Cambrian Rocks in Cape Breton. 443 



them. Perhaps the most notable is the way in which the 

 visual and muscular organs are crowded at the front end 

 of the hinge. This would exclude them from the great 

 family of the Leperditidte, Jones, in which the muscle scar 

 is near the middle of the valve, The lateral expansion of 

 the valves also is characterestic, and still more the way 

 in which many are pointed at the middle of the ventral 

 margin. 



We see no nearer relation in these species to the "zoe" 

 group of giants described by Barrande, than to the Leper- 

 ditidse ; these remind one more of the bivalve carapaces 

 of Phyllopod crustaceans. The Canadian forms, though 

 many are above the average size of the fossil Ostracoda, 

 are far inferior in this respect to Aristozoe and its allies. 



It seems to the writer that the position of the main 

 adductor muscle scar separates these species from all des- 

 cribed Ostracoda, and he would suggest for them the de- 

 signation Bracloriidae, taking as types the genera Beyri- 

 chona and Bradoria. Hipponicharion is widely diver- 

 gant from the others and in its strongly ridged surface 

 -simulates Beyrichia and may for the present be placed in 

 the family Beyrichida?. 



Leperditia ? ? EUGOSA, n, sp. PL I. fig. la to c. 



This species may prove to be of another genus when 

 more numerous examples are found. The single example 

 found does not seem to justify a final reference to any 

 described genus. 



Only the right valve is known and this is rather tiat, 

 and flattened toward the hinge and the posterior slope ; 

 its greatest convexity is in the middle and the lower third 

 The outline is broadly oval, with a hinge line half of the 

 length of the valve. The anterior and posterior cardinal 

 curves are long; the posterior marginal curve and the 

 lower side of the valve are both somewhat straightened, 

 and the anterior marginal curve strongly rounded. 



