DESCRTPTTONS OF NEW DECAPOD CRUSTACEANS FROM THE WEST COAST OF NORTH AMERICA. By Mary J. Ratiibun, Second Assistant Curator, /)/vv>/o« of Marine Invertebrates. The species and subspecies here described are the result chietiy of a study of the vast collection of shrimps from the coast of Alaska south-^vard to San Dieo-o, CalifoT'nia, which have been accumulatin<>' for many years iti the ITnited Statt^s National Museum, and have been obtained laroely In" the I'nited States Fish Conunission steamer A/hfffross. Resides the siu-imps, one new crab, an Oregonia^ was dredo-ed bv the AJhutros.s (\\\y\\\^ her cruise in Bcrinof Sea in 1900. In comiection with the ])ublication of the Decapod Crustacea of the Hai'riman Expedition, it is proposed to give a list of the foi"ms known to inhabit i\\v coast of western America (north of Mexico) and to nioit' fully desci'il»(' and figure the new and little-known species. Family MAHDiE. OREGONIA BIFURCA. Surface tuberculate and hairy. Postorbital width two-thirds of branchial width. Rostral horns diverj»-ent from their base. Basal joint of antenna armed on its outer edoe with a stout l)lunt subter-iniiial spine and three small spines, one of which is at the anterior anulc. Inner surface of merus of chelipeds bordered by short blunt spines; propodus sli«jhtly lonyer than merus, tinj^crs and palm sub-ecpial. marnins of palm sul)parallel. Dactyli of ambulatory ley's con-tained al)out one and a third tinu^s in their propodi. Pliinn.'-tionx. — Lenijth of carapace" and rostrum 20.5 mm., width of carapace \\)A\ nun., width between tips of postorbital spines 13 mm., leneth of hoin measured alon^r the inner edge 8.1 nun., distance between tips of horns I'..;") mm. Type locallti/. — One specimen only, a female, was taken b}' the U. S. Fish (^onunission steamiM-Alhaiross at station 8785, north of Rat Islands, Aleutians. i'7(» fathoms (Cat. No. 25287). Proceedings U. S. National Museum. Vol. XXIV— No. 1272. 885
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