RHODOPHYCE^E, OR FLORIDE^E 239 



proceeding from the carpogonium successively ferti- 

 lises a number of auxiliary cells, each produced on its 

 own branch. After the conjugation of the ooblastema 

 filaments and auxiliary cells, the gonimoblast that 

 results is usually developed in the form of more or 

 less definite gonimolobes, almost all the cells of which 

 give rise to carpospores. The gonimoblast is in all 

 cases within the thallus tissue. The geographical 



a 



FIG. 81 a, fertilised carpogonium of Dudresnaya purpurifera ; b, ooblas- 

 tema filament attached to auxiliary cell in passage (D. coccinea) highly mag- 

 nified. (After Schinitz.) 



distribution is fairly general, and the British genera 

 are Gloiosiphmiia (Gloiosiplwnicce) ; Halymcnia and 

 Grateloupia (Grateloupiece) ; Dumontia, Dudresnaya, 

 and Dilsca (Dumontiece) ; and Calosiphonia, Schizy- 

 mcnia, and Furccllaria (Nemastomece). 



Rhizophyllidece. 



This family, also a small one of fairly general 

 distribution, is represented, in British seas by only 

 one genus, Polyidcs. The essential process of fertili- 



