The collecting sites from which isopods were obtained are located around the island (see p. 84). Concentrated collecting at several depths was done in the San Juan area at Boca de Cangrejos and at La Parguera where the Institute of Marine Biology is located. Many collections were made by washing a substrate sample in a bucket of formalin sea water soon after collection. Motile animals such as isopods fall to the bottom of the bucket. Substrate samples taken with SCUBA techniques were carefully placed in a plankton net and transferred to a surface vessel without loss of specimens en route. The substrate was broken up to obtain the burrowers and discarded and the remaining liquid filtered through a No. 00 mesh plankton net. The filtrate was preserved in 70% ethanol and the isopods were removed later with the aid of a binocular dissecting microscope and placed in vials in 70% ethanol. Isopods kept in formalin lose carbonate and are not easily identified. In all cases care was taken not to contaminate the environment with discarded formalin sea water.