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

ECHINODEBMATA. 145by the fact that two successive plates are so marked, and that thenthere is an interval of two or more not so distinguished. Three orfour blackish dots are to be found on the radial shields, along theline of the vertical side ; by pairs or threes the upper arm-plates arefaint pink or light green, and the pink ones are distinguished byeach having a black dot.I have taken advantage of the locplity of this Avell-marked andreally beautiful species to associate with it a name honoured byus all.Port Darwin, 7-12 fms., mud and sand.24. Ophiothrix melanogramma.Disk pentagonal in appearance, completely covered with finespinules, which are a good deal longer and rarer on the actinal surface.Arms 4-5 times the diameter of the disk, tapering very delicately; the upper surface marked by a black line, which extends agood way on to, but does not reach, the centre of the disk.The radial shields are almost completely obscured by the spinulation,which is very delicate ; mouth-shields broader than long, theinner sides meeting at an acute angle, the outer edge rather evenlyrounded, the l^ridge between the genital slits very narrow ; seven oreight arm-spines, the two lowest very small, the upper one as longas five or six upper arm-plates, but the uppermost of all is not thelongest ; the upper spines are richly and delicately echinulated, and,owing to the great encroachment of the side arm-plates on the uppersurface of the arm, the spines of either side come to lie very close toone another, and soon obscure the arm itself. One small tentaclescale.The lower arm-plates have a concave notch on their adoraledge, have a short side passing into the short lateral edge, and arethree-sided on their aboral face, so that they form an irregularhexagon which is broader than long. Owing to the size of the sidearm-plates, the upper arm-plates are lozenge-shaped.This species has a most elegant appearance, the black band alreadyspoken of relieving the whiteness of all the other parts, while a kindof feathery appearance is given to the arms by the delicate platesand long glassy spines.Prince of AVales Channel.Li/man, p. 37.25. Ophiomaza cacaotica.The coloration of these specimens is very far from the chocolateof Mr. Lyman's type ; but three specimens collected in one locality(Gulf of Suez) are—one chocolate-coloured, one quite light, and oneintermediate. A discussion, however, of the characters of thevariations of this species will be more profitable when our series islarger.Port Mollc ;Prince of Wales Channel.I.