EXPLANATION OF PLATE XXXV. 



Figs. 1-5. ATRYPA INFREQUENS n. sp p. 285 



1-2. Pedicle and brachial views of the holotype. 3-5. Pedicle, 

 brachial and lateral views of the same specimen enlarged x 2. 

 (W. M., No. 11348.) 



Glen Park limestone, Glen Park, Missouri. 



Figs. 6-21. CYRTINA ACUTIROSTRIS (Shumard) p. 286 



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

 perfect specimen. 11-15. Similar views of another specimen. 

 16-20. Similar views of a third example. 21. View of the 

 interior of a pedicle valve showing the median septum. (W. 

 M., No. 6691.) 



Louisiana limestone, Louisiana, Missouri. 



Figs. 22-31. CYRTINA BURLINGTONENSIS Rowley.... p. 288 



22-26. Pedicle, brachial, lateral, anterior and posterior views of 

 a perfect specimen. (W. M., No. 9676.) 



Choutcau limestone, Peltis County, Missouri. 

 27-30. Pedicle, brachial, lateral and anterior views of the holo- 

 type. (R. R. R.) 



Burlington white chert, Louisiana, Missouri. 



31. View of an internal cast of a pedicle valve showing the 

 median septum as a slit. (R. R. R.) 



Burlington chert, Louisiana, Missouri. 



Figs. 32-38. CYRTINA NEOCENES Hall and Clarke p. 289 



32-36. Pedicle, brachial, anterior, posterior and lateral views of 

 a nearly complete internal cast. 37-38. Views of two internal 

 casts of pedicle valves. (W. M., No. 5638.) 

 Residual chert, Springfield, Missouri. 



Figs. 39-40. SPIRIFERINA sp. 



Pedicle and brachial views of a somewhat crushed specimen. (W. 

 M., No. 7531.) 



Keokuk limestone, Keokuk, Iowa. 



Figs. 41-49. SPIRIFERINA TRANSVERSA (McChesney) p. 297 



41-44. Pedicle, brachial. anterior and posterior views of a very 

 perfect specimen. 45-48. Similar views of another example. 

 49. View of the interior of a pedicle valve showing the dental 

 lamellae and median septum. (W. M., No. 7507.) 

 Chester Group, Chester, Illinois. 



Figs. 50-58. SPIRIFERINA SPINOSA (Norwood and Pratten) p. 299 



50-53. Pedicle, brachial, anterior and posterior views of a nearly 

 perfect specimen. (W. M., No. 7496.) 



Chester Group, Randolph County, Illinois. 



54-58. Pedicle, brachial, anterior, posterior and lateral views of 

 another specimen. (W. M., No. 7498.) 



Chester Group, Monroe County, Illinois. 



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