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Show 1877.1 CRUSTACEA, CHIEFLY FROM SOUTH AMERICA. 671 Body narrow-oblong, or slightly oblong-oval, with scattered granules, which are disposed in transverse series, only upon the posterior margin of each segment. Head transverse. Eyes large, black, of considerable width, and occupying the whole length of the lateral margin. First three or four segments of the body with the posterior margins straight, the succeeding segments with the posterior margins becoming gradually more concave, and the postero-lateral angles more acute. Segments of the tail with the postero-lateral angles long, narrow, acute, and flexed backwards; terminal segment transverse- oblong, posterior margin tridentate, nearly straight to within a short distance of the postero-lateral angle, then slightly sinuated, postero-lateral angle prominent, triangular, acute. Peduncle of the external antennse with the terminal very little longer than the penultimate joint, flagellum 32-36-jointed. Rami of the uropoda a little unequal, longer than the peduncle, inner with a small slender terminal appendage. Length nearly 1 inch, breadth 5 lines. The specimens in the collection have longer antennse than those described by Milne-Edwards, reaching in one nearly, in another quite, to the extremity of the body. The length of the antennes cannot, however, always be depended upon as a constant specific character; and the number of joints is sometimes variable. The slender styliform appendage to the inner ramus of the uropoda is found in other species of the genus, as, for example, the typical L. aquatica, where it is quite minute. It is absent in many specimens, and is probably very easily disarticulated and lost. This species resembles the Californian L. occidentalis, Dana, U.S. Expl. Exp. xiv. Crust, ii, p. 742, pl. xlix. f. 7 (1853); but the teeth of the terminal segment are more prominent; the antennse are also much longer. The Ligia stimpsoni **, from California, is at once distinguished by its very broad flat body. De Saussure (Mem. Soc. Phys. et Hist. Nat. Geneve, p. 476) found specimens in Cuba which, he says, are not to be distinguished from L. baudiniana; and specimens collected at Rio Janeiro by Dr. Cunningham are referred by Mr. Spence Bate to this species (Ann. & Mag. Nat. Hist. i. p. 443, 446, 1868). Specimens from Rio de Janeiro are also in the British-Museum collection. Family CYMOTHOID^E, CYMOTHOA, Fabricius. CYMOTHOA CESTRUM. ? Oniscus oestrum, Linn. Syst. Nat. ed. xii. p. 1059 (1766); Fab. Syst. Ent. p. 294 (1775). Cymothoa cestrum, Fab. Ent. Syst. ii. p. 505 (1793)?; Leach, Trans. Linn. Soc. xi. p. 372 (1815); Desm. Consid. Crust, p. 307, 1 I propose this name for the Ligia dilatata of Stimpson (Proc. Boston Soc. Nat. Hist. vi. p. 88, 1856-59; and Journ. Boston Soc. Nat. Hist. vi. p. 507, pl xxii. fig. 8, 1857), the name Ligia dilatata having been preoccupied by Brandt for a South-African species of the genus (Bull. Mosc. vi. p. 172, 1833). 44* |