246 SEAWEEDS 



enclosed within a common cystocarp wall, with a single 

 apical opening As has been said, the antheridia and 

 tetraspores are produced within similar conceptacles. 

 The tetrasporangia arise at the base of the cavity, and 

 either surround a central sterile bundle of filaments, 

 or they occur in groups, separated by a wall of 

 tissue from each other, and each with a separate 

 apical pore (Melobesict). 



BANGIACE.E. 



General Characters. The thallus consists of cell- 

 filaments (Bangia), or flat plates of one layer of cells 

 and of irregular outline. Male reproductive bodies 

 without cilia are produced within cells of the 

 thallus, and they fertilise female cells specially 

 distinguished from the thallus cells only by a short 

 lateral protuberance. Non-sexual reproduction is 

 effected by spores produced by the thallus cells, 

 sometimes singly, sometimes after division of the 

 parent cell. 



There has been so much discussion as to the 

 systematic position of the Bangiacece, and with so 

 uncertain a result, that the terminology of the repro- 

 ductive bodies is difficult of application. The claim 

 put forward for their inclusion among the Rhodo- 

 phycece does not appear to be fully established, while 

 at the same time there is no little difficulty in 

 assigning them a place among the Chlorophycccu. 



The Thallus. The main argument for the inclusion 

 of the Bangiacecc among the Rhodophycecc is derived 



