GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 183 



a m p 1 a [fig. 98], the largest of these brachiopods, characterized 

 by its reversed form and strong rugose striae ; Meristella 

 nasuta [fig. 99], abundantly represented by molds of the 

 interior in which the muscular scar and the marks of the strong 

 dental plates are most conspicuous ;Pentamerella a rata 

 [fig. 100], marked by the overarching beak of the pedicle valve 

 and the strong angular plications and Atrypa impressa 

 [fig. 101], an extremely convex form with a flattening on the 

 center of the ventricose brachial valve, with bifurcating radii, and 



strongly marked muscular impression shown in the internal mold, 

 the most common condition of preservation of the shell. 



The pelecypods are represented by a number of species. Among 

 these are G o n i o p h o r a p e r a n g u 1 a t a [fig. 102] , charac- 

 terized by an extremely sharp umbonal ridge, above which the 

 shell is concave ; C o n o c a r d i u in c u n e u s [fig. 103] , recog- 

 nized by its form and sharp radii ; and Panenka d i c h o- 

 toma [fig. 104], characterized by a prominent beak and often 

 by bifurcating radii. 



The common gastropods are : P 1 e u r o t o m a r i a a r a t a 

 [fig. 105], chiefly represented by internal molds, and readily 

 recognized by their form, low spire, depressed rounded whorls 

 and deep and large umbilicus ; Bellerophon c u r v i 1 i n - 

 eat us [fig. 106], with a discoidal form, sharp peripheral 



Fig. 99 Meristella nasuta 



