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nated with alkali. At first attached to the substratum; finally rising 
and floating free in large, silky, yellowish masses. The individ- 
ual filaments are very sparingly branched, and ev masse look 
more like a Spirogyra than like a Cladophora. July to Septem- 
ber, but at its best in the middle of August. 
Cladophora crispata, Kg. Very abundant in shallow ponds 
and sloughs bordering the Prickly Pear Creek in the Prickly 
Pear Cafion. Floating in dark green, spongy, elastic masses of 
less or more curly, interwoven, and much-branched filaments, 
which spring out to their normal form after the water is squeezed 
from them, just as sponges do. Collected but once, and then in 
a luxuriant condition, April 19, 1887. 
Cladophora canalicularis, Kg. This common species was 
collected but once and then at the first rapids of the Great Falls 
of the Missouri River. The specimens had been cast ashore. 
They were about ten inches long, strict and rather brittle; the 
lower half was very dense and compact, being made up of short- 
er stems and branches arising from the hard, blackish, somewhat 
calcareous foot. Filaments pale yellow. October, 1886. 
Cladophora callicoma, Kg. Plentiful in the rapids of the 
Upper Missouri River, in the vicinity of the city of Great Falls. 
This is probably one of the most beautiful species of the genus ; 
but is usually so large and so copiously and intricately branched 
that a perfect specimen cannot be arranged on a standard-sized 
herbarium sheet. Forming in ropes three to ten feet long, grace- 
fully undulating in the flowing water and waving its beautiful 
lateral branches. See Wolle’s Fresh-Water Alge, p. 339. 
This species was first observed by us in August, 1884—when it 
was very abundant. Then a dam was built across the river just 
above the rapids and the disturbance caused the destruction of 
the plants. In 1886 it reappeared and although excellent speci- 
mens were collected as late as October, they did not compare 
with the luxurient growth of 1884. The plant is now regaining 
its vigor and may be found in good condition from July until the 
_ end of October. 
Cladophora glomerata, Kg. Common throughout the state. 
May be found in good condition from the middle of June till the _ 
end of September. The following varieties also occur: 
