136 SMITHSONIAX MISCELLANEOUS COLLECTIONS VOL. 64 



DESCRIPTION OF PLATE 13 



PAGE 



Collenia undosa Walcott. (See pi. 14) 113 



Fig. I. (Natural size.) Vertical polished section through a layer in 

 which numerous specimens are embedded. U. S. National 

 Museum, Catalogue No. 60707. 

 Fig. 2. (Natural size'.) Photograph of thin section of a subspherical 

 specimen, showing the original growth as a dome and then 

 a second growth that apparently occurred after the specimen 

 had been rolled over. U. S. National Museum, Catalogue 

 No. 60708. 

 The specimens represented by figs, i and 2 are from locality 

 400b: Algonkian: Spokane shales; 8 miles (12.8 km.) west of 

 White Sulphur Springs at forks of Birch Creek, Meagher County, 

 Montana. 



