379 
fairly high up oil the branches of C. polyspermum. Lastly, the 
habit of C. scopulorum is very constant and easy of recognition — 
it is always small and never attains to the size of C. poly sper mum, 
and the colour also is different. 
The accompanying figures (figs. 56, 57) show different parts of 
the plant. The erect filaments start in a more or less prostrate 
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 15 :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 when they become in some way disengaged from the mother 
plant they turn into independant plants, 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 
