AECD-3446 -94- LAND VERTEBRATES ENIWETOK by Frank G. Lowman RATS Rats of the concaler group, Rattus exulans (Peale, 1848), were collected ; at Eniwetok Atoll on Biijiri and Engebi Islands. Although this species has the generic nameas the "Old World"rats, it is probably not congeneric with them, R, exulans differs from the Norway and Black rats by having a shorter head agg. body, a difference in the mammaeformula, and different coloration ana texture of the pelage. R. exulans differs from the concolor rats of the Malay Archipels and the Hawaiian rat in having a relatively longertail. The rats were caught in tin can traps. These were made by mounting . ’ mousetrap in the open end of a tin can and attaching a lid to the trap jaw in such a manner that the lid springs shut when tripped by the animal. It is not possible to greatly alter the sensitivity of this device, and as a result, a greater number hermit crabs and crickets were caught than rats oe The traps were set near the openings of the rat burrows or in the runway which were usually situated in medium to dense growths of morning glories (Ipomoea grandiflora) and sandbur (Cenchrus echinatus). In areas where there ss were no plants, R. exulans was not found. The diet of this rat consists mainly of insects and grass seeds. Coconst meat and pandanus fruit are eaten when available. breakfast foods were used for bait in the traps. Oatmeal and "Post Toasties The use of bacon or other grosses’: foods for bait was not successful. The specimenscollected for ashing were quick-frozen in a deep-frees® unit; others were killed by decapitation and the tissues fixed in Bouin's fixativer After fixation, the tissues were washed in 50 per cent alcohol and preserved in" 70 per cent alcohol. In preliminary histological examinations of the liver. ste