FUCALES (HETEROGENERATAE) 



209 



borne on the periphery of the inflated nodes. Although eight ova 

 are originally formed in the megasporangia only four attain to 

 maturity, but in this genus, however, it is a case of degeneration of 

 eggs and not merely of nuclei. Another interesting feature of this 

 genus is its capacity to form and shed a cuticle that bears the im- 



Fig. 140. Honnosira Banksii. A, portion of plant ( x f ). B, longitudinal section 

 of apex of plant, a = air-filled space. C, transverse section of thallus at internode 

 ( X 1 50). D, longitudinal section of apex. E, transverse section of apex. F, cuticle 

 being shed (semi-diagrammatic). (A, C, after Getman; B, D, E, after Oltmanns; 

 F, original.) 



pressions of the cell outlines, this feature perhaps being of signi- 

 ficance v^^hen the problems concerning the Nematophyceae are 

 considered (cf. p. 277). The genus is monotypic, the single species, 

 H. Banksii, being confined to Australia and New Zealand where it 

 grows on rocks and in tide pools of the littoral belt in positions that 

 are always exposed to the spray. 



CSA 



14 



