EXPLANATION OF PLATE XLI. 



Figs. 1-5. SPIRIFER INSCULPTUS Rowley p. 324 



Pedicle, brachial, posterior, anterior and lateral views of the holo- 

 type. (R. R. R.) 



Lower Burlington limestone, Louisiana, Missouri. 



Figs. 6-14. SPIRIFER INCERTUS Hall p. 335 



6. View of a nearly perfect pedicle valve. (W. M., No. 13529.) 

 7-11. Lateral, pedicle, brachial, posterior and anterior views of 

 a nearly perfect specimen. (W. M., No. 8620.) 12-14. Bra- 

 chial, posterior and pedicle views of the holotype. (A. M. 

 N. H., No. 51111.) 



Burlington limestone, Burlington, Iowa. 



98 



