Cambrian Rocks in Cape Breton. 465 



hinge ; evenly sloped to the margins, except that the 

 anterior side is somewhat more turgid than the posterior. 

 Hinge line about half of the length of the valve. A very 

 narrow fold runs around the margin. 



Sculpture. — Surface with a fine but distinct punctation 

 that develops anastomosing ridges near the margins. 



Size. — Length, 2\ mm. ; width, 2h mm. ; depth of a 

 valve, f mm. 



Horizon and Locality. — Assise E. 1 d., Lower Etchemin- 

 ian, at Boundary Brook, scarce. 



This mutation is smaller and rounder than the type. 



SCHMIDTELLA ACUTA, PI. II., figS. 12 ^<^ to C. 



Schmidtella acuta, n. sp., ISTat. Hist. Soc. N".B., Bull vol. iv. 

 p. 206, pi. iv., figs. 4 « to c. 



" Valves tumid. Hinge line somewhat more than half of 

 the length of the valve, marked by a narrow fold and 

 furrow that extends most of its length. Valves about as 

 wide as long, somewhat acutely pointed at the lower 

 margin. A narrow marginal fold extends along one side 

 of the valve to the pointed end. Greatest protuberance 

 of the valve in the upper half ; toward the hinge the curve 

 of the surface of the valve is turned somewhat abruptly 

 inward toward the cardinal line." 



This species has a small ocular tubercle. 



"Sculpture. — The surface is smooth in appearance and 

 somewhat shining, but under the lens is seen to be covered 

 with minute pits or granulations, uniformly distributed." 



Size. — Length, 2h mm. ; width, 2\ mm. ; depth, nearly 

 1 mm. 



Horizon and Locality. — In Assise E. 3 g and /, Upper 

 Etcheminian, at Dugald Brook. Frequent. 



The following are measurements of the valves of this 

 ■species : 



