S03 • PALiEOXTOLOGY OF NEW- YORK. 



Geological fo}'mations and localities. This species occurs in the Schoharie grit, 

 in Albany and Schoharie counties, usually of medium size and well marked cha- 

 racters, and sometimes attaining larger dimensions. It occurs iu the limestone of 

 the Upper Ilelderberg, in Albany and Schoharie counties, and at nearly all the 

 localities of that rock as far as the Niagara river ; particularly at Clarence and 

 "Williamsville in Eric county. It is found at several localities in Canada "West ; 

 also at the Falls of the Ohio and at Columbus and Millford, Ohio, and probably 

 at Sandusky aud other localities of the Corniferous limestone in the West. Some 

 large imperfect valves in the Hamilton shales of Central New- York may probably 

 be of this species. 



Meristclla scitula. 



PLATE XLVII. 



Mrypa tcitula : Hall, Geol. Report of the Fourth District New-York, p. 171, f. 1. 1843. 



Hot Mhyrit (?) scitula : Hall; Bilukqs in Canadian Journal (n. s.), No.uLvii, p. 278, f. 35 &. 86. 



18G0. 

 Ckarionella circe : Bilusgs, Canadian Jour, (iv s.), No. xxxviii, p. 273, f. 100. 1861. 

 Not Terebratula circe, Bakbande {Spirigera circe, D'OaniasY), Naturwissenschaftlidie Abhandl., 

 pa. 393, pi. 10, f. 6 (1857), which is apparently congeneric, and a true Meeistella. 



Shell ovate or ovate*spatulate, compressed towards the base. 



Ventral valve the more convex, sometimes gibbous above the middle, 

 depressed in the lower part ; umbo prominent, with the beak elevated 

 and incurved above the umbo of the opposite valve. The shell curves 

 gently to the base and baso-lateral margins, but becomes abruptly 

 incurved above the middle, and concave on each side for some distance 

 below the beak ; the proportions of breadth above are as six to five, or 

 seven to six. 



Dorsal valve depressed convex in the lower part, more convex and 

 somewhat gibbous above the middle ; beak small and rather prominent. 



Surface marked by fine concentric strite, which, from the usual partial 

 exfoliation of the shell, are often scarcely perceptible : more rarely 

 some remains of obsolete interrupted radiating striae are perceptible. 

 The shell, as it usually occurs, is smooth and glabrous. 

 This species has the usual features of others of the genus. It differs from 31. dot-is 



in being less gibbous, with a lesser arcuation of the ventral valve, the ujiper 



part less elongate and attenuate, and a less extensive flattening of the sides of tlio 



ibcll. 



