I40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 21 



PAGE 



Whvaxia corrugata (Matthew) 123 



Fig. I. (X 2.) Portion of the dorsal surface with numerous scales 

 and five of the dorsal spines. U. S. National Museum, Cata- 

 logue No. 57633. 



2. (X 2.) Dorsal surface. The arrangement of the scales indi- 



cates that the anterior end was on the left side where the 

 outline is slightly incurved. U. S. National Museum, Cata- 

 logue No. 57634- 



3. (X 1-25.) A specimen crushed down so as to displace scales 



and spines. U. S. National Museum, Catalogue No. 57635. 



4. (Natural size.) Scattered scales and spines on surface of 



shale. U. S. National Museum, Catalogue No. 57636. 



Banff ia constricta Walcott 130 



Fig. 5. (Natural size.) A small specimen showing the two sections 

 of the body. U. S. National Museum, Catalogue No. 57637. 

 6. (Natural size.) Anterior section and constriction with a por- 

 tion of the posterior section. U. S. National Museum, Cat- 

 alogue No. 57638. 



PolUngeria grandis Walcott 125 



Fig. 7. (X2.) One of the larger scales. U. S. National Museum, 

 Catalogue No. 57639. 



8. (X2.) Scale furrowed by minute annelid. U. S. National 



Museum, Catalogue No. 57640. 



9. (X2.) Scales differing in form. U. S. National Museum, 



Catalogue No. 57641. 



All of the specimens illustrated on this plate are from locality (3Sk) 

 Middle Cambrian : dark siliceous shales in the 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. 



