EXPLANATION OF PLATE XXXI. 



FigS. 1-4. DlELASMELLA CALHQUNENSIS n. Sp p. 281 



1-3, Pedicle, brachial and lateral views of a nearly complete speci- 

 men. 4. View of a partially exfoliated pedicle valve. (W. M., 

 No. 14246.) 



Hamburg oolite, Kinderhook, Hamburg, Illinois. 



Figs. 5-15. CENTRONELLOIDEA ROWLEYI (Worthen) p. 247 



5-6. Views of a pedicle and a brachial valve, the cotypes. (I. S. 

 M.) 7-10. Pedicle, brachial, lateral and anterior views of a 

 nearly perfect specimen. 11-14. Pedicle, brachial, lateral and 

 posterior views of another specimen. 15. View of the brach- 

 idium. (R. R. R.) 



Burlington white chert, Louisiana, Missouri. 



Figs. 16-18. HAMBURGIA TYPA n. sp p. 283 



16-17. Views of two pedicle valves. 18. View of a brachial valve. 

 (W. M., No. 14245.) 



Hamburg oolite, Kinderhook, Hamburg, Illinois. 



Figs. 19-24. DIELASMOIDES BISINUATA Weller p. 254 



19-21. Pedicle, brachial and lateral views of a nearly complete speci- 

 men. 22-24. Similar views of a larger specimen. (D. K. G., 

 No. 1704.) 



Patrick's Quarry, Middle Fabius River, Lewis County, Mis- 

 souri. 



Figs. 25-27. DIELASMA SHUMARDANUM (Miller) p. 268 



Lateral, pedicle and brachial views of a nearly perfect specimen. 

 (W. M., No. 7770.) 



Chester group, Big Hill, Jackson County, Illinois. 



Figs. 28-34. DIELASMA SINUATA n. sp p. 262 



28-31. Pedicle, brachial, lateral and posterior views of a nearly com- 

 plete internal cast, somewhat restored anteriorly. 32-33. Views 

 of the internal casts of two brachial valves. (W. M., No. 334.) 



Residual chert, Springfield, Missouri. 



34. View of the internal cast of a brachial valve, the holotype of 

 Lingula crawfordsvillensis Gurley. (W. M., No. 6315.) 

 Crawfordsville shale, Crawfordsville, Indiana. 



Figs. 35-44. DIELASMA ARKANSANUM n. sp p. 269 



35-37. Pedicle, brachial and lateral views of a nearly complete speci- 

 men. 38-40. Similar views of a smaller example. (D. K. G., 

 No. 1505.) 



Webb City, Missouri (Carterville formation?). 

 41-43. Pedicle, brachial and lateral views of a nearly complete 

 specimen. 44. Pedicle view of another specimen. Cotypes. 

 (W. M., No. 14255.) 



Fayetteville, Arkansas. 



Figs. 45-49. DIELASMA BURLINGTONENSIS (White) p. 261 



45-47. Pedicle, brachial and lateral views of a nearly perfect but 

 slightly distorted specimen. 48-49. External and internal views 

 of a pedicle valve, imperfect anteriority. Cotypes. (U. M., 

 No. 1373.) 



Base of Burlington limestone, Burlington, Iowa. 



72 



