224 Pirsson and Schuchert — OrisTcany Formation. 



closely related to S. pirsso?iai, but although both are 

 fimbriate Spirifers, they are clearly of different stocks. 

 The two forms are not associated in the same layers. The 

 species under discussion is more quadrate than the fore- 

 going one, has a narrower ventral cardinal area, and 

 therefore is also less thick shelled and less rostrate in 

 these parts. It differs chiefly, however, from S. pirs- 

 sonce- in having a wider and more flabellate ventral 

 muscle field. As the material is hardly good enough to 

 figure, the form is left unnamed for the present. 



Meristella lata (Hall) ? A single much squeezed example. 

 Mensselceria callida Clarke. Rare, and much smaller than 

 the original material. 



Gasteopoda. 



Plectonotus derby i Clarke. One specimen. 

 Tropidodiscus obex Clarke. One specimen. 



Yale University, New Haven, Conn., Dec, 1913. 



