104 BOTANICAL GAZETTE [ FEBRUARY 
dissepiments, coarsely granulate protoplasm, and forming a reddish lime 
incrusted stratum on wet rocks. Inthe morphological characters of the fila- 
ment, S. rupicola approaches S. fenicillata, but is distinguished from it by 
the entirely different habit. 
The plants described in this paper as inhabiting the limestone : 
crust were collected and studied at intervals during a period of 
two years. I wish to thank Professor MacMillan for the help 
he has given me in the work. 
BOTANICAL LABORATORY. 
UNIVERSITY OF Minnesota. 
EXPLANATION OF PLATES VII-IX. 
PLATE VII. ‘ 
Photograph of deposit on one of the planks from the southwest side of 
e tank. The crust is made up of the Dichothrix and the two Lyngbyas. 
PLATE VIII. 
Photograph of deposit on a plank from another side of the tank showing 
PLATE up 2. 
Fic. ‘ Filament and pseudobranch of Dichothrix calcarea. XB 
eRe fe FIG. 2. Young filament of the same. a 
ee oo Fre. 3 a. of branches of the same. : i 
