169 



of the valve. No ocular tubercle could be detected, but at what appears 

 to be the posterior upper angle of the valve is a small tubercle. The 

 anterior cardinal curve is short and nearly in the direction of the hinge ; 

 the posterior is wanting. The anterior marginal curve is long and strong- 

 ly arched ; the posterior is shorter and less arched, abruptly rounded 

 below, and at a right angle with the hinge line. The valve is highest at 

 the middle, gently arched toward the hinge, and to the lower margin of 

 the valve, and more abruptly towards the anterior margin. A faint ridge 

 or swelling runs along the back of the valve near the margin. Lower 

 angle of the valve bluntly rounded. Traces of a narrow marginal fold 

 are preserved in some places. 



Sculpture. The surface is corroded, and only in a few places can a fine 

 punctation be seen. 



Size. Length, 6 mm. ; width, 6 mm. ; depth, 1 mm. 



Horizon and Locality. In a fine gray shale, containing grains and 

 lumps of calcium phosphate, included in the Coldbrook volcanic rocks at 

 Dugald brook, Escasonie, N.S. Scarce. 



This ancient Ostracod has the outline of a Beyrichona, but there is no 

 flattened cardinal area of the valve, nor any trace of the deep muscle-pit 

 of that genus. It is separated from Bradoria by the absence of ocular 

 tubercle and posterior cardinal slope. It is provisionally placed in Esca- 

 sona, though lacking the high elevation of the cardinal third of the valve, 

 peculiar to the other species of that genus. 



INDIANA.* 



Can. Rec. Sci., vol. VIII., 1902, p. 460. 



Two forms of Ostracods of the Etcheminian Fauna differ from any of Genus 

 the preceeding by their marked oval form and do not seem to fall into 

 any of the later genera. The author has heretofore referred resembling 

 forms to Aparchites and Prirnitia, but omitting from consideration the 

 large size of most of the Basal Cambrian species, they also have usually a 

 well developed ocular tubercle, or the rudiments of one. 



In a decorticated example there is a faint muscle mark, where the mus- 

 cle scar is placed in Bradoria and Bradorona, but it projects less toward 

 the middle of the valve than in those. 



The enus consists of large to medium-sized Ostracods, oval or ovate 



O 



in form, the outline somewhat straighten td along the hinge,somewhat 

 sharply rounded at the anterior end, more broadly at the posterior. A 

 ventral angle is scarce traceable, and the greatest fulness is in the post- 



* Named for the Indian brook, on the branches of which these fossils were found. 



