150 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



DESCRIPTION OF PLATE 20 



PAGE 



Newlandia frondosa Walcott. (See pis. 6, 7, 8) 105 



Fig. I. (X SCO-) Drawing of a plate of opal-like silica contain- 

 ing numerous slender tubes, some of which have irregularly 

 spaced partitions that have a distinct upper and lower sur- 

 face ihat probably indicates organic origin. This type is not 

 uncommon in material obtained by treating specimens of 

 ' this species with hydrochloric acid. U. S. National Mu- 

 seum, Catalogue No. 60719. 



Camasia spongiosa Walcott. (See pis. 9, 12) loi 



Fig. 2. (X 350.) Chain of cells as photographed and partly outlined. 



.The untouched micrograph is shown by tig. 4, where about 



half of the cells are in the focal plane. U. S. National 



Museum, Catalogue No. 60720. 



3. (About X 1400.) Outline sketch of the chain shown by tigs. 



2 and 4. 

 4- (X 350.) Micrograph of a portion of the fragment of opal- 

 like silica containing the chain of cells represented by 

 figs. 2 and 3. There are also present numerous minute 

 tubes similar to those illustrated by fig. i. 



5. 5« (X 350.) A group of seven supposedly round cells as they 



occur free from the matrix. Similar bodies occur in the 

 opal-like silica both singly and in groups. The untouched 

 micrograph is shown by fig. 5a. U. S. National Museum, 

 Catalogue No. 60722. 



6, 6a. (X 350-) Untouched micrograph of an irregular chain-like 



group of round cells that are free from the matrix. The 

 round cell-like bodies^ are outlined in fig. 6a as they appear 

 when examined under the microscope. U. S. National Mu- 

 seum, Catalogue No. 60723. 



Blue-green algce cells {Schizothrix ?) too 



Fig. 7. (About X 1200.) Outline drawing of a chain of cells obtained 

 by treating a recent Blue-green algal calcareous deposit 

 with hydrochloric acid. U. S. National Museum, Cata- 

 logue No. 60724. 

 8. (X 350.) Untouched photograph of a chain of cells obtained 

 by treating a Blue-green calcareous deposit from Green 

 Lake, Onondaga County, New York, with dilute hydro- 

 chloric acid. 

 8a. The same as fig. 8, with all the cells of the chain outlined. The 

 chain is free except where entangled with diatoms and bits 

 of opal-like silica. U. S. National Museum, Catalogue No. 

 60725. 

 The slides represented by figs. 7 and 8 were sent to me by Dr. 

 Charles A. Davis. The material containing the cells rep- 

 resented by fig. 7 is from North Lake, Waukesha County, 

 Wisconsin, 27 miles (43 km.) west-northwest of St. Paul, 

 and that by fig. 8 from Green Lake, Onondaga Count}-, New 

 York. 



