Plate I. — Continued. 



Fig. 12. Onychodus sp. indes. Middle Devonian; Eifel Dis- 

 trict, Rhenish Prussia. Detached presymphysial tooth differing 

 from the typical American species in its less pronounced curva- 

 ture and more slender form. Cross-section of base of crown 

 shown at the right. Original in the Museum of Comparative 

 Zoology, Cambridge, Mass. x 3-4. Page 240 



Fig. 13. Diplodus priscus Eastm. Upper Devonian; Elm- 

 hurst, Illinois. Detached tooth, anterior face, x 4-1. Page. 104 



Fig. 14. Acantliaspis armata Newberry. Columbus limestone 

 (Middle Devonian) ; Sandusky, Ohio. Dermal plate with seg- 

 mented spinous process, the whole strictly homologous with the 

 so-called "shoulder-girdle of Ehamphodus, " as described by 0. 

 Jaekel from the Upper Devonian of Wildungen, Waldeck. An 

 external dermal ossification formerly supposed to be of Arthro- 

 diran nature, but now considered, in the light of Jaekel 's discov- 

 ery, to belong to Rhynchodus or some similar Palseozoic Chhnae- 

 roid. x 5-7. Page 145 



Fig. 15. Detached Thelodus-like shagreen granule, of the 

 same nature and from the same horizon and locality as those 

 shows in Figs. 7 and 8. x 5-1. Page 72 



Fig. 16. Diplodus striatus Eastm. Upper Devonian; Elm- 

 hurst, Illinois. Anterior and posterior face of a single large de- 

 tached cone, x 4-1. Page 105 



Fig. 17. Cladodus monroei Eastm. Hydraulic limestone 

 (Hamilton) ; Milwaukee, Wisconsin. Detached tooth, coronal 

 apex and portion of the base broken away, x 3-2. Page . . . 108 



Fig. 18. Cladodus prototypus Eastm. Columbus limestone 

 (Middle Devonian) ; Columbus, Ohio. Detached tooth serving 

 as holotype of the species, seen from the posterior face ; coronal 

 cross-section shown at the right. Original in American Mu- 

 seum of Natural History, New York, x 2-1. Page 108 



297 



