EXPLANATION OF PLATE LXXIX. 



Figs. 1-11. CLIOTHYRIDINA OBMAXIMA (McChesney) p. 475 



1. View of a large pedicle valve. (W. M., No. 7592.) 

 Fern Glen formation, Monroe County, Illinois. 



2-6. Pedicle, brachial, anterior, posterior and lateral views of a 

 nearly perfect specimen! (W. M., No. 13917.) 

 Fern Glen formation, Chautauqua, Illinois. 



7-11. Pedicle, brachial, anterior, lateral and posterior views of a 

 nearly perfect specimen. (W. M., No. 7596.) 

 Keokuk limestone, Keokuk, Iowa. 



Fig. 12. CLIOTHYRIDINA INCRASSATA (Hall) p. 4/7 



View of a pedicle valve. (W. M., No. 342.) 



Burlington limestone, Springfield, Missouri. 



Figs. 13-16. CLIOTHYRIDINA PROUTI (Swallow) p. 474 



Pedicle, brachial, anterior and lateral views of a nearly perfect 

 specimen. (W. M., No. 46951.) 



Fern Glen formation, near Kimmswick, Missouri. 



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