NIAGARA FALLS AND VICINITY 



187 



Fig. 96 Orthostrophia (?) fasciata 



Orthostrophia ( ?) fasciata Hall (Fig. 96). Orthis fasciata 

 Hall (1852. Pal N. Y. 2:255, pi. 52) 



Distinguishing characters. Semi- 

 oval contour; produced hinge 

 line; clustered or fasciculated 

 striae almost simple at their origin, 

 dividing toward the margin. 



Found in the lower Rochester shale at Niagara (?). Also at 

 Lockport (Hall). 



Genus dalmanella Hall & Clarke 



[Ety. : proper name] 



(1892. Pal. N. Y. v. 8, pt I, p. 205, 223) 



Shells plano-convex or subequally biconvex; pedicle valve usually 

 the deeper, often elevated at the umbo and arched over the cardinal 

 area; hinge line generally shorter than the greatest width of the 

 shell; surface finely striate. Prominent teeth supported by lamellae 

 which circumscribe the muscular area; cardinal process tri- to 

 •quadrilobed, continued downward in a median ridge dividing a 

 ■quadriplicate muscular area. 



Dalmanella elegantula (Dalman) (Fig. 97). Orthis e 1 e g a n- 

 tula Dalman (Hall 1852. Pal. N. Y. 2:252, pi. 52, fig. 3a-r) 



Distinguishing characters. Strongly con- 

 vex pedicle valve with high but narrow area 

 and incurved beak; nearly fiat brachial valve; 

 generally wdth a longitudinal concavity in 

 the center; fine close set striae, which divide 

 dichotomously toward the margin; ex- 

 tremely fine concentric lines and coarser 

 growth lines. 



Found in the Clinton lenses, and abundantly at intervals in the 

 lower and middle (Bryozoa beds) Rochester shales at Niagara. 

 Also at Lockport and elsew^here (Hall). 



^;. 



Fig. 97 Dalmanella elegantula 



