Because of this excessive amount of quenching, total radioactivity is estimated only by comparing Eniwetok and California crab samples of 416 to 616 mg in weight. On this basis one can get estimates that suggest that the Eniwetok crabs contain an excess of 3 to 33 counts per minute per gram of tissue. This figure could easily be doubled or quadrupled because of quenching and also to allow for a safety factor. One specimen (No. 4) of Eniwetok crab skeleton gave the same count rate as California crab tissue. Since this specimen had three times as much tissue and it quenched a "Sc, standard by over 90% it is assumed that the sample is truly radioactive. All other Eniwetok samples gave count rates higher (57.7-78.6 cpm) than California crab samples regardless of weights which were both less and more than the California crab tissue specimens. See Table |. The maximum of 33 (x2-4) counts per minute per gram dry weight obtained is about 100 times less than the figures of 10° per gram of wet weights given for Cenobita crab specimens collected at Eniwetok in 1955. Science 14:18-27). The difference may be due to species difference, time for dilution, and lecal collecting sights. from Bell (See Held, H.E., 1960, Pacific The Cenobita specimens came islet in the north part of the atoll, Birgus from Glenn in the south. Analysis of the spectral distribution of the counts (see the 5 pages of graphs following) gives further evidence of the excess of radioactivity of the Eniwetok crabs compared to California crabs. One can compare samples 1, 3, 5, 7, 8, 9, 10, from Eniwetok with samples 11 and 12 from California for the skeleton. Also samples 2 and 6 with sample 11] respectively for muscle tissue which shows that muscle tissue of the Eniwetok crabs also contains above normal levels of radionucleides. The spectral distribution for scintillation vials that are blank and vials containing As Ca, 60 Co, and 3 H is also given for comparison. 90 Sr, 137 Cs, This indicates that the increase in radioactivity of the Eniwetok crabs is due to medium to low energy nucleides. However, it is suspected that the high degree of quenching evident may have shifted the peaks of the crab specimens to the right and probably the radioactivity present is due to 305, and 1376 as found in residual radioactivity reported by other researchers. 1960, Pacific Science, 14:18-27). (See Held, H.E., The habit of the coconut crabs of eating their exuviae (molted shell) would favor the perpetuation of radioactivity °