Cambrian Rocks in Cape Breton. 447 



ginal furrows seen. Ocular tubercle a little way from 

 the hinge ; a broad obscure furrow behind it. An obs- 

 cure ridge runs from the posterior marginal curve to the 

 anterior middle of the valve, and thence curves up to the 

 lower end of the anterior- cardinal curve. 



Size. Length 5imm.; width 4imm.; depth of a valve 

 IJmm. 



Horizon and locality. Assise E. 3. f., Upper Etchemi- 

 nian at Dugald Brook, Scarce. 



Bradokona spectator, n. sp. PI. I. figs. 12 a to c?. 



This species is smaller than the preceding and has a 

 more finely pitted surface. The length and breadth of 

 the valves are about equal. Length of the hinge more 

 than half that of the valve (*) ; the anterior and posterior 

 cardinal curves are about equal in length ; both anterior 

 and posterior marginal curves are convex. The upper 

 part of the valve is most protuberent as in Schmidtella. 

 A sharp marginal furrov/ shows on some valves. The 

 ocular tubercle is prominent ; some examples show a short 

 thread-like ridge extending diagonally backward from the 

 tubercle ; this corresponds to a furrow on the inside of 

 the valve. 



Size. Length and breadth each 3i nun.; depth of a 

 valve 1 mm. 



Horizon and locality. In the dark brownish gray sandy 

 shale of Assise E. 1 d, Lower Etcheminian, at Boundary 

 Brook, Escasonie, Eather common. Also in Assises E. 1. 

 h. and E. 1. d. at Dugald Brook, Infrequent 

 Var. ACUTA, n. var. 



This is a large form more pointed below than the type. 

 Anterior marginal slope somewhat straightened. Ocular 

 tubercle distinct. 



Scidpture. Surface minutely punctate, and showing a 

 strong striation near the hinge. 



Size. Length and breadth each about 4 mm.; depth of a 

 valve 1 mm. 



