EXPLANATION OF PLATE XLIII. 



Figs. 1-10. SPIRIFER SUB^EQUALIS Hall p. 327 



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

 nearly perfect specimen. (D. K. G., No. 3501.) 



Webb City, Jasper Co., Missouri. 



6-10. Pedicle, brachial, lateral, posterior and anterior views of a 

 sulphur cast of the holotype. (W. M., No. 14773.) 

 Warsaw limestone, Warsaw, Illinois. 



Figs. 11-15. SPIRIFER LATERALIS Hall p. 330 



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

 type. (W. M., No. 8619.) 



Clifton, Madison County, Illinois. 



Fig. 16. SPIRIFER FORBESI Norwood and Pratten p. 331 



View of a pedicle valve. (W. M., No. 13549.) 



Burlington limestone, Pettis County, Missouri. 



Fig. 17. SPIRIFER IMBREX Hall p. 334 



View of a brachial valve, the holotype. (A. M. N. H., 5110 1.) 

 Burlington limestone, Burlington, Iowa. 



102 



