173 



Some examples from the original bed show a valve highest in the middle, 

 and with a hinge-line half of the length of the valve. There are traces of 

 a narrow marginal fold. 



" This species differs from Bradoria rugulosa in its coarser ornamenta- 

 tion and in the broader curve of the lower margin. " From S. cambrica 

 of the Protolenus Fauna it differs in the less protuberant centre of the 

 valve and the narrower and the straighter infolded border at the hinge- 

 line. The marginal fold is also more distinct in S. cambrica, which does 

 not have the concentric marginal ridges of this species. 



Mutation CONCINNA, n. mut. 



Can. Rec. Sci. Montreal, 1902, p. 464. 



Highest part of the valve about two-fifths from the hinge ; evenly Mutation 



. . . concinna. 



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, 2J mm. ; width, 2 mm. ; depth of a valve, ^ mm. 



Horizon and locality. Assise E. 1 d., Lower Etcheminian, at 

 Boundary brook, Escasonie, N.S. Scarce. 



This mutation is smaller and rounder than the type. 



SCHMIDTELLA (T) ACUTA, PI. XIII, figs. 12 a to C. 



Schmidtella acuta, n. sp., Nat. Hist. Soc. N.B., Bull vol. iv. p. 206, pi. 



iv., figs. 4 a to c. 



Can. Rec. Sci. Montreal, p. 465. 



" Valves tumid. Hinge line somewhat more than half of the length Schmidtella (?) 

 of the valve, marked by a narrow fold and furrow that extends most of a( 

 its length. Yalves 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 ocu-lar tubercle. 



"Sculpture. The surface is smooth in appearance and somewhat shin- 

 ing, but under the lens is seen to be covered with minute pits or granula- 

 tions, uniformly distributed." 



Size. Length, 2| mm. ; width, 2 n m. ; depth, nearly 1 mm. 



