NIAGARA FALLS AND VICINITY 1 87 



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

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



Distinguishing characters: Semi- ^^*^^. .w 



-ff -. _ - — -— ■ V- — =*^ 



oval contour; produced hinge 

 line; clustered or fasciculated 

 striae almost simple at their origin, 



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



dividing toward the margin. 



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

 iockport (Hall). 



Genus dalmanella Hall & Clarke 



[Ety. : proper name] 



(1892. Pal. N. Y. v. 8, pt 1, 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 elegan- 

 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 flat brachial valve; 

 generally with a longitudinal concavity in 

 the center; fine close set striae, which divide 

 dichotomously toward the margin; ex- 

 tremely fine concentric lines and coarser 



Kg. 97 Dalmanella elegantula . . . 



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 elsewhere (Hall): 



