'Alert' 1881-2

142 COLLECTIONS FROM MELANESIA.
become less conspicuous and much reduced ; the white lines along
the arm are broken into by blue patches, much less extensively developed
than in the dark form ; on the lower surface of the arm
the blue lines may be present as continuous" tracts, or they may here
and there be interrupted by white.
Port Curtis ; Thursday Island ; Port Darwin.
Lyman, p. 36.
Thursday Island.
Lyman, p. 36.
Port Darwin.
Lyman, p. 85.
Port Jackson, 0-5 fms. ;
16. Ophiothrix striolata.
17. Ophiothrix galatesB.
18. Ophiothrix ciliaris.
Port MoUe.
„ 19. Ophiothrix rotata.
Martens, Arch.f. Nat. 1870, p. 258.
A single specimen, without doubt referred to this species, differs
in one or two points from tbat described by Dr. von Martens. In
the Berlin-Museum specimen the diameter of the disk is 7 millim.,
and the length of the arras 35 millim. In our specimen the arms
must have been nearly 150 millim. long, while the diameter of the
disk is 12 millim. The upper spines are not more than twice the
width of the arm, instead of four times. The original describer
makes two statements with regard to the colour of the oral shields :
—" Unterseite der Bcheibe mit den Muudschildern und die Arm-
stacheln blass " ;
and " Das der Madreporenplatte zi;gehorige Mund-
schild ist merklich grosser, an den Heiten nicht eingebuchtet und
weiss, nicht wie die andern violett." In the specimen now under
examination there is some violet marking on each one of the mouth-
shields.
Thursday Island, 3-4 fms.
So far as the present collection allows me to form any ideas with
regard to the range of variation within the limits of a " species," and
the value of the colour-markings on which previous investigators have
laid, and, as it seemed, justifiably, very considerable stress, I am inclined
to the view that the variation is very much greater than was
supposed, and that, after all, colour-marking, though an important
aid in the discrimination of the species, can hardly be said to have
the value which has been attached to it. The doubts first raised
by a study of 0. martensi (vide supra) are not a little strengthened
by the three specimens now lying before me, which, I have little