. Fresh-water biology. Freshwater biology. Van Heurck and West include Orthosira under Melosira, while many others make a separate genus. The Orthosira forms are found in the same localities as Melosira but, are much less C abundant. Fig. 70. Orthosira orichalcea W. Smith. X 600. (Original.) 5 (2) Cells single, disc-shaped, not forming filaments; valves flat, convex, or undulating, mostly with radial rows of punctulations. Family Coscinodiscaceae . 6 6 (7, 8) Valves circular or nearly so, with radiating rows of dots or areola- tions, the disc with a distinct edge, usually bearing a circle of i
. Fresh-water biology. Freshwater biology. Van Heurck and West include Orthosira under Melosira, while many others make a separate genus. The Orthosira forms are found in the same localities as Melosira but, are much less C abundant. Fig. 70. Orthosira orichalcea W. Smith. X 600. (Original.) 5 (2) Cells single, disc-shaped, not forming filaments; valves flat, convex, or undulating, mostly with radial rows of punctulations. Family Coscinodiscaceae . 6 6 (7, 8) Valves circular or nearly so, with radiating rows of dots or areola- tions, the disc with a distinct edge, usually bearing a circle of inconspicuous submarginal spines. Coscinodiscus Ehrenberg. The number of species of Coscinodiscus is very large, mostly marine, although some occur in fresh water with other similar centric forms. Fig. 71. Coscinodiscus apicutatus Ehrenberg. X330. (After WoUe.) 7 (6, 8) Valves circular, showing a central smooth or punctate area, and an outer margin of radiating striations. Girdle view with undulating ends Cyclotella Kiitzing. The cells are disc-shaped and are distinguished from other disc- shaped forms principally by the smooth or punctate center and the undulating ends. It is found commonly in the plankton. Fig. 72. Cyclotella compta KUtzing var. a^nis Grun. a. Valve side; b, girdle side. X 408. (After SchUtt and van Heurck-Grunow.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ward, Henry Baldwin, 1865-1945; Whipple, George Chandler, 1866-1924. joint author. New York, John Wiley & sons, inc. ; [etc. ,etc. ]
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
