NIAGARA FALLS AND VICINITY 



203 



Whitiieldella oblata Hall (Fig. 125). Atrypa oblata Hall 

 .{1852. Pal. N. Y. 2:9, pi. 4) 



Distinguishing characters. Oblate form, nearly as broad as high; 

 broadest anteriorly; sloping abruptly to the beak; small, well 



Fig. 125 Whitfleldella oblata 



•defined beak; nearly equally convex valves; central groove on 

 pedicle valve and slight elevation on brachial valve; surface marked 

 •only by lines of growth. 



Found in the upper Medina sandstone at Niagara. Also at 

 Lockport (Hall). 



Whitiieldella intermedia Hall (Fig. 

 126). Atrypa intermedia Hall 

 {1852. Pal. N. Y. 2:77, pi. 24) 



Distinguishing characters. Obovate; 

 rapidly expanding to front, which is 

 abruptly rounded; length and width 

 nearly equal; convex near beak, flatter 

 toward front; slight frontal sinuosity; '- 

 faint growth lines. 



Found in the Clinton lenses and 

 lowest Clinton shales at Niagara. Also in the upper Clinton lime- 

 stone at Lockport (Hall). 



Whitfieldella cylindrica Hall (Fig. 127). Atrypa cylin- 

 d r i c a Hall (1852. Pal. N. Y. 2:y6, pi. 24) 



Fig. 136 Whitfieldella intermedia 



Fig. 127 Whitfleldella cylindrica 



Distinguishing characters. Elongate cylindric; strongly convex; 

 aiearly as wide as thick ; strongly overarching beak of pedicle valve ; 



