64 PRESIDENTS ADDRESS—SECTION C. 
whenever possible, because of my larger acquaintance with their 
several faunas than I have with those of other areas. Taking 
the chief epochs seriatim, I commence with— 
I. Recenr.—The molluscan fauna of the Australian shores con- 
sists of two types as regards geographic origin—(a) That more 
or less intra-tropical, and forms part of the extensive Oriental 
region ; (5) that largely prevailing in the temperate waters, and 
which is endemic as to species, and has many genera peculiar 
or largely Australian in their occurrence. Nevertheless, in the 
typical Australhan fauna there are some species attributable to 
a Palearctic source. They are: Ostrea edulis (O. Angas), 
Laseaa rubra (Poronia australis), Cryptodon flecwuosum, Saat- 
cava artica (S. australis), Lutraria oblonga (L. rhynchaena), 
and Philine aperta (P. Angasi); other alleged identities, as 
among the Polyplacophora, have not been accepted by those best 
competent to decide; nevertheless, antipodean examples of all 
but one of the abovenamed shells have received distinct ve 
names (as given in parentheses), and between these extreme views 
it is difficult to decide what course to follow ; for my part I cannot 
resist the conclusion in respect of Lasea rubra, Cryptodon 
flecuosum, and, perhaps, also, Saxicava arctica, that the species 
are identical in the two widely separated areas. As regards 
Saxicava arctica, we have a remarkable protean shell to deal 
with, and I am in doubt if it be possible to distinguish more 
than one species from Eocene times to the present day in Aus- 
tralia, or even in Europe. | 
In spite of the admission that there are six species of 
mollusca (other than pelagic forms) in common between Western 
Europe and Australia, the proportion is so very insignificant that 
the absolute distinctiveness of the two faunas is incontestable, 
and we may ask ourelves how to account for their presence: in 
Austral Seas? In answer, I suggest as follows:—(a) May we 
not be too rigid in our comparisons between apparently identical 
species, and have restricted our investigations to mere shell-form, 
whilst anatomy may show them to be similitudes; (0) it may 
be that adventitious agencies, operating unrecognised by us, may 
have been concerned in the importation of the European species 
to Australian waters. Dr. Gwyn Jefferies sought to trace Lasewa 
rubra from Western Europe by way of the Arctic Seas to Japan ; 
but there intervenes a geographical hiatus between the last- 
mentioned place to Australia, on the one hand, and to Patagonia 
on the other. Sir James Hector has recorded the appearance of 
a number of marine inhabitants of North Queensland having 
been cast up on the North Coast of New Zealand entangled in a 
mass of drifted seaweed ; whether or not any of these enforced 
migrants have established themselves remains unknown. 
