THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[SECOND SERIES.] 

 No. 16. APRIL 1849. 



XXVI. — Note on Cystocoleus, a nerv genus of minute Plants. By 

 G. H. K. Thwaites, Lecturer on Botany and Vegetable Phy- 

 siology in the Bristol Medical School. 



[With a Plate.] 



Having recently been fortunate enough to meet with good spe- 

 cimens of the Byssus nigra, Eng. Bot., I have been enabled to 

 ascertain very satisfactorily its real structure, about which bo- 

 tanists appear hitherto to have been in much doubt. The struc- 

 ture of this plant is so peculiar as to render necessary its removal 

 from the genus Chroolepus, in which it now stands; and with 

 the sanction of my friend, the Rev. M. J. Berkeley, I propose 

 for it the new generic name of Cystocoleus, characterized as 

 follows. 



Cystocoleus. Plantse confervoidese, csespitosse ; filamentis arti- 

 culatis, cylindricis vel submoniliformibus, plus minusve ra- 

 mosis, vagina cellulosa continua singulatim inclusis. Chroo- 

 lepo affinis. 



Cystocoleus ebeneus. Fusco-nigei*, fragilis, parce ramosus. 



Conferva ebenea, Dillw. t. 101. 



Byssus nigra, E. B. t. 702 ! 



Chroolepus ebenea, Ag. Syst. Alg. p. 36 ; Harvey in Eng. Fl. 

 p. 381 ; Manual of British Alga, p. 190. 



It will be seen by the above generic characters that this plant 

 differs essentially from Chroolejms in having its filaments included 

 in a sheath composed of distinct cells, the membrane of which is 

 of a dark fuscous colour, and thus the internal filament can in 

 most cases be with difiiculty observed and examined. Occa- 

 sionally, however, the internal filament, which in structure and 

 character closely resembles the filaments of Chroolepus, protrudes 

 beyond the investing sheath, and may then be seen to consist of 

 oblong cells containing the peculiar reddish oily-looking endo- 



Ann.^Mag. N. Hist. Ser. 2. Vol. iii. 16 



