'Alert' 1881-2

ECHINODEBMATA. 145
by the fact that two successive plates are so marked, and that then
there is an interval of two or more not so distinguished. Three or
four blackish dots are to be found on the radial shields, along the
line of the vertical side ; by pairs or threes the upper arm-plates are
faint pink or light green, and the pink ones are distinguished by
each having a black dot.
I have taken advantage of the locplity of this Avell-marked and
really beautiful species to associate with it a name honoured by
us all.
Port Darwin, 7-12 fms., mud and sand.
24. Ophiothrix melanogramma.
Disk pentagonal in appearance, completely covered with fine
spinules, which are a good deal longer and rarer on the actinal sur-
face. Arms 4-5 times the diameter of the disk, tapering very deli-
cately ; the upper surface marked by a black line, which extends a
good 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, the
inner sides meeting at an acute angle, the outer edge rather evenly
rounded, the l^ridge between the genital slits very narrow ;
seven or
eight arm-spines, the two lowest very small, the upper one as long
as five or six upper arm-plates, but the uppermost of all is not the
longest ; the upper spines are richly and delicately echinulated, and,
owing to the great encroachment of the side arm-plates on the upper
surface of the arm, the spines of either side come to lie very close to
one another, and soon obscure the arm itself. One small tentacle-
scale. The lower arm-plates have a concave notch on their adoral
edge, have a short side passing into the short lateral edge, and are
three-sided on their aboral face, so that they form an irregular
hexagon which is broader than long. Owing to the size of the side
arm-plates, the upper arm-plates are lozenge-shaped.
This species has a most elegant appearance, the black band already
spoken of relieving the whiteness of all the other parts, while a kind
of feathery appearance is given to the arms by the delicate plates
and long glassy spines.
Prince of AVales Channel.
Li/man, p. 37.
25. Ophiomaza cacaotica.
The coloration of these specimens is very far from the chocolate
of Mr. Lyman's type ; but three specimens collected in one locality
(Gulf of Suez) are—one chocolate-coloured, one quite light, and one
intermediate. A discussion, however, of the characters of the
variations of this species will be more profitable when our series is
larger.
Port Mollc ; Prince of Wales Channel.
I.