NO. 6 MIDDLE CAMBRIAN BRANCHIOPODA, ETC. 175 



Formation and locality.- — Middle Cambrian: f-^ — j Burgess shale 



member of the Stephen formation (about 75 feet above the phyllopod 

 bed near the base of the shale) , on the west slope of the ridge between 

 Mount Field and Wapta Peak, one mile (1.6 km.) northeast of Bur- 

 gess Pass, above Field, British Columbia. 



Order NOTOSTRACA Caiman^ 

 NARAOIDiE, new family 



Carapace large, with hepatic caeca in anterior portion ; eyes pedun- 

 culate. Head with 5 ? pairs of appendages. Thorax with 17 to 19 

 segments. Abdomen with 2 to 3 segments. Thoracic appendages 

 leg-like, with setiferous fringes and probably gills attached to the 

 basal joints. 



One genus, Naraoia. 



NARAOIA, new genus 



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



Genotype. — Naraoia compacta, 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. 



The generic name is derived from Narao, the name of a group of 

 small lakes in Cataract Brook canyon, above Hector on the Canadian 

 Pacific Railway, British Columbia, Canada. 



NARAOIA COMPACTA, new species 



Plate 28, figs. 3 and 4 

 General outline of dorsal carapace elongate oval. It is divided into 

 two subequal parts forming the cephalic carapace and a posterior or 

 thoracic carapace. When flattened on the shale and not distorted, 

 the two parts are subequal in size and outline. The anterior part is 

 distorted in figure 4, but the posterior part has nearly the natural out- 

 line of a specimen when flattened out. It has a slight inward arching 

 at the median line where the abdomen passes from beneath it. The 



^ As defined in Lankester's Treatise on Zoology, London, 1909, Pt. 7, p. 53- 



