158 



Horizon and locality. Assise E. 1 c, Lower Etcheminian, at Dugald 

 brook ; scarce. 



Mutation 



magna 



described. 



Mutation 



major 



described. 



Mutation MAGNA, PI. XII figs. 1 1 a and b. 



Can. Rec. Sci., Montreal, 1902, Vol. VIII., p. 446. 



Valves rather tumid, hinge-line shorter than in the type, two-fifths of 

 the length of the valve ; ocular tubercle prominent, behind and around 

 it is a shallow furrow ; cardinal curves of the margin long. No marginal 

 furrow is visible. 



Sculpture. Surface pitted ; there are obscure anastomosing ridges 

 between the pits parallel to and near the margin ; a narrow obscure 

 band extends from ocular tubercle obliquely backward and downward. 



Size. Length, 5 mm. ; width, 4 mm. ; depth of a valve 1^ mm. 



Horizon and locality. Assise E. 2 b, Lower Etcheminian, at Dugald 

 brook ; scarce. 



Mutation MAJOR, PI. XII., figs. 10 a and b. 



Can. Rec. Sci. Montreal, 1902, Vol. VIII., p. 446. 



Valves rather tumid, hinge-line about three-fifths of the length of the 

 valve. Cardinal curves rounded ; no marginal furrows seen. Ocular 

 tubercle a little way from the hinge ; a broad obscure furrow behind it. 

 An obscure 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 5J mm. ; width 4 mm. ; depth of a valve 1 mm. 



Horizon and locality. Assise E. 3 f., Upper Etcheminian at Dugald 

 brook ; scarce. 



Bradorona 



spectator 



described. 



BRADORONA SPECTATOR. PI. XII., figs. 12 a to c?. 



Can. Rec. Sci., Montreal, 1902, Vol. VIII., p. 447. 



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 pos- 

 terior cardinal curves are about equal in length ; both anterior and pos- 

 terior marginal curves are convex. The upper part of the valve is most 

 protuberent as in Schmidtella. A sharp marginal furrow shows on some 

 valves. The ocular tubercle is prominent ; some examples show a short 



