'Alert' 1881-2

ECHINODKRMATA. 143
doubt, will be seen, when a large series is to hand, to be nothing
more than varieties of 0. rotata. As none of the arms are complete,
the measurements I could give might only be deceptive ; in them the
upper arm-spines are proportionately lai'ger than in the specimen
already spoken of; the bands separating the plates, the character of
which has given rise to the specific name, may vary -in breadth on one
and the same disk; and the granules may be in narrow or broad bands,
and may be so greatly elongated that they may more correctly be
spoken of as spines ; the marking would by some be spoken of as
exceedingly characteristic, for there extend from the disk on to the
arms two lines of dots of blue ; at every fourth plate, when regular,
the two dots of either side fuse, and the spot enlarges into a blue
patch ; an exactly similar marking is to be seen on the lower sur-
face. In the specimen unhesitatingly placed with 0. rotata there is
not this definite arrangement of the dots.
I have thought it right to direct attention to these peculiarities,
but a full and satisfactory discussion of the subject must be based
on a much larger series of specimens.
These examples were also from Thursday Island.
20. Ophiothrix punctolimbata.
Martens, Arch.f. Nat. 1870, p. 257.
Port Curtis ; Port Molle ; Thursday Island, 3-4 fms. ; Prince of
Wales Channel ; Warrior E-eef.
The specimen from Port Curtis, which is smaller than the others,
has the lateral spines proportionately longer, more echinulated, and
much more glossy.
Lyman, p. 35.
Port Curtis ;
21. Ophiothrix longipeda.
Port Molle.
22. Ophiothrix microplax.
Disk large, covered with short spines, less thick on the radial
shields ; ends of the not-thorny arm-spines faintly clavate. Pro-
portion of arms to disk about 6 to 1.
The disk is rather large (20 millim. in diameter) and is covered
with very short spines, which may almost be described as spinous
granules ; these are not so closely packed on the radial shields or on
the actinal surface as on the rest of the disk. The radial shields
are small, elongated, triangular, the straight base of the one faces
that of the other ; the plates of each pair are separated by several
elongated scales, which carry a few longer spines. There is some
imbrication of the scales on the actinal surface of the disk.