Prod. 



758 



others.) Collett's Indiana Eeport of 1883, page 126, plate 26, 

 figs. 1, 2, natural size^ ordinary example; fig. 3, ventral view 

 of another example showing finer radiating lines and the 

 absence of spines on the general surface. Owen and Marcou 

 referred the^shell of our western States to D'Orbigney's South 

 American form correctly, in Collett's opinion, after examining 

 Dr. Darby's more recent specimens. Shells sometimes large. — 

 XIII, Sometimes occurs in Lower Carboniferious strata also. 

 Collett. — Stevenson found it in the Crinoidal limestone of- the 

 Barren measures on the Monongahela river. Pa. Report K, 

 page 80. XIV. — Heilprin found the upper half of a large 



I PRODUCTUS CORA. 



valve, and also a nearly perfect round ventral valve of this 

 in the Wyoming Hist. Soc. collection of anthracite fossils near 

 Wilkes-Barre, Pa., from the Mill creeh limestone, which lies 

 1000 feet above the Pottsville conglomerate, and probably 

 corresponds to the Great limestone of the Monongahela region. 

 See Geol. Sur. Pa. An. Rt. 1885, page 440, 452, figs. 1, lA.— 

 XI Vf XV? 



Pr oductus cora, d'Orbigny. Dawson's Acadian Geology, 



^^a 1868, page 297, fig. 98 a, dor- 

 sal, i ventral valve, is iden- 

 tical with P, conoides and 

 jP. scoticus,, De Kon. (not of 

 Sow.), P. corrugata, McCoy, 

 ge -sHBB^ -z V ^— ,,ix of Ireland, P. lyeUi,T>eYeY,<i 



P, tenuistriata and' P. 7ieiFedievi^ DeVer. of Russia, P. pilei 



