Report on the zoological collections made in the Indo-Pacific Ocean ...

CRTTSTACEA. 20533. Euxanthus tuberculosus. (Plate XIX. fig. A.)Carapace transverse, moderately convex, everywhere covered withnumerous closely- set rounded tubercles, which in the adult arethemselves distinctly puuctulated ; similar tubercles cover the outersurface of the wrist and palm of the chelipedes and the posteriorsurface of the ambulatory legs ; the cervical suture and the suturedefining the anterior part of the mesogastric lobe are deep and welldefined ; the tubercles are smallest, but yet distinct, on the cardiacand intestinal regions and posterior and postero-lateral margins ; thefrontal margin is divided by a rather deep median notch ; the anterolateralmargins are divided into four rounded tuberculated lobes,the first of which is often scarcely distinguishable. The parts of thebody immediately below the antero-lateral margins are granulated,but the rest of the inferior surface is nearly smooth, the sternumand postabdomen rather coarsely puuctulated ; the basal antennaljoint enters (in the adult) well within the inner orbital hiatus ; themerus-joiut of the outer maxillipedes is transverse and much shorterthan the preceding joint. The chelipedes are robust ; the merus orarm short, and tuberculated at its upper and distal extremity ; wristand palm (as stated above) closely tuberculated on their upper andouter surfaces, the tubercles, even in the adult, somewhat conicaland acute ; inner margin of the. palm having some small granules;fingers shorter than the palm, denticulated on their inner margins,and having between them when closed scarcely any hiatus ; mobilefinger granulated above at base ; both fingers obtuse and rounded atapex, or (in the smaller examples especially) even somewhat excavated.The fourth to sixth joints of the ambulatory legs are compressed,tuberculated ; the tubercles (of the superior marginespecially) high, conical, and acute ; the dactyli are small, slender,armed with small subspiniform granules, and pubescent distally, witha small naked terminal claw. Length of the largest adult example(from which the description is taken) 11 lines (23 millim,), greatestwidth nearly 1 inch 4 lines (33 millim.).Of this species, an apparently adult but not full-sized maleand female are in the second collection from Thursday Island(No. 167), obtained on the beach; a young male from the samelocality (No. 177), and another young example from WarriorReef, Torres Straits, 10 fms. (no. 137). There are in the British-Museum collection a male from N. Australia {Dr. J. R. Elsey),and an adult male from the Australian seas without definite locality,from which the description and figure are taken {Dr. J. S.Bowerhank). The coloration varies in the different examples, aUof which are preserved in spirit : the two specimens which havebeen longest in the collection are a chocolate- brown ; the two largestspecimens in the Alert ' ' collection (No. 107) are of a deep purplishred, and the two smallest of a bright orange hue.As the basal antennal joint enters well within the inner orbitalhiatus (see fig. a), this species must, I think, be referred to thegenus Euxanthus, from all the species of which genus known to me