NO. 6 MIDDLE CAMBRIAN BRANCHIOPODA, ETC. l8l 



Thorax with 8 segments bearing more or less foliaceous jointed 

 appendages that carry a small scale-like exopodite, or it may be an 

 epipodite. 



Eyes pedunculated. 



One genus, Waptia, is referred to this family. 



WAPTIA, new genus 



The generic description is included with that of the type species. 



Genotype. — Waptia Heldensis, new species. 



Stratigraphic range. — The stratigraphic range is limited to a band 

 of dark siliceous shale about 4 feet in thickness forming a part of the 

 Burgess shale member of the Stephen formation. 



Geographic distribution.- — On the slope of the ridge between Wapta 

 Peak and Mount Field, north of Burgess Pass, and about 3800 feet 

 above Field on the line of the Canadian Pacific Railway, British 

 Columbia, Canada. 



Generic name derived from Mount Wapta, a mountain above the 

 fossil bed in which the type specimens of the genus and species were 

 found. 



WAPTIA FIELDENSIS, new species 

 Plate 27, figs. 4 and 5 



Carapace about one-third the length of the body. Seen from the 

 side it is broadly oval in outline with the upper side slightly curved. 

 From above, when flattened out, it is narrowed toward the front and 

 projects into broad lobes separated by a forward curving toward the 

 median line. In figure 5 the carapace has been pushed forward and 

 turned over so as nearly to reverse its true position. In figure 4 it 

 has been compressed laterally so as to give the posterior parts a 

 wing-like appearance. The test was so delicate that only a few speci- 

 mens show even approximately the original outlines. 



Body long and slender. It is divided into a head, trunk or thorax, 

 abdomen, and tail. 



The head cannot be clearly described as it is largely concealed by 

 the carapace. The presence of appendages indicates that 5 segments 

 are combined to form it. 



The trunk or body is formed of eight short segments, nearly equal 

 in size, each bearing a pair of appendages. 



The abdomen has six long, sharply defined segments with short 

 spines on the posterior margin. The caudal rami are expanded into 

 rather broad lobes that overlap slightly so as to form a strong caudal 

 fin. 



