260 EXPLANATION OF PLATES. 



PLATE XXXIIL 



Exhibits the dental armature of Rays, with the fore part or worn extremity directed upward. 



All of the natural size. 

 Figs. 1-3. Myliobates mordax. 1. An inferior dental plate ; the right half alone represented. 



Specimen from the Ashley phosphate beds. 



2. A second specimen, from tlie same locality. 



2a. A transverse section of the same, with the crown directed upward. 



3. A superior dental plate, probably of the same species. From the same locality. 



4. Myltobates GiaAS, Cope. 



A superior dental plate. From the miocene tertiary of Charles Co., Md. 



5. Myliobates vioomicanus. Cope. 



An inferior dental plate. Found with the preceding. 



6. Myliobates fastigiatus. A superior dental plate. 



6a. Transverse section of the same, with the crown directed downward. From Monmouth 

 Co., N. J. 

 1. Myliobates magister. 



An inferior dental plate. From the Ashley phosphate beds. 



PLATE XXXIV. 



Figs. 1, 2. Ceratoptera unios. Figures of the natural size. Bony knob of the tail. 



I. Upper view. 2. Lateral view, the hinder extremity directed towards the left. 



3. Tbionyx. Fragment of a costal plate, half the natural size. 



4, 5. Eupaohemys obtusus. . 



Figures half the natural size. A marginal bone of the carapace. 



4. Upper view. 5. View of the posterior sutural surface; the upper surface of the bone 



directed towards the left, and the inner margin of the bone upward. 



6. DiNOZiPHius oarolinensis. a tooth, one-half the natural size. 



7. Ceterhinops longifrons. Upper view of a fragment of the skull, one-half the natural 



size. The occipital extremity is uppermost. 

 8, 9. Gryphodobatis uncus. A tooth magnified two diameters. 



8. External or anterior view. 9. Internal or posterior view. 

 10-13. Aorodobatis serra. 



Four teeth, viewed on the anterior or external face, magnified two diameters. 

 10. Tooth with the principal point worn off. 11, 12. Teeth less worn. 



13. Tooth retaining its principal point. 



14. Aorodobatis obliquus. 



Tooth magnified two diameters, external view. Specimen from Monmouth Co., N. J. 

 15-18. DiODON vetus. Dental armature of the jaws, natural size. 



15a. Dental armature of the lower jaw, viewed on the upper or oral surface. 

 156. The same specimen seen on the under surface. 

 16. Dental armature of the upper jaw, viewed on the under or triturating surface. 



II. View of the triturating surface of two piles of oral plates from another specimen. 

 18. View of the upper surface of the same specimen. 



