232 
Lilian Lyle. 
ramosum. The dorsiventralism in this case, being due to certain 
conditions of growth, arises only in the initial stages of the plant, 
but may persist throughout its life cycle. 
The procumbent form of N. ramosum Batt. grows on the 
stipes of Laminaria Cloustoni and on Lithothamnion polymorphum, 
where it adheres to the rough surfaces, afterwards sending up 
Tetrasporanges of N. ramosum. Fig. 3. Thallus of N. ramosum f. reptans. 
All figures half nat. size. 
erect shoots, Figs. 1, 2, The under surfaces of the dorsiventral 
portions are provided with the sucker-like rhizoidal processes, the 
suckers characteristic of N. reptans , Fig. 3, and, if detached, 
would be taken for fragments of the latter, Figs, la, lb. A 
