1 877.1 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 pos- 

 terior 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 gradiially 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 trans- 

 verse-oblong, posterior margin tridentate, nearly straight to within a 

 short distance of the postero-lateral angle, then shghtly sinuated, 

 postero-lateral angle prominent, triangular, acute. Peduncle of 

 the external antennae 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 antennae cannot, 

 however, always be depended upon as a constant specific character ; 

 and the number of joints is sometimes variable. The slender styli- 

 form appendage to the inner ramus of the uropoda is found in other 

 species of the genus, as, for example, the typical L. aquafica, 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, pi. xlix. f. 7 (1853); but the 

 teeth of the terminal segment are more prominent ; the antennae 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. haudiniana ; 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^, 



Cymothoa, Fabricius. 



Cymothoa (ESTRUM. 



? Oniscus (Estrum, Linn. Syst. Nat. ed. xii. p. 1059 (1766) ; Fab. 

 Syst. Ent. p. 294 (1775). 



Cymothoa oestrum, Fab. Ent. Syst. ii. p. 505 (1793)?; Leach, 

 Trans. Linn. Soc. xi. p. 372 (1815); Desm. Consid. Crust, p. 307, 



' 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, 

 pi. 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). 



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