Page:An introduction to physiological and systematical botany (1st edition).djvu/527

 Rh for his apothecium, pedicellus for his bacillum or podetium, and semina for his sporæ, because I see no improvement in the change. When this or any other writer strikes out new ideas, and discriminates parts hitherto mistaken or unknown, we thankfully receive from him new terms to express his discoveries. Thus the cyphella of Acharius is a peculiar sort of pit or pore on the under side of the frond in that section of Lichens called Sticta, see ''Engl. Bot. t. 1103, 1104; his lirellæ are the black letter-like receptacles of the genus Opegrapha, t. 1753—1756; his tricæ the analogous parts, resembling a coiled horse-hair, in Gyrophora, the Umbilicaria of Hoffmann, t.'' 522. These terms are necessary and instructive, and are chosen with that accuracy and taste for which Dr. Acharius is conspicuous.

The aquatic or submersed Algæ form a distinct and peculiar tribe. Some of these abound in fresh water, others in the sea, whence the latter are commonly denominated sea-weeds. The chief genera are Ulva, t. 419, 420, 1276, well defined by