1889.] The Vegetation of Hot Springs. 2>97 
found proving the abundance of algas in waters of 150'' Fahr. 
or below. The highest temperature at which these growths 
have been found is that observed by Professor Brewer at 
Pluton Creek, California, where algae were found at 200<* 
Fahr.' 
In the hot springs of Ischia no life was observed above 185** 
Fahr.,' and this appears to be the limiting temperature in the 
hot waters of the Yellowstone National Park. 
A comparison of the species found in hot springs shows that 
they are limited to a few groups. Although the true Confer- 
voidex and the Protococcoideae are represented in gather- 
ings from hot waters, the Oscillatorieae form the most charac- 
teristic vegetation of hot springs, species of Oscillaria and 
Hypheothrix being very common. Hypheothrix laminosa (a 
species variously known under a number of synonyms) has 
been found in New Zealand, Java, St. Paul, Camiguin, Ice- 
land (?) and the Yellowstone Park, being very common at the 
last locality. 
Desmids have been found in the hot waters of the Azores, 
three species of Pediastrum being described, and Corda figures 
and describes Desmids from the Carlsbad hot springs. The 
Diatomaceae do not appear to be very abundant in hot waters. 
Dr. Jas. Blake found a number of species at 140° Fahr. in the 
hot springs of Nevada, and nine species were found by Berkeley 
m the gatherings from Thibet. They are comparatively rare 
m the Yellowstone gatherings from hot water, but very abun- 
dant in the cooled waters from the springs. 
The examinations made by Mr. W. Archer of the gatherings 
of algae from the hot springs of the Azores show that certain 
species were identical with forms common in cold surface 
waters in Great Britain. Prof. W. G. Farlow, of Harvard, who 
is studying a series of specimens collected by the writer from 
the hot waters of the Yellowstone Park, informs me that here 
also cold water forms are found, but modified by their condi- 
tions of environment. It is hoped the material in Professor 
' Amer. Journ. Sci. (2.) XLVI., p. 31. 
' Sachs, in Flora. 1864. 
