32 UNIVERSITY OF MISSOURI BULLETIN 



attention to this part never having been figured or described 

 and accounted for its usually being lost in specimens because 

 of the slime canal crossing the anterior end, as shown in the 

 figure. 



EXPLANATION OF PLATES 



Plate I 



Figs. 1-4, Rhadinichthys sp. nov. 



Fig. 1, Maxilla showing sculpturing. 



Fig. 2, Mandible showing sculpturing. 



Fig. 3, Scale showing markings (15). 



Fig. 4, Head plates showing sculpturing. 



Fig. 5, Scale of Rhadinichthys sp. ? from near bottom of 

 Ohio shales (15). 



Fig. 6, Scale of Rhadinichthys sp. ? from three feet from 

 the top of the Ohio shales (15). 



Fig. 7, Lingula spatulata Vanuxem (2) from Huron shale. 



Fig. 8, Mandible of Stenosteus pertenuis Dean. 



Fig. 9, External occipital of Dinichthys sp. ? 



Fig. 10, Section of mandible of Stenosteus pertenuis near 

 proximal end. 



Fig. 11, Section of mandible of Stenosteus pertenuis near 

 distal end. 



Fig. 12, Section of tooth of Elasmobranch from top of 

 Olentangy shale. 



Fig. 13, Anterior view of same tooth. 



Fig. 14, Antero-dorso-median of an ostracoderm. 



Plate II 



Mandible of Dinichthys subgracilis sp. nov. (Holotype) 

 Plate III 



Dinichthys terrelli Newberry. Photograph of almost com- 

 plete specimen. Left mandible placed on right side to show its 

 length compared with the length of the suborbital. 



