l86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



Family (undetermined) 

 HURDIA, new genus 



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



Genotype. — Hurdia victoria, 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 Hurd, the name of a mountain 

 northeast of Leanchoil on the Canadian Pacific Railway, British 

 Columbia, Canada. 



HURDIA VICTORIA, new species 



Plate 32, fig. 9 



Of this species only the valves of the carapace are known. The 

 illustration (pi. 32. fig. 9) shows the natural size and proportion of 

 a right valve, A larger specimen has a length of 13.5 cm. 



The test was quite thin and readily compressed and distorted, 

 which causes considerable variation in the outlines of the valve. 



A faintly outlined reticulation of the surface is shown on several 

 specimens. 



The only nearly related form known to me is Hurdia triangulata. 



Formation and locality. — Middle Cambrian: (35k) Burgess shale 

 member of the Stephen formation, on the west slope of the ridge 

 between Mount Field and Wapta Peak, one mile (1.6 km.) northeast 

 of Burgess Pass, above Field, British Columbia. 



HURDIA TRIANGULATA, new species 



Plate 34, fig. I 



The left valve illustrating this species is slightly distortq^ by com- 

 pression, but it outlines the average form. The largest specimen of a 

 single valve in the collection has a length of about 10 cm. with a depth 

 of 6 cm. 



This species differs from Hurdia victoria in having a valve propor- 

 tionately shorter and deeper. 



Formation and locality. — Middle Cambrian: (35k) Burgess shale 

 member of the Stephen formation, on the west slope of the ridge 



