EXPLANATION OF PLATE LIII. 



Figs. 1-2. SPIRIFER GRIMES: Hall p 3^ 



1. Interior view of a pedicle valve. (W. M., No. 10762.) 2. View 

 of an incomplete pedicle valve with the plications not worn, 

 showing bifurcation. (W. M., No. 14786.) 



Burlington limestone, near Springfield, Missouri. 



Figs. 3-6. SPIRIFER ROWLEYI n. sp _ p 350 



3-4. Pedicle and brachial views of a nearly complete specimen. 

 5. Lateral view of another example. (W. M., No. 14783.) 



Lake Valley Beds, Lake Valley, New Mexico. 

 6. View of a worn pedicle valve. (W. M., No. 13919.) 

 Fern Glen formation, Fern Glen, Missouri. 



Fig. 7. SPIRIFER sp. 



Pedicle view of a nearly complete specimen. (W. M., No. 5653.) 

 Keokuk limestone, near Springfield, Missouri. 



Figs. 8-9. BRACHYTHYRIS BURLINGTONENSIS n. sp p. 371 



8. View of a plaster cast from a natural mould, partially restored. 

 9. View of the natural internal cast of the same specimen. 

 Cotypes. (W. M., No. 13543.) 



Kinderhook, Bed No. 5, Burlington, Iowa. 



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