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THE VOYAGE OF H.M.S. CHALLENGER. 
Leucosia, F abricius. 
Leucosia, Fabricius, Entom. Syst. Suppl., p. 349, 1798. 
„ Milne Edwards, Hist. Nat. Crust., vol. ii. p. 121, 1837. 
„ Bell, Trans. Linn. Soc. Lond., vol. xxi. p. 281, 1855. 
. Carapace convex, semiglobose, smooth and usually polished, without tubercles or 
indications of the regions of the dorsal surface, the anterior part of the cervical region 
usually prominent, the front either triangulate, truncated, or with a median cusp. The 
antero-lateral margins defined by a granulated line, which may extend for a short distance 
along the postero-lateral margins ; beneath the lateral margins is an excavated pit, 
defined in front of the bases of the chelipedes by a series of granules, and continued as a 
shallow excavation beneath the postero-lateral margins ( sinus thoracicus, Bell). The 
post-abdomen in the male is large and covers the sternum at the base between the fifth 
ambulatory legs ; the first and last segments are usually distinct, the remainder either con- 
solidated or divided by a median suture. The eyes and orbits are extremely small ; the 
orbits circular ; the antennules are somewhat obliquely plicated ; the minute antennae are 
placed beneath the antennules ; their basal joint does not attain the frontal margin and 
the small flagellum enters the interior hiatus of the orbit. The exterior maxillipedes 
completely cover the buccal cavity, the triangulate acute merus of the endognath covers 
the following joints ; the exognath is distally obtuse and its exterior margin is straight or 
nearly so. Chelipedes in the adult male subequal, with the merus strongly granulated at 
its base and usually along the margins ; carpus and palm usually granulated on the interior 
margins, palm compressed, fingers distally acute. Ambulatory legs rather small, with 
the joints unarmed, dactyli styliform and compressed. 
The species of this well-known genus are numerous and are often remarkable for the 
beauty of their coloration ; they occur commonly in the littoral and shallower waters of 
the Indo-Pacific region. 
Besides the species described or adverted to by myself in the memoir above alluded 
to, the following have been described since the publication of Mr. Bell’s monograph : — 
Leucosia splendida, Haswell. Port Jackson. 
Leucosia leslii, Haswell. Torres Strait (Darnley Island) ; 
and two new species, Leucosia australiensis and Leucosia haswelli, are described below. 1 
Leucosia australiensis , n. sp. (PI. XXVII. fig. 1). 
The carapace is convex, smooth, and has a few scattered punctulations, which are 
absent from the parts near to the posterior and postero-lateral margins. The antero- 
1 The species described, by Haswell as Leucosia cheverti is probably, as I have shown, identical with Leucosia whitei, 
Bell. I have also described a new variety of the common Leucosia craniolaris, leevimana (Crust, in Rep. Zool. Coll. 
H.M.S. “ Alert,” p. 250, pi. xxvi. fig. A) from the Torres Strait. The variety viridimaculata, Haswell, of Leucosia 
reticulata, Miers, is not sustained by Mr. Haswell in bis Catalogue of the Australian Crustacea, 1882. 
