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Show 564 REV. T. R. R. STEBBING ON CRUSTACEANS [May 22, Fam. TRICHONISCIDAE. 1898. Trichoniscidce, Sars, Crustacea of Norway, ii. p. 159. 1900. Trichoniscidce, H. Bichardson, Am.Nat.xxxiv.pp. 302, 306. In separating this family from the Ligiidae, Sars assigns to it the genera Trichoniscus, Trichoniscoides, Haplophthalmus, Scyphacella, and Actoniscus, while leaving to the Ligiidae the genera Ligia, Ligidium, Titanethes, Stgloniscus, and Stgmphalus. In the latter family the first antennae have the third joint minute, the second maxillae have two plumose setae on the inner margin, the maxillipeds have the terminal part distinctly five-jointed, aud the uropods are described as freely projecting behind. In contradistinction to this, in the Trichoniscidae the first antennae have the third joint well developed, the second maxillae are without plumose setae on the inner margin, the maxillipeds have the terminal part generally imperfectly articulated, and the uropods have the peduncle broadly expanded inside and partly covered by the last caudal segment. There are other distinctions drawn by Sars, of more or less importance, to one of which it is specially needful to call attention. In the Ligiidae the second antennae have a " multiarticulate flagellum," whereas in the Trichoniscidae they have a " flagellum composed of only a restricted number of articulations." The restricted number is not specified, but apparently it is not intended to exceed four or five, or seven at most. Now both species included by Dana in his genus Stgloniscus at its institution have the multiarticulate flagellum, which is " seven to ten-jointed " in magellanicus and " about sixteen-jointed " in longistylis. But magellanicus by its maxillipeds and character in general clearly belongs to Trichoniscus. Therefore the distinction between the two families based on the number of joints iu the flagellum of the second antennae is no longer tenable. That Stgloniscus may still belong to the Ligiidae is possible. In the Californian species gracilis, added to the genus by Dana in 1856, the flagellum of the second antennae has about fourteen joints and is nearly as long as the two preceding joints of the peduncle. The peduncle of the uropods is distinguished from that of longistglis by being scarcely twice as long as broad and on the outer side at the middle becoming suddenly narrower. This recalls the corresponding structure in Ligidium hypnorum. Unluckily Dana could not describe the rami because they were mutilated. He does not describe the mouth-organs either in this species or in longistylis, so that the genus remains obscure, coveriug two species which are very doubtfully congeneric. Stgloniscus gracilis is mentioned by Stimpson in 1857, Budde-Lund in 1885, and Miss Harriet Bichardson in 1899 ; but they neither quote nor supplement the meagre description given by Dana in the Pr. Ac. Philad. vol. vii. p. 176. Sars makes the suggestion (Crustacea of Norway, vol. ii. p. 167) . that the genus Scyphacella of S. I. Smith may perhaps turn out to Le identical with Haplophthalmus of Schbb'l. A distinguishing feature of Haplophthalmus is, however, as the name implies, that |