379 



fairly high up on the branches of C. pohjspermam. Lastly, the 

 habit of C. scopu.loru.rn is very constant and easy of recognition - 

 it is ahvays small and never attains to the size of C. polyspermum, 

 and the colour also is different. 



The accompanying ligures (figs. 56, 57) show different parts of 

 the plant. The erect filaments start in a more or less'lprostrate 

 base (fig. 57) and from this spring numerous vigorous rhizoids by 



Fig. 56. Callithamnion scopulorum Ag. Portions of branches with tetraspores. Fig. a 50 : 1. Fig. b 75 : 1. 



means of which the plant attaches itself to the rocks. Such vigo- 

 rous rhizoids also spring from the long branches proceeding from 

 the basal part of the plant attaching these also in turn to the rocks 

 so that wiien they become in some way disengaged from the mother 

 plant they turn into independant piants, and this also accounts for 

 their densely tufted growth. In the lower part of the filaments the 

 cells are short, but those higher up are longer and generally bear 

 only short branches which proceed from the upper part of the 

 cells. These short branches are sometimes naked, but as a rule 



