EXPLANATION OF PLATE LXXII. 



Figs. 1-4. SYRINGOTHYRIS PLATYPLEURUS n. sp p. 397 



1-3. Posterior, anterior and lateral views of a nearly complete 

 internal cast. Holotype. (W. M., No. 13955.) 



Residual chert, Sedalia, Missouri. 



4. View of the inner surface of the cardinal area of a pedicle valve 

 showing the delthyrial plate with the syrinx. (W. M., 

 No. 7914.) 



Burlington limestone, Osceola, Missouri. 



Figs. 5-12. SYRINGOTHYRIS EXTENUATUS (Hall) p. 386 



5-6. Posterior and pedicle views of a nearly complete pedicle valve. 

 7. View of the cardinal area of another specimen. (W. M., 

 No. 13960.) 



Kinderhook, Bed No. 3, Burlington, Iowa. 



8-12. Posterior, anterior, brachial, pedicle and lateral views of a 

 nearly complete internal cast. (W. M., No. 5929.) 

 Chonopectus sandstone, Burlington, lozua. 



Figs. 13-23. SYRINGOTHYRIS HALLI W'inchell p. 390 



13-17. Posterior, anterior, pedicle, brachial and lateral views of 

 one of Winchell's cotypes. (W. M., No. 1369.) 

 Kinderhook, Bed No. 4, Burlington, Iowa. 



18-22. Posterior, anterior, pedicle, brachial and lateral views of a 

 nearly complete specimen. 23. View of a very perfect brachial 

 valve. (W. M., No. 4614.) 



Kinderhook, Bed No. 4, Flint River, near Burlington, Iou<a. 



160 



