108 
Plate V 
Orthis marshalli n. sp. 
Figure 1 . Pedicle valve. X 2. (Page 24.) 
Figure 2. Area of pedicle valve, showing teeth. X 2. (Page 24.) 
Figure 3. Brachial valve. X 2. (Page 24.) 
Figure 4. Interior of pedicle valve showing the muscle scars. Cardinal area and teeth broken 
away. X 4. (Page 24.) 
Figure 5. Interior of brachial valve. X 4. (Page 24.) 
Figure 6. Interior of pedicle valve taken at right angles to the dental plates showing the supports. 
(Page 24.) 
Dinorthis Columbia n. sp. 
Figure 7. Beaks from the brachial valve, showing the angular external face of the cardinal pro- 
cess, taken at a very sliglit angle. (Page 25.) 
Figure 8. An incomplete and rather small specimen of the brachial valve, showing the broad, 
shallow sinus, and the presence of one or two implanted striae. (Page 25.) 
Figure 9. Interior of pedicle valve. (Page 25.) 
Figure 10. Interior of brachial valve, showing spear-head cardinal process. (Page 25.) 
Dinorthis rockymontana n. sp. 
11. Brachial valve, showing a part of the area of the pedicle valve. (Page 26.) 
12. Profile showing the beaks. (Page 26.) 
13. Interior of the brachial valve, showing the bifid cardinal process. (Page 26.) 
14. Interior of the pedicle valve, showing the arrangement of the muscle scars. (Page 26.) 
Petroria rugosa nov. gen. n. sp. 
Figure 15. Pedicle valve. (Page 28.) 
Figure 16. Brachial valve showing projection of pedicle beak. X 2. (Page 28.) 
Figure 17. Hinge of brachial valve, showing the thickened end of the cardinal process filling the 
opening. X 4. (Page 28.) 
Figure 18. Interior of the brachial valve, from the anterior margin, showing the thickened 
cardinal process, and one triangular crural plate. X 4. (Page 28.) 
Byssonychia radiata var. walkeri n. var. 
Figure 19. Left valve, showing the general outline of the shell. The angle of the fracture at the 
beak erroneously suggests a curve to the right instead of the true turn to the left. (Page 29.) 
Figure 20. Anterior view of the same valve, showing the ventricose nature of the shell and the 
large ligamental area below the broken type of the beak. (Page 29.) 
Figure 
Figure 
Figure 
Figure 
