EXPLANATION OF PLATE LII. 



Figs. 1-4. SPIRIFER GRIMESI Hall p. 361 



1-3. Anterior, posterior and lateral views of the specimen illus- 

 trated on Plate LI, Figs. 1 and 2. (W. M., No. 12942.) 4. View 

 of a pedicle valve in the usual condition of preservation. (\Y. 

 M., No. 331.) 



Burlington limestone, Springfield, Missouri. 



Figs. 5-11. BRACK YTHYRIS FERNGLENENSIS Weller p. 372 



5. Lateral view of a pedicle valve. 6. View of another pedicle 

 valve. Cotypes. (W. M., No. 13538.) 7-11. Pedicle, brachial, 

 lateral, anterior and posterior views of a nearly perfect speci- 

 men. (D. K. G., No. 3101.) 



Fern Glen formation, Fern Glen, Missouri. 



120 



