserved example, x J. 



Pennsylvanian; Mazon Creek, Illinois. 



