I 



PALEONTOLOGY. 

 PLATE IV. 



Page. 

 AvicuLA (Oxytoma) mucronata 357 



Fig. 1. View of a left valve partly restored, showiug the usual form of the specimens. 

 Fig. 2. \'iew of the right valvo enlarged to twice the natural size, posterior margin re- 

 stored to correspond with the lines of growth. 



Oervillia recta 358 



Fig. 3. View of a left valve, natural size. 



Camptonectes extenuatus :Jo:i 



Fig. 4. View of a very large left valve of the species from a locality east of Belle Fourche. 

 Fig. r>. View of smaller specimen, from the same Icoality, from which the surface shell has 

 been removed, the conditiou in which they arc usually found. 



Camptonectes bellistriata 351 



Fig. 6. View of a right valve, the .surface partially exfoliated. From Belle Fourche. 



Fig. 7. View of a left vsllve, imperfect on one side, showing the surface striic. From Belle 

 Fourche. 



Fig. 8. View of the interior of a large right valvo from Big Horn Mountains, showing 

 the features of the type fo;rin of the species. 



Fig. 9. Exterior of a left valve, showing the surface stria;. 



Fig. 10. Exterior of a right valve ; no striae are visible on the specimen, whether from exfo- 

 liation or naturally so is not readily detennined. All right valves seen have 

 the surface smooth. 



Fig. 11. Enlargement of the surface as seen on specimens Figs. 6, 9. 



Pecten Newijeuryi 350 



Fig. 1'2. View of a left valve, ijnperfect on the anterior side of the cardinal line. 

 Fig. l:{. A'iew of another individual, showing the entire form. 

 Fig. 14. Enlargement of the surface, showing the elevated concentric strise. 

 Fig. 15. View of a right valve associated with the preceding, and supposed to be of the 

 same species. 



