The finality of this work is to register the occurrence of a Crustacean denominated "Lagostim" - Nephrops rubellus MOREIRA - found in waters of the neighbourhood of Xavier Island, off the coast of the State of Santa Catarina (Brazil). This specimen was captured in a "trawl" net by the fishing boat "Libertador" in depth of 30 to 60 fathoms (66-132 m), in the middle of June 1950. The species which was described in 1903 by CARLOS MOREIRA, does not seem to be of a very common one at the Braz lian coast, its cxistance having been, however, recorded from the Argentine coast, by DOELLO JURADO, in 1938. The present v/ork seems te be justified since it deals with a Crustacean never mentioned, in our specialised literature since its description half a century ago and also by being the characters of this specimen not exactly the same as the previously deseribed. A key has been worked out for the genus Nephrops, for the determination of the Atlantic and Indo-Pacifc species, the key organized by DE MAN was adopted as a starting-point.