EXPLANATION OF PLATE IX. 



Figs. 1-10. PRODUCTUS BURLINGTONENSIS Hall p. 104 



1-3. Pedicle, posterior and lateral views of a pedicle valve. 

 4-5. Pedicle and posterior views of another pedicle valve. 

 (W. M., No. 14303.) 6-8. Pedicle lateral and posterior views 

 of a nearly perfect pedicle valve. (W. M., No. 14287.) 

 Burlington limestone, Burlington, Iowa. 



9. View of a somewhat imperfect specimen of the interior of a 

 brachial valve. (W. M., No. 345.) 



Burlington limestone, Springfield, Missouri. 



10. View of a nearly complete specimen from the brachial side, 

 showing the concave brachial valve. (W. M., No. 14288.) 



Burlington limestone, Quincy, Illinois. 



Figs. 11-17. PRODUCTUS FERNGLENENSIS Weller p. 105 



11-13. Pedicle, posterior and lateral views of a nearly complete 

 pedicle valve. 14. View of another pedicle valve. 15. View 

 of a large pedicle valve. 16. View of a brachial valve from 

 the interior, showing the cardinal process ; over the greater 

 portion of the specimen the shell substance has been destroyed 

 so that an impression of the exterior of the valve is exposed. 

 Cotypes. (W. M., No. 4669.) 



Fern Glen formation, near Kinnnswick, Missouri. 

 17. View of a pedicle valve. (W. M., No. 8556.) 



Pier son limestone, near Springfield, Missouri. 



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