324 THALLOPHYTES 
It is now evident that among the Brown Algae there is more 
differentiation of plant body and more specialization in sexuality 
than among the Green Algae. Except in their lowest forms, they 
show no affinities with the Green Algae and consequently are 
supposed to have originated independently and probably from 
such organisms as gave rise to the Green Algae. Unlike the Green 
Algae they show no evidence of having led to higher forms. 
Red Algae (Rhodophyceae) 
These Algae are mainly marine forms, although some forms 
occur in streams. Besides the green they have a red pigment 
called phycoerythrin which determines their color. Some also 
Fic. 280. — A finely branched Red Alga. Natural size. 
have a blue pigment, phycocyanin. They are not so bulky as the 
Brown Algae, but they exceed them in number of species and are 
rouch more diversified in form. Some are mere filaments no 
larger than Vaucheria. They live mostly below low water mark 
and often at depths of more than 100 feet in clear waters. 
“The plant body, commonly only a few inches in length, is flat, 
thin, and flexible and usually much branched. Some kinds are 
finely branched, as the Sea Mosses noted also for their beautiful 
colors of red, violet, and purple (fig. 280). As in the Brown 
