290 ALG& 



growth ; in these branches zoospores are formed ; conjugation between 

 them has not actually been observed. External organs of reproduction 

 known as ' conceptacles ' have also been described on several species 

 of Bryopsis, which have been conjectured to be true sexual organs, 

 whether male or female, but their true structure and functions are alto- 

 gether obscure. If, as is probable, some of the swarm-spores of Codium 



FIG. 258. ~ Halimeda. Tuna Lmx. a, natural size ; b, portion with zoosporanges ( x 50). 

 (After Derbes et Solier.) 



and Bryopsis are in reality conjugating zoogametes, this would bring 

 these two families into close relationship to the Botrydiaceae ; and this 

 is probably the nearest affinity of the latter group. Spongocladia 

 (Aresch.), described >by Zanardini as belonging to the Siphoneae, appears 

 to be a genus more nearly allied to Cladophora, in which the filaments 

 are remarkably infested with sponge-spicules. 



LITERATURE. 



(Dasycladaceo: and Siphonocladacea. ) 



Nageli In Zeitschr. wiss. Bot. , 1844. 



Derbes & Solier Ann. Sc. Nat. (Bot.), 1850, p. 240. 



