PH.EOPHYCE^E 



91 



similar habit of growth. Irregularly globular and 

 half-globular, corrugated forms of thallus with 

 hollow interior, like Leathesia, occur, and consist at the 

 most of vertical or oblique cell-rows, more or less 



Fio. 21. Leathcsia differ mis. a, plurilocular, and b, unilocular sporangia. 

 Highly magnified. 



branched, almost colourless within and giving rise 

 externally to the characteristic assimilative filaments. 

 In Myrionema, Microspongium, and allied genera, the 

 assimilative filaments spring from a basal cushion of 

 one or two layers of parenchymatous cells, or even of 



