TJie Fauna of the Maxvillc Limestone. 373- 



1860. Prodnctus ccstrieiisis. Worthen, Trans. St. Louis Acad. Sci., 

 Vol. I, p. 570. 

 Chester limestone : Chester, Illinois. 

 1877. Productus elegans. Hall and Whitfield, U. S. Geol. Expl. 40 Par.,, 

 Vol. IV, p. 268, pi. 5, figs. 3, 4. 

 Lower Carboniferous limestone: Utah. 

 1891. Productus elegans. Whitfield, Ann. N. Y. Acad. Sci., Vol. V, p. 

 581, pi. 13, figs. 15, 16. 

 Maxville limestone : Ohio. 



1894. Productus cestriensis. Keyes. Mo. Geol. Surv., Vol. V, p. 44. 

 Kaskaskia limestone : Ste. Mary, Missouri. 



1895. Productus elegans. Whitfield, Geol. Surv. Ohio, Vol. VII, p. 469,. 



pi. 9, figs. 15, 16. 

 Maxville limestone : Ohio. 

 1897. Productus cestriensis. Weller, Trans. N. Y. Acad, Sci., Vol. XVT,. 

 p. 256, pi. 19, figs. 7-9. 

 Batesville sandstone : Batesville, Arkansas. 

 1911. Diapliragmits elegans. Girty, U. S. Geol. Surv., Bull. 439, p, 51> 

 pi. 4, figs. 4, 5. 

 Moorefield shale : Batesville quadrangle, Arkansas 



Description. — Shell of meditim size, highly curved. Hinge 

 line straight and short. 



Pedicle valve strongly cm'ved, gradually increases in hreadth 

 from the beak tow^ard the anterior end where it is slightly ex- 

 panded in the older forms. Auricular depressions at the extrem- 

 ities of the hinge line very small. In many specimens a shallow, 

 ill-defined sinus extends from near the beak to the anterior end. 

 Surface marked with numerous, mediimi-sized, radiating plica- 

 tions which bear a ntmiber of spine bases. Plications crossed by 

 concentric wrinkles in the posterior region. 



Brachial valve with central portion nearly flat or concave 

 and with anterior half bending abruptly forward and fitting in 

 the opposite valve so as to greatly restrict the viseral cavity. 

 Surface ornamented with medium-sized, radiating plications 

 which are less distinct on the flattened portion and which, in this 

 area, are crossed by concentric wrinkles. 



Length i6 mm.; wadth i6 mm. 



This species is characterized by the highly curved pedicle 



