130 
ler recently has recorded O. profundi from the vicinity of the Phi- 
lippines. If Koehler is right in uniting the Japanese form Ophi- 
actis pteropoma H. L. Clark with O. profundi, — as seems very 
probable — this would indicate that the species is probably distri- 
buted all over the Pacific, and the occurrence of a variety of it 
in New Zealands seas would thus be very well in accordance with 
zoogeographical facts. 
In his paper “ Brittle-Stars, new and old“ (Buil. Mus. C. Zool. 
LXII. 1918. p. 301) H. L. Clark has maintained that the species 
Ophiactis plana Lyman, flexuosa Lyman, perplexa Koehler, profundi 
Ltk. & Mrtsn. and brachygenys H. L. Clark are really all one and 
the same species, which is thus distributed all over the Atlantic 
and Indo-Pacific Oceans and has a bathymetrical range of 26— 
1048 fms. I cannot agree with Clark in this view. It is beyond 
doubt that they are all closely related, as every writer on these 
forms has well recognized. But the unusually great horizontal and 
bathymetrical distribution, which a species comprising all these 
forms would have, must make us look very carefully into the 
matter, before we accept their identity. One of the objections raised 
by Liitken & myself (Op. cit. p. 141) against the identity of O. 
profundi with O. flexuosa, at least, is still as valid as ever, viz. 
that O. flexuosa has only five arms, while O. profundi has constantly 
six arms; “there is no sufficient evidence that in any species the 
young has six arms, the adult only five** — and Clark has given 
no new evidence whatever as to this point. Concerning O. plana 
Lyman, from the Atlantic, the figures given by Clark in his 
“Catalogue of Recent Ophiurans" would seem to show that the 
ventral plates of this species are different in shape from those of 
the New Zealand form; for the rest these figures are not suffic¬ 
iently distinet for allowing a detailed comparison. The faet that this 
species has 6 arms, otherwise, does not, a priori, make it impro- 
bable that it might be identical with O. profundi, but the available 
material does not seem to me to justify declaring them to be 
identical. As for O. brachygenys this form has five arms and is Ihus 
certainly not identical with O. plana or O. profundi, and the same 
holds good with regard to O. perplexa, which is otherwise disting- 
uished by the spines oceurring on the edge of the disk. 
Thus, while agreeing that O. plana and profundi may possibly 
