433 



Mya 



n Z9. 



(leol. Report, page 307, plate C, fig. 17.) Collett's Indiana 

 Geol. Eeport for 1883, page 140, plate 29, fig. 1, out side of 

 right valve, with unusually narrow base, natural size ; fig. 2, 

 in side of same YB,\Ye,— JJpper Coal Measures in Knox, Gibson 

 and Posey counties, Ind.—XF:— Recognized as several frag- 

 mentary casts and impressions, by Heilprin among the fossils 

 in the Mus. Wyoming Hist. Soc. at Wilkes-Barre, from the Mill 

 Creek limestone, 1,000' above the base of the Anthracite Coal 

 28 



