SUBCLASS II 



EUCEUSTACEA— BRANCHIOPODA 



'33 



Riheiria 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 tlie eaiiy Ordovician of Europe and America, and are doubtfully 

 assigned to a position among tlie Apodidae. 



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

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

 some species of Apus having a length of 70 mm. The under-mentioned Cambrian 

 Notostracans are placed in separate families by Walcott. 



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

 Cambrian ; British Columbia. 



Änomalocaris Whiteaves. This name has been applied to bodies from the 



Fig. 1415. 



Narctoia compacta Walcott. Middle Cambrian ; 

 British Columbia. Dorsal view, x 2/,. 



Fio. 1416. 



Waptia fieldensis Wal- 

 cott. Middle Cambrian ; 

 British Columbia. Dorsal 

 view of flattened specimen, 

 X Vi- 



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

 of a Branchiopod, 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 

 affin ities 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. 



Orders. CONCHOSTRACA Sars. 



Carapace hivalved, enclodng the whole hody ; antennae well developed, hiramous^ 

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

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

 Furcal rami claw-like. 



