1918] ELMORE—DIATOMS 187 
These analyses show about 1 per cent of solids in the lake, or 
about one-third of the amount in ocean water. This comparatively 
rapid increase in salinity has produced a corresponding change in 
the diatoms of the lake, as well as in all the other organisms that 
it contains. We have no knowledge of what diatoms were in the 
lake when the water was fresh, but we can safely assume that they 
- were all of species commonly found in fresh water elsewhere, per- 
haps the same as in Court Lake, a fresh-water lake which was 
formerly a part of Devils Lake. 
In my work I identified 56 species of diatoms in the lake. Of 
these, 25, as reported elsewhere, are genuine fresh-water species; 
20 are species that are found in either fresh or brackish water; 
3 are in brackish water only; 2 are reported as being found in fresh, 
brackish, or salt water; 2 in brackish or salt water; and 4 as marine 
only. It is possible that when the water in the lake was fresh 50 
of these species, that is, all but the 4 marine ones and the 2 that are 
brackish or marine, were living in it; however, this is not likely. 
It is probable that there was then a much larger proportion of 
fresh-water species, as there usually is in fresh water, and fewer 
of those of varied habitat. As the water became more saline, 
however, diatoms adapted to either fresh or brackish water gained 
a foothold, then those adapted to either brackish or salt water, 
and finally the 4 marine species. One of these marine species, 
Chaetoceros elmorei Boyer, classed as marine because the genus is 
a marine one, was identified by C. S. Boyer as a new species. It 
is not likely, however, that it originated in this lake, and it is 
probably to be found elsewhere. 
The importation of marine species so far inland is easily 
accounted for. It would be perfectly possible for them to be 
carried in the air, but adhering to migratory birds is a much more 
probable explanation. 
The 25 species of fresh-water diatoms present the greatest 
anomaly. There is nothing in their appearance to indicate that 
they have been in any way modified by their changed environment. 
There are several smaller lakes in the vicinity of Devils Lake 
which were formerly part of the main lake, but have been separated 
from it by the lowering of the water. The analysis of the water 
