EXPLANATION OF PLATE V. 



Figs. 1-19. STREPTORHYNCHUS RUGINOSUM (Hall & Clarke) p. 71 



1-5. Pedicle, brachial, lateral, posterior, and anterior views of the 

 holotype. (W. M., No. 11912.) 



St. Louis chert, Providence, Indiana. 



6-9. Pedicle, brachial, posterior, and lateral views of a nearly com- 

 plete specimen. (W. M., No. 10129.) 



St. Louis limestone, St. .Louis, Missouri. 



10-11. View of an internal cast, and a plaster cast of the natural 

 mould of the exterior of the same specimen. One of the 

 cotypes of S. williamsi Weller. (W. M., No. 4956.) 

 Baicsville sandstone, Batesville, Arkansas. 



12. View of a pedicle valve. (W. M., No. 14759.) 



St. Louis limestone, Alton, Illinois. 



13. View of an internal cast of a nearly complete brachial valve. 

 14. View of an internal cast of a pedicle valve. (W. M., No. 

 14758.) 



Salem limestone, Hull's Hollow, near Alton, Illinois. 

 15. View of the internal cast of a small pedicle valve. 16. View of 

 the internal cast of a brachial valve. (W. M., No. 282.) 



Residual chert, Springfield, Missouri. 



17-18. Pedicle and brachial views of a nearly complete specimen. 

 (W. M., No. 10922.) 



St. Louis limestone, Alton, Illinois. 



19. View of a nearly complete pedicle valve. (W. M., No. 10129.) 

 St. Louis limestone, St. Louis, Missouri. 



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