Pinna. 



646 



Pinna peracuta, (Shumard. Trans. St. Louis Ac. Sc. I, 214.) 



Collett's Ind. Geo- 

 logical Report for 

 1883, page 145, 

 plate 28, fig. 1, 

 natural size; right 

 side view of a cast 

 of the interior of a 

 shell distorted by 

 pressure ; fig. 3, is 

 a view of the back 

 or hinge of the cast 

 The hind edges of 

 the two valves of 

 the shell are turned 

 up sharply so as to 

 give the hinge 

 margin the appear- 

 anceof a keel. 

 Species remarka- 

 ble for its long and 

 slender form ; the 

 largest specimens 

 not less than 8^ 

 inches long. XIII 

 — X F. Known to 

 be found in both 

 Lower and Upper 

 Coal Measures, 

 from Indiana to 

 Nebraska and in 

 Lower, Middle and 

 Upper Coal Meas- 

 ures of Indiana. — 

 Fig. 12, on page 

 plate 444 of the An. 

 Rt, 1885, of Penn. 

 Survey is added to 

 show how an im- 

 n.28 perfect cast of it- 



