Date of this Version
Transactions of the American Microscopical Society, Vol. 33, No. 1 (Jan., 1914), pp.11-49
A dozen or more years ago the writer prepared a series of papers on these plants, which were published in volumes 21, 22 and 23 of these Transactions, and now it seems that time enough has elapsed to warrant another paper dealing with the same group, and including such revisions as are now made necessary because of our better knowledge of their structure, and the structure of the nearly related plants.