406 
which was, moreover, very considerably smaller during the time 
before the great subsidence of the New Zealand Plateau. This will 
easily account for the occurrence at New Zealand of such species as 
Heliocidaris tuberculata. Echinocardium australe, Ophiactis resiliens 
and Stichopus mollis, probably also Chiridota gigas. On the other 
hånd, Holopneustes inflatus has certainly not pelagic larvæ; even 
if it can be maintained as separate from H. purpurascens, it is sure 
to have a shortened development like the latter.^) The relatively 
large eggs of Åmphiocnida pilosa indicate that this species has not 
pelagic larvæ either, and the same probably holds good for Allo- 
stichaster polyplax and Phyllophorus dearmatus. A passage of these 
forms across the deep-sea that now separates the two regions is 
hardly imaginable either in a pelagic stage or by means of trans¬ 
port on floating algæ, and even the raising of the northern exten- 
sion of the great New Zealand Plateau would not make the direct 
transport across the separating sea very probable. 
Holopneustes undoubtedly has its original home in Australia, but 
has extended its range to New Zealand; it forms an interesting 
parallel to Pseudechinus, which has, evidently, its home in the New 
Zealand region but has apparently extended its range to Australia, 
where it would appear to be represented by one species (cf. p. 399).-) 
Heliocidaris tuberculata is doubtless also of Australian origin. As 
regards the other littoral-sublittoral species common to both regions 
it is, for the present, at least, hardly possible to form a definite 
opinion, whether they belong originally to the Australian or the 
New Zealand region. 
It is worth emphasizing that two species which were hitherto 
regarded as com.mon to Australia and New Zealand, viz. Ophionereis 
Schayeri and Ophiomyxa australis, are not really so, the New Zea¬ 
land forms representing two well defined species, Ophionereis fasciata 
1) T h. M o r t e n s e n. Preliminary note on the remarkable shortened devel¬ 
opment of an Australian sea-urchin, Toxocidaris erythrogrammus. Proc. 
Linn. Soc. N. S. Wales. XL. 1915. p. 206. 
“) It is worth recalling in this connection that the species Amblypneustes 
pachistus H. L. Clark (Hawaiian a. o. Pacific Echini. The Pedinidæ etc. 
Mern. Mus. C. Z. XXXIV. 1912, p. 327) was founded partly on specimens 
labelled New Zealand. Clark himself regards this as incorrect labelling, 
the species being known with certainty only from Westernport, Australia. 
