148 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



DESCRIPTION OF PLATE 19 



PAGE 



Copperia tiibiformis Walcott no 



Fig. I. (Natural size.) Polished vertical section of a group of more 

 or less irregular tubes that form a layer 5.5 cm. thick. U. 

 S. National Museum, Catalogue No. 60716. 



2. (Natural size.) Surface of a group of tubes that were formed 



in a horizontal position. U. S. National Museum, Cata- 

 logue No. 60717. 



3. ( Natural size. ) View of a natural section of a layer 5 cm. 



in thickness in which the three lower layers of tubes are 

 fairly regular, while the upper layers show irregular growth. 

 U. S. National Museum, Catalogue No. 60718. 

 This form occurs in layers or tubes that are more or less parallel 

 to the bedding of the layer. 



The specimens represented by figs. 1-3 are from locality 400c: 

 Algonkian : Newland limestone; 8 miles (12.8 km.) west of White 

 Sulphur Springs, Meagher County, Montana. 



