ECTOCARPALES 



H5 



else to the adult thallus once more. By analogy with other species 

 the dwarf plantlets with the plurilocular sporangia may be regarded 

 as haploid gametophytes. 



Elachistaceae : Elachista {elachistos, very small). Fig. 98. 



Church (1920) regarded this genus as being explicable morpho- 

 logically on the cable type of construction, although it must be 



Fig. 98. Elachista fucicola. A, plants on Fucus vesiculosus ( x 0-36). B, single 

 plant in section showing penetrating base, crowded sporangia, short paraphyses 

 and long assimilators. C, unilocular sporangia ( x 120). D, plurilocular sporangia 

 at base of assimilation thread ( x 220). (A-C, after Taylor; D, after Kylin.) 



regarded as a degenerate type in which the true structure is only 

 seen in the sporeling. This possesses a horizontal portion from 

 which a number of erect filaments arise, so that in the early stage it 

 is comparable morphologically to Eudesme. In the older plant the 

 erect filaments have developed to form a cushion composed of 

 densely branched filaments matted together and only becoming 

 free at the surface. The various species are epiphytic on other algae, 

 Elachista fucicola being especially abundant on species of Fucus. 

 The pluri- and unilocular sporangia, together with the long hairs, 



CSA 



10 



