i86 



NEW YORK STATE MUSEUM 



s.> 



Fig. 94 Orthis flabellites 



valve elevated and somewhat incurved; dental lamellae slightly de- 

 veloped, not extending the entire length of the umbonal cavity. Car- 

 dinal process an elongate vertical plate, logitudinally dividing the 

 deep deltidial cavity. 



Orthis flabellites Foerste 

 (Fig. 94). Orthis f 1 a - 

 b e 1 1 u 1 u m var. Hall (1852. 

 Pal. N. Y. 2:254, pi. 52) 



D istingnishing characters. 

 Long hinge line; semioval 

 form; coarse, simple rounded 

 plications, equal to spaces 

 between them; marked con- 

 centric growth lines. 



Found in the upper Clinton 

 limestone and the lower Rochester shale at Niagara. Rare. Also 

 in the shale at Lockport (Hall). 



Orthis ( ?) punctostriata Hall (Fig. 95) 

 (1852. Pal. N. Y. 2:254, pi. 52, fig. 5a-f) 



Distinguishing characters. Subglobose 

 contour, nearly equal, extremely convex 

 valves; beak of pedicle valve somewhat 

 longer than that of brachial valve, but both 

 prominent; short hinge line, still shorter 

 but high area; fine equal bifurcating striae; 

 extremely fine concentric striae; punctate 

 interspaces. 



Foimd in the talus of Rochester shale above Lewiston hights. 

 Rare. Also in the shale at Lockport (Hall). 



r>.^ 



Fig. 95 Orthis (?) punctostriata 

 with enlargement of surface 



Genus orthostrophia Hall 



[Ety.: the name refers to the relations of the genus to Orthis 

 and Strop heodonta] 



(1883. A", y. state geol. 2d an. rep't, pi. 36; 1892. Pal. N. Y. 

 V. 8, pt I, p. 199, 223, 253) 



Shells with convexity of valves reversed; surface finely plicated; 

 deep narrow muscular area; cardinal process elongate and simple. 



