4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 78 



fcion must be only provisional. Tentatively, therefore, we will refer 

 them to the order Conchostraca of the superorder Branchiopoda. 



In the table below we give our present idea of the classification of 

 the Conchostraca and of the Cambrian and allied genera of related 

 branchiopod Crustacea. 



CLASSIFICATION OF CAMBRIAN CONCHOSTRACA AND ALLIED 



GENERA 



Class CRUSTACEA 

 Subclass Eucrustracea 



Superorder BRANCHIOPODA Latreille (PHYLLOPODA, part) 

 Order ANOSTRACA Sars 



Opabinia, Leanchoilia, Yohoia, and Bidentia, all of Walcott and from 

 the Middle Cambrian of British Columbia. 



Order NOTOSTRACA Sars 



Protocaris Walcott; Lower Cambrian, Vermont. 



Ribeiria Sharpe and Ribeiriella Shubert and Waagen; Canadian and 



Early Ordovician of Europe and America. 

 Apus Latreille, Trias-Recent; Lepidurus Leach, Recent. 

 Burgessia Walcott; Middle Cambrian of British Columbia. 

 Isoxys Walcott; Cambrian. 

 Euchasma, Eopteria, and Ischyrina of Billings, and TechnophoruSy 



Miller; Canadian, Ordovician and Early Silurian, 



Order CONCHOSTRACA Sars 



Family BRADORIIDAE Matthew 



Bradoria Matthew (Bradorona Matthew); Lower and Middle Cam- 

 brian. 

 Walcoitella, new genus; Middle Cambrian. 



Family BEYRICHONIDAE, new family 



Beyrichona Matthew {Escasona Matthew); Lower and Middle Cam- 

 brian. 

 Sellula Wiman; Lower Cambrian, Sweden. 

 Aluta Matthew; Lower and Middle Cambrian. 

 Eremos Westergaard ; Canadian of Sweden. 

 Hipponicharion Matthew; Lower and Middle Cambrian. 

 Polyphyma Groom; Middle and Upper Cambrian. 



