CRYPTOGAMIA. 377 



Thus Hedwig used the term sporangium for a seed- 

 vessel, pericarpiiim, in which the learner would 

 seek in vain for any distinction, or new idea. A 

 student might very justly complain if, in a science 

 necessarily so overburthened with words, he were 

 required to call the same part by a different name 

 in every different family. I would gladly therefore 

 retain the word frons in preference to the thallus 

 of Acharius, receptacidum for his apothecium, pedi- 

 cellus for his bacillum or podetlum, and scmina for 

 his sporce, 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 Stkta, see Engl. Bot. t. 1103, 1104; his 

 lirellce are the black letter-like receptacles of the 

 genus Opegrapha, t. 17^317.56; his trica the 

 analogous parts, resembling a coiled horse-hair, in 

 Gyrophora, the Umbilkaria 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 Alg<z form a distinct 

 and peculiar tribe. Some of these abound in fresh 

 water, others in the sea, whence the latter are com- 

 monly denominated sea-weeds. The chief genera 



