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

—;282 COLLECTIONS PKOM MELANESIA.Seven specimens were collected at Port Darwin at 12 fms (includingboth sexes) ; two or three are females with ova. In thelast collection from H.M.S. ' Alert ' specimens from Singaporeare apparently not specifically distinguishable, although presentingsome slight distinctions.From Oebiopsis nitidus, A. M.-Edwards *, from the Cape Verds(the type of the genus), this species is distinguished by the somewhatdifferent form of the rostrum, the existence of a spine on thecarpus of the chclipedes, the much shorter antennulary and antennalpeduncles, &g.A male from Freraantle, S.W. Australia {Dr. J. S. Bowerhanlc),differs in the form of the rostrum, which is anteriorly deflexed ; itsmargins armed with ten spines in front of the first of the denticulesof the sides of the head ; of these, four (of which two are longer) arearranged in a semicircle in front, and three, posterior to them, oneach side. I would propose to designate this, if specifically distinct,G. bowerbanJcii.The genus Gehiopsis scarcely differs from. Gebia, except in thegreater development of the lower finger of the chclipedes (whichthus are perfectly chelate), and is probably to be regarded as a sub-3. Axius plectrorhynclius, StraJd.I am somewhat uncertain of the identity of the specimen in the' Alert ' collection with Strahl's type from Luzon, and thereforesubjoin the following description :The carapace and postabdomen are somewhat membranaceous intexture, as in most species of the genus. The cephalothorax is verticallydeep and laterally compressed ; the carapace is smooth,without spines, and has the cervical suture distinctly marked. Therostrum is prominent and narrow, concave above between the eyesit is produced somewhat behind them, and is armed on the lateralmargins with five or six teeth ; at the base of the rostrum, in themedian dorsal line, the carapace rises into an abrupt prominenceboth the gastric and cardiac regions are distinctly defined. Thepostabdominal segments are smooth, the first very small, the restnearly of equal length ; the lateral margins of the second to sixthsegments are nearly straight, entire, and are not produced into spinesat either the antero-lateral or poster o -lateral angles ; the terminalsegment is quadrate, very little broader than long, a little broaderin its proximal than in its distal half, and has its posterior marginstraight. The eyes are of moderate length and thickness, and havedistinct black corneas ; the antennules are of moderate length, theirantepenultimate joints longer than the two following, which aresubequal ; the two flagella are of equal thickness, with naked joints.The antennae are shorter than the animal, the antepenultimate jointof the peduncle shorter than the following, and armed beneath witha small spinule ; the penultimate joint longer than the last joint ; the* NouT. Archiv. Mus. Hist. Nat. iv. p. fi3, pi. xviii. figs. 4-7 (1868).