GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 



183 



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

 hj its reversed form and strong rugose striae ; Meristella 

 n a s 11 1 a [fig. 99], abundantly represented by molds of the 

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

 dental plates are most consipicuoois ; P e n t a m e r e 1 1 a a r a t a 

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

 and the strong angular plications and A t r y p a i m p r e s s a 

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

 center of the ventricose braichial valve, Avith bifurcating radii, and 





Fig-. 99 Meristella nasuta 



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 ; Conocardium cuneus [fig. 103] , recog- 

 nized by its form and sharp radii ; and Panenka dicho- 

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

 by bifurcating radii. 



The common gastropods are : Pleurotomaria arata 



[fig. 105]^ chieflj' represented by internal molds, and readily 



recognized by their form, low spire, depressed rounded whorls 



and deep and large umbilicus ; Bellerophon curvilin- 



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



