In each area, automobiles and small boats, with operators, 

 were placed at the disposal of the investigators. Observations 

 and collections of specimens were made, the nature of the bottom 

 in each area was determined by probing with poles, and samples of 

 water, from which temperature, salinity, and pH were ascertained, 

 were taken just above the bottom. Salinity was calculated from 

 hydrometer readings of the density of the water, corrected to 17.6 C», 

 using Knudsen*s hydrographic tables (Knudsen, 1901), the pH was 

 measured oolorimetrically (using Thymol Blue as an indicator), the 

 results being expressed without correction for salt error* A bolt- 

 ing silk net of No. 20 mesh was towed at each station and samples 

 examined for plankton forms, including mollusoan larvae. Samples 

 of oysters were examined for condition and for the presence of 

 parasites} sections of the gills were examined in a fresh condition 

 microscopically. 



Acknowledgments are due to many Federal and insular Government 

 officials for courtesies and helpful cooperation, Mr. Derrickson 

 of the Departaent's Division of Territories and Island Possessions 

 made the initial arrangements. In Puerto Rico Mr. Roberto Sanchet 

 Villela, executive secretary to the Governorj Mr. Miguel Melendez 

 Ortiz, chief. Division of Fisheries and Wildlife Conservation and 

 Mr, Felix Inigo of the same divisioni and Mr, Abdom Peree of the 

 Puerto Rican Agricultural Development Corporation, arranged trans- 

 portation and provided every facility for the work. In the Virgin 

 Islands, Governor William H. Ifestie; Mr, Morris DeCastro, Government 

 Secretary; Messrs, George Simmons and Harry E, Taylor, administrators 

 for St. John and St, Croix, respectively; and Mr. Valdemar A, Hill, 

 former tax assessor, showed interested and effective cooperation in 

 every part of the work. Colonel Axel Oxholm, then special agent for 

 the TJ, S. Deparlment of Commerce, and particularly interested in the 

 development of new industries in the islands, gave us valuable infor- 

 mation and assistance. 



Survey of Areas 



Puerto Rico 



By use of a car furnished by the Government of Puerto Rico, 

 the principal coastal areas of the island were visited, Exeunination 

 of bay and lagoon waters was made by small boats and skiffs. The 

 survey also included Vieques Island, the largest and most populated of 

 the outlying islands of Puerto Eioo, some 11 miles off the southeast 

 coast. The plBces visited and considered are shown on the map of 

 Puerto Rico in Figure 1, Results of observations on water conditions 

 are grouped for convenience in Table 1, 



