PLATE 2 



Dipnoaii dental plate 



Page 164 



1 Dental plate of undescribed Dipterine genus, with obsolescent tuber- 



cular ridges. Natural size 

 Upper Devonic (State Quarry beds) ; Johnson county, la. 

 Original in Museum of Comparative Zoology, Cambridge, Mass. 

 Acanthaspis armata Newb. 



2 Supposed antero-ventrolateral plate with fixed spinous process ; orna- 



mentation indicating a young individual. Natural size 

 Columbus limestone ; Sandusky, O. 

 Original in Museum of Comparative Zoology, Cambridge, Mass. 



Undctcruiincd A rtJi rod ire 



Page 157 



3 Dorsomedian plate of undetermined Arthrodire. x 2 

 Hamilton limestone; Milwaukee, Wis. 



Original in private collection of E. E. Teller, Milwaukee, Wis. 



4 Detached dorsomedian plate comparable to that shown in figure 3, 



and from same horizon and localit)-. x 2 

 Original in private collection of E. E. Teller, Milwaukee, Wis. 

 Rhynchodus pertenuis Eastm. 



Page 6g 



5 Anterior portion of lower dental plate. Natural size 

 Chemung beds of Franklin, Delaware co., N. Y. 

 Original in New York State Museum. 



5a Cross-section of same taken along line of fracture, shown imme- 

 diately below 



Dinichthys pustulosus Eastm. 



(.V« plates 5 a.ul I.I 



6 Left posterior palato-pterygoid dental plate, or "shear tooth." Nat- 



ural size 

 Hamilton limestone; Milwaukee, Wis. 

 Original in private collection of E. E. Teller 



