NIAGARA FALLS AND VICINITY I9I 



valves in some specimens; surface marked only by concentric lines 

 of growth, which are strongest in old shells. 



Fig. 103 Pentamerus oblongus 



Found in the upper crystalline Clinton limestone at Niagara 

 (I specimen). The species is characteristic of the lower Clinton 

 limestone, east of Lockport. 



Genus barrandella Hall & Clarke 



[Ety. : proper name] 



(Hall & Clarke. 1894. Pal. N. Y. v. 8, pt 2, p. 241, 243) 



Small pentameroid shells, of a galeate form or helmet-shaped con- 

 tour, with a smooth, or rarely plicated surface. A spondylium is 

 present, but is not supported by a septum. 



Barrandella fornicata (Hall) (Fig-. 104). Pentamerus 

 fornicatus Hall (Fal. N. Y. 2:81, pi. 24) 



_ , Distinguishing characters. Helmet- 



shaped contour, very convex pedicle 

 |Jp valve, with overarching beak; sur- 

 face obscurely plicate longitudinally. 

 Fig. 104 Barrandella fornicata Found in the upper crystalline 



Clinton limestone at Niagara. Also in the same limestone at 

 Lockport (Hall). 



