16 JOURNAL OF SCIENCE. 
The marine mollusca are, like the marine fishes, a southward 
extension of the Indo-Pacific fauna with a well-marked Antarctic | 
element; the South American element being but slightly de- 
veloped. The main point of interest is the difference exhibite d 
between them and the marine mollusca of temperate Australia 
and Tasmania, shewn chiefly in the absence from our seas of 
many common sub-tropical forms. Tasmania, for example, pos- 
sesses several species ot Conus, Cyproa, Fasciolaria, and Oliva, 
of which we have no representatives. We have but one species 
each of the genera Mitra, Columbella, and Nassa ; while Tas- 
mania has respectively fourteen, ten and five species. We have 
only three species of Voluta and two of MWarginella, while Tas- 
mania has seven of the former and eight of the latter. This 
great difference is probably accounted for by the warm north- 
east current that flows down the coast of Australia, and the cold 
south-west current that sweeps the shores of New Zealand. If, 
however, New Zealand was joined to Northern Australia or New 
Guinea all this would be changed, the warm current would pass 
down its east coast, while the cold current would be deflected 
from the west coast of New Zealand to, the east coast coast of 
Australia. But the difference in the shells was as well marked 
in tertiary times as now; consequently we must suppose that 
New Zealand has been isolated, and that the warm current has 
passed down the east coast of Australia ever since these genera 
inhabited the districts. Now Voluta, Mitra, Conus, Fasciolaria, 
and Cyprea date from the upper cretaceous, the others from the 
eocene, and the conclusion seems plain that New Zealand has 
not been connected with Australia since the cretaceous period, 
which agrees well with the inference derived from the fragmentary 
nature of our avifauna, 
The geographical relations of our insects and spiders are not 
yet known, but as the families of insects in many cases date 
back to the jurassic, and several genera to the cretaceous period, 
we may expect to find a marked South American element 
among them; indeed Mr. Meyrick has, in papers read to our 
society, already pointed out that in the Crambide the New Zea- 
land species of Diptychophora are more closely related to South 
American than to the single Australian species ; and that among 
the Geometrina, the genera Azelina, Drepanodes and Siculoides 
are South American, while Za¢osoma is found in Europe, Ceylon, 
Borneo, Australia and South America; the New Zealand species 
being nearest to those of South America. Perzpatus is no doubt 
avery old form. It is found in S. Africa, Chili, Central America 
and the W. Indies, and consequently cannot be considered as 
representing an Antarctic element, but must be referred to the 
South American migration. 
It is very remarkable that our crayfishes should belong to the 
same genus as the species found in Fiji, while those of Austra- 
lia and South America are generically distinct, although all be- 
long to the same sub-family. This, I think, proves incontest- 
ably that Fiji and New Zealand have had direct land communi- 
