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shores of the island were visited. My first and longest stop was 
made on the northern coast, at Santurce, a suburb of San Juan. 
The shore about San Juan offers a great variety of physical con- 
ditions, including coral reefs, surf-beaten littoral rocks, sand- 
beaches, nearly enclosed bays and lagoons, and mangrove 
swamps, and the region yields a correspondingly large number 
of species of sea-plants. I devoted four weeks to making collec- 
tions here and then came away without having seen all of the 
promising coast line within easy reach of the capital. A com- 
Fic. 18. The black mangrove (Avicennia), Ponce. 
parison of the marine flora of this locality with that of the parts 
of the island subsequently visited appeared to justify the spend- 
ing of a comparatively large proportion of my time at this point. 
The warmth of the sea-water about Porto Rico made possible a 
mode of collecting, which in former experiences, even in Florida, 
Bermuda and California, I have been able to employ only toa 
limited extent ; this may be briefly characterized as the ‘‘ bathing- 
suit method.” The sea is so warm that one may easily work in 
