306 BULLETIN OF THE NATURAL HISTORY SOCIETY. 



SCHMIDTELLA (?) PERVETUS, n. Sp. PL IV. figs. 3« to C. 



Only the right (?) valve known. It is moderately arched and 

 without furrows, and its greatest fulness is in the upper half. The 

 hinge margin, which is more than half of the length of the valve is 

 formed by an infolding of the edge, without a furrow. No marginal 

 fold was observed. 



Sculpture. — The surface is covered with minute pits closely placed 

 the raised spaces between the pits become so prominent on the lower 

 part of the valve that the surface seems tuberculated ; towards the 

 lower and the posterior (?) edges, these tubercles are arranged in rows 

 so that there the valve seems covered with obscure ridges, parallel to 

 the margin ; at the opposite side of the valve, toward the hinge, the 

 pits become very fine, and the surface of the valve has a shining 

 appearance. 



Size. — Length, 3 mm. Width, 2|- mm. 



This species differs from S. cambrica of the Protolenus Zone in 

 the less protuberent centre of the valve, and the narrower and 

 straighter infolded border of the hinge line. The marginal fold also is 

 more distinct in S. cambrica which does not have the concentric mar- 

 ginal ridges of this species. 



SCHMIDTELLA, ACUTA, n. Sp. PI IV., figs. 4 a. C. 



Valve 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. Valve 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, and towards the hinge the arching of the valve turns 

 suddenly in towards the cardinal line. 



Sculpture. — The surface is smooth, somewhat shining, and covered 

 with minute pits or granulations, uniformely distributed. 



Size. — Length, 2^ mm. Width, 2 mm. 



This species, by its smooth surface and pointed form recalls the 

 genus Beyrichona of the Protolenus Fauna, but it has not the flattened 

 area near the hinge that marks that genus, and is more flattened in 

 lower part of the valve. 



From S. pervetus this species is distinguished by its finer ornamen- 

 tation and pointed lower margin ; and from S. cambrica by its 



