ety - 37 - - decay of individual samples of algae and by the radiochemical determinaone which showed that in January 1955 a large fraction of the total radio- activity in the algae Caulerpa and Halimeda was due to Cel44 and that none 137 “2gof it was due to Cs°”", which contributed most of the activity in land plants. Birds . Birds were collected at four islands of Rongelap and Ailinginae Atolls te : during the latter part of October 1955. Terns were taken at Kabelle and _Lebaredj Islands in Rongelap Atoll and at Enibuk Island in Ailinginae Atoll "and included threespecies: the fairy tern (Gygis alba), the noddy tern _(Anous stolidus), and the black-naped tern (Sterna sumatrana). Terns _ were not available at Rongelap Island but two species of shore birds were collected at this site, including two ruddy turnstones (Arenaria interprés) . and a reef heron (Demigretta sacra sacra). en_Specimens taken at Kabelle and Labaredj were treated as northern tollbirds and as one group. Those birds from the southern island of _Rongelap_ as well as those from Enibuk Island ( Ailinginae Atoll) were con- “aidered toconstitute a southern group ° The birds of the southern group were further subdivided according to . their feeding habits into (1) the terns, which forage in the area of a few islands Within the atoll and feed principally on fish and (2) the shore birds, _ Which are migratory, any one bird remaining in the area of an atoll for UNIVERS TY Ae: UNIV. OF 0