Placodeemata. 



Fig. 33. 



Fig. 34. 



Fig. 33.— Dorsal surface of Pterichthys MiUeri (after Pander), 



Old Red Sandstone, Scotland. 

 Fig. 34. — Ventral surface of Pterichthys cornutus, Agassiz, 



Old Red Sandstone, Scotland. 



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Fig. 35. — Coccos re us (side-view), Old Red Sandstone. 



Fig. 36.— Coccosteus decipiens (dorsal aspect), Agassiz. 



Fig. 37.— Jaws of Dinichthys, Devonian, North America. 



