133 
Piedras, both the large reservoir east of the Agricultural Station, 
from which San Juan receives its water supply, and the many 
smaller ones west of the station. On the walls of the former 
was a rich vegetation of end aa of Oedogonium, Rhizo- 
clonium, Lyngbya, and other gener: 
Amon ese were found a ee arge species of Rivularia, which 
formed sausage-like, sometimes slightly branched, masses o 
i cm. in diameter. Among th as 
mm 
Oo mn 
of the Agricultural Station, I found on the water plants thick 
threads of a probably new genus of algae, which externally 
on mbrane; it 
therefore, not any close relationship to Schizomeris na the 
resemblance is wholly superficial 
asins themselves, the alga-vegetation was very rich, 
consisting of species of th nera Oedogonium, Spirogyra, 
the 
similar localities, a rich vegetation of eee, Tveiaeeia 
and ae ies of Chroococcaceae. 
anuary 5th to the 15th, I stayed at Coamo Springs 
on outcrop; rocks, on walls and on the bark of trees. Amon 
the aerophilous Chlorophyceae may be mentioned a probably 
new genus, was found as a thick green covering on branches 
and roots in the dark forest behind the Bath; later I also found 
the same on limestone in a cave between Arecibo and Hatillo. 
This alga consists of much-branched rows of cells, which remind 
