Bathyal and Abyssal Gammaridean Amphipoda of Cedros Trench, Baja California Introduction Collections of l^athyal and abyssal gammaridean Amphipoda M'ere obtained in nine benthic and one epibenthic samples from Cedros Trench, Baja California, by Dr. K. J. Menzies, now of Duke Uni-versity. The benthic samples were collected in 1960-61 with a jSIen-zies trawl from the R/V Velero IV of the Allan Hancock Foundation, University of Southern California. Deep-sea samples collected by Dr. Robert II. Parker, during the "Baja Slope Expedition" of Scripps Institution of Oceanography, from waters to the west of Baja Cali-fornia, 250 miles south of the Cedros Trench, also have been analyzed ; they include some remarkably large species newly recorded from the northeastern Pacific Ocean. A sample of Amphipoda collected in a benthic hagfish trap by Dr. Theodore R. Folsom, off California, to the north of Cedros Trench, is also included because of its singular-ity. Analyses of the Amphipoda are presented herein. Station data and a f amial list are given on pp. 3-5. The name "Cedros," like the Guatemala Trench to the south, is applied to a short portion of the west American trench which borders the continental margin. Cedros Trench lies in the vicinity of Cedros Island, off the middle coast of P>aja California, at approximately 28° N latitude. Few records of bathyal and abyssal Amphipoda from tliis or any portion of the eastern Pacific Ocean have been published. Those works of concern to this area are records of Alhatross material made by Holmes (1008) from middle and southern California, Shoemaker (1925) from the Gulf of California, and J. L. Barnard (1964d) from Alaska to Peru; Galathea collections from Panama by J. L. Barnard (1961) ; Velero IV collections from canyons and basins of California 1