448 Canadian Record of Science. 



Horizon and locality. Assise E. 1. b., Lower Etcheminian, 

 at Dugald Brook, Infrequent. 



A small example, supposed to be the young of this form 

 is narrower, more acutely pointed below, and with straight- 

 er anterior and posterior marginal curve, was found in 

 Assise E. 1 d. at Boundary Brook 



Mutation spinosa, n. mut. PI. I. figs. 13 a and l. 



Wide below the cardinal curves. Anterior marginal 

 curve straightened. A sharp marginal furrow all around 

 except at the hinge. 



The ocular tubercle is distinct and there are spines at 

 the ends of the cardinal curves, except at the lower end of 

 the posterior curve. 



Scidj^ticre. The surface is minutely punctate ; on the post- 

 erior slope of the valves and on a band descending back- 

 ward from the ocular tubercle, the pits merge into inter- 

 rupted strise, divided by inosculating ridges. 



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

 valve 1^ mm. 



Horizon and locality. An entire carapace in the Assise 

 E. 1. c, Lower Etcheminian, at Dugald Brook, Scarce. 



Mutation ^quata, n. mut. PI. I. figs. 14 a and h. 



Anterior and posterior sides nearly equal. The form is 

 oval, and is wide below the cardinal curves, which are 

 long. Anterior as well as posterior marginal curve regu- 

 larly arched. 



Scidpture. The surface has been corroded, but shows 

 traces of a minute pitting. 



Size. Length and breadth each 3f mm ; depth of a valve 

 1 mm. 



Horizon and locality. In Assise E. 3. d. Upper Etchemi- 

 nian Fauna, at Dugald Brook, Eare. 



Bradoeona observator, n. sp. PI. I. figs. 15 a to c. 



A small species of the same general form as the preced- 



