145 
18th of March, among these Tetraspora and Chlamydomonas 
in the Descalabrado fae and near the bank plenty of Cepha- 
leuros on the leaves of a tree. 
n Coamo Springs eae places were visited where I had 
ee ge in the beginning of January, as for instance 5 km. 
above the town of Coamo. Several changes had taken place in 
the alga-vegetation. Pithophora existed with akinetes, Spiro- 
a ain. 
similar condition showed itself in the 1 reservoirs at Rio 
Piedras, whic visited anew on the twenty-third of March. 
he alga-vegetation had changed pease since my former 
visit in the latter part of December; g stages appeared, 
certain species which at my first visit were penn had 
disappeared or become rare > and new species had ap, 
The last 
clonium, which cover the surface unless this is already occupied 
by lichens or mosse: 
If one should, in ae characterize Porto Rico’s vegetation 
of fi algae, one could call it the Land of Aerophilous 
cupied by — pee is this the case in the northern 
pacing: alga-vegetation in the few fresh-water lakes and 
s on the island, while its many brooks and rivers are com- 
a, poor in alga 
It is especially the iiss that are predominant, while 
the Chlorophyceae occupy a less prominent place, and the 
