SUBCLASS II 



EUCRUSTACEA— BEANCHIOPODA 



733 



Ribeiria Sliarpe ; Ribeirella Shubert and Waagen. These names have been applied 

 to arched, univalved bodies with strong beaks, muscular scars and sub-cardinal ridge. 

 They occur in the early Ordovician of Europe and America, and are doubtfully 

 assigned to a position among the Ajjodidae. 



Apus Latreille. Trias to Recent. Lepidurus Leach. Recent. These genera, 

 included in the family Apodidae, comprise the largest known forms of Branchiopods, 

 some sjjecies of Ajms having a length of 70 mm. The imder-mentioned Cambrian 

 Notostracans are placed in separate families by Walcott. 



Naraoia (Fig. 1415), Burgessia and Waptia Walcott (Fig. 1416). Middle 

 Cambrian ; Britisli Columbia. 



Anomalocaris Whiteaves. This name has been aj^plied to bodies from the 



Pig. 1415. 



Naraoia covipacta Walcptt. Middle Cambrian ; 

 British Columbia. Dorsal view, x -/i. 



Fu.. 1410. 



Waptia Jieldensis Wal- 

 cott. Middle Cambrian ; 

 British Columbia. Dorsal 

 view of flattened specimen, 



Cambrian of British Columbia which have been comjjared to the segmented abdomen 

 of a Branchioj)od, each segment bearing a pair of lamellate appendages. Although 

 the objects abound where found, nothing is known of the carapace, nor is there any 

 evidence of the surface markings which characterise most Crustacean shields. Their 

 affinities are doubtful. 



Euchasma, Eopteria and Ischyrina Billings ; Technophorus Miller. These names 

 have been applied to remains from the Ordovician of North America, regarded by 

 their describers as Pelecypods, but undoubtedly of Crustacean nature. Their reference 

 to the Notostraca is uncertain. 



Order 3. CONCHOSTRACA Sars. 



Carapace hivalved, enclosing the tvhole body ; antennae ivell developed, biramotis, 

 natatory ; paired eyes sessile, coalescent. Body-limbs ten to twenty-seven pairs, of ivhich 

 none to sixteen are post-genital, and the first one or two in the male form clasping organs. 

 Fnrcal rami claw-like. 



