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Amphipoda from depths of 0-30 m on hard bottoms are increased from about 40 to about 120 species, including 59 new species and 9 new genera and subgenera. About half of the species is endemic. Nearly 70 percent of the faunule has come from archipelagoes to the southwest of Hawaii, but only 15 percent of the faunule is of tropicopolitan character. About 20 percent of the fauna has affinities with cool waters of the North Pacific. This is the first significant record of cool-water species of any marine group in Hawaii. Most of these species have a tubicolous ecology, suggesting that nestlers are less successful in completing the long journey from the cool waters of northern continents. All but three species with cool-water affinities have diverged specifically from their mainland ancestors and at least two require erection of new genera to describe their divergence. Other endemic genera of Hawaii have low affinities with tropical Pacific faunas and have affinities with places like Antarctica, the Caribbean Sea, and warm-temperate Australia. The tropical component of Hawaiian Gammaridea is not impoverished by a priori standards of diversity. Few elements expected to occur in Hawaii are missing. No evidence of interisland adaptive radiation has been observed, but several pairs and triads of species with sibling affinities are described as a result of successive waves of immigration of parent species. Since no cool-water stepping stones occur between Hawaii and cool mainland shores of the North Pacific, the divergent cool-water species of Hawaii probably reflect morphological changes occurring after one increment of isolation. Some of these fairly radical changes such as loss of palp articles, coalescence of urosomites, and possibly axial reversal of dominance in gnathopods are seen to be of lower conservative value than heretofore accorded. This upsets classifications in Atylidae, Dexaminidae, Aoridae, and Isaeidae to a significant degree. Official publication date is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year.

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