EOTANY. 
The Fresh-water Algse of the Plains.— North-west of Thed- 
ford, Thomas Co., Nebraska, in the valley of the Middle Loup river, 
are quite a number of small stagnant ponds. They are chiefly por- 
tions of the river, cut off by the railroad which runs up the valley, or 
excavations along the track filled by rain drainage. On the 7th of 
August, 1889, I stopped here a day for the purpose of collecting algae. 
The " Sand Hill region " of Nebraska is not one to which one would 
naturally turn for collecting algae, but the list given below, which is 
the result of our day's work, shows it to contain an interesting algae 
flora. 
The ponds are shallow (2 to 8 in. deep), and have usually a firm, 
solid bottom, so that one may easily wade around in searching for 
specimens. The w^ater is slightly alkaline. The edges of the ponds 
are usually lined with rank growths of various sedges and grasses, with, 
frequently, patches of the common arrow-head {Sagitfarm variabilis, 
Engelm). One pond was noticeably lined by a thrifty growth of the 
rare grass Catabrosa aqiiatica (L.) Beauv. It extended into the pond 
for some distance, to where the water was nearly a foot deep. Quan- 
tities of Potemogcton and Zanichellia palustris L. grow from the bot- 
toms of the ponds, and are frequently mixed with several species of 
Chara. In some of the ponds I collected also the beautiful Bladder- 
^vort, Utricularia vulgaris L. Its clusters of bright >ellow flowers, 
here and there extending above the surface of the water, had a 
pleasing effect. At the edge of one pond I discovered also the little 
Bladderwort, Utricularia minor L. I notice . that this commonly 
extends out a foot or so from the water, on the damp or wet bank, 
around the roots of sedges, etc. The three Duckweeds, Lemna minor 
L., Lanna trisuka L., and Spirodela polyrrhiza (L.) Schleid., are 
common in almost every pond. The liverwort. Riccia fluitans L. also 
The species of Algas proper collected were as follows; — 
Mcrismopedia glaiica Naeg. Not apparently v 
n the eastern part of the State I have found it free 
Merismopedia violacea (Breb.) Kutz. Quite 
iolet or purplish slimy masses, which sometimes 
