La Parguera, a fishing village in tile southern coast of Puerto Rico, is located between Guanica and Cabo Rojo. The region is characterized by a series of coral reefs which form two crescent-shaped arcs scattered over an area of some 80 miles. During the past years several reports as those of Allen (1957), Burkholder and Burkholder (1958), Burkholder, Burkholder and Rivero (1959), Odum, Burkholder and Rivero (1959), Margalef (1959), Goreau and Gorean 1960, and Burkholder and Burkholder (1960) have dealt with several aspects related to coral reefs, however, little attention has been given as to the distribution, taxonomy, and ecology of the marine algal flora of this area. It was with '[his idea in mind that this study was undertaken.