68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 13 



PAGE 



Laggania cambria Walcott 52 



Fig. I. Ventral view, natural size. m = mouth. U. S. National 

 Museum, Catalogue No. 57555- 



Mackensia costalis Walcott 55 



Fig. 2. A small individual showing the side view with the mouth. 

 Natural size. U. S. National Museurn, Catalogue No. 57556. 

 3. A fragment of a large specimen that may belong to this species. 

 Natural size. U. S. National Museum, Catalogue No. 57557- 



Louisella pedunculata Walcott 53 



Fig. 4. An individual flattened in the shale. X 2. The series of small 

 tube feet are flattened down on the surface, but show quite 

 clearly in a double row. U. S. National Museum, Catalogue 



No. 57558. 



All of the specimens illustrated on this plate are from locality (35k) 

 Middle Cambrian ; dark siliceous shales in the Burgess shale 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. 



