56 AUSTRALASIAN ANTARCTIC EXPEDITION. 
Crania, Hemithyris, Terebratulina, Liothyrella, Terebratella and Magellania are still 
widespread in the southern seas in spite of considerable diversities of climate and sea 
temperature. 
There is abundant evidence from the associated molluscan faunas that the 
Patagonian of South America and the Oamaruian of New Zealand enjoyed a much 
warmer climate than the present, and the occurrence of brachiopod species and genera 
in the Oligocene-Miocene of the Antarctic, which are also found in the Patagonian and 
the Oamaruian and the “ Miocene” of Australia, strongly suggests a warmer climate 
for the Antarctic seas of that date also. Tate Regan (1916) supposed from a study of 
the Antarctic fish that that continent was washed by cold seas probably throughout 
the Tertiary period, but the geological evidence all points the other way, and it is probable 
that the fish, like the brachiopods, have accommodated themselves to the increasing 
cold. The suggestion of Willis (1910) that the oceanic deep circulation may have been 
reversed in periods of diastrophic inactivity like the early Tertiary, and that there was 
a creep of warm saline equatorial water along the ocean bottom towards the poles, is 
worthy of serious consideration by zoologists. 
Several genera occurring in the warm Oamaruian seas of New Zealand, and 
probably also of Australia, have apparently been able to survive the late Tertiary 
cooling only in the warmer Australian waters, viz., Aetheia, Murravia, Argyotheca, 
and Magadina. In a similar way Bouchardia, which once extended from Patagonia 
to New Zealand, is now confined to the warm seas of Brazil, while Thecidellina has left 
the southern seas altogether and now occurs only in the tropics (Funafuti, New 
Hebrides,and Jamaica). On the other hand Gyrothyris and Stethothyris persist only 
in the cooler water of Macquarie Island and the Antarctic. 
The larger circum-Pacifie southern districts above discussed all agree in the 
presence of Orania, Liothyrella, and of one or more of the higher genera of the 
Magellanine. The generic dissimilarities now existing between the faunas are of 
three kinds, viz. (1) dissimilarities inherited from the Oligocene-Miocene, such as the 
restriction of Megerlina and Aldingia to Australia, and of Neothyris to New Zealand; 
(2) dissimilarities due to unequal survival of formerly widespread genera as e.g., the 
absence of Hemithyris from Australia, and of Terebratulina from New Zealand, and 
the restriction of Aetheia to Australia, and of Bouchardia to Brazil; (8) dissimilarities 
due to post-Miocene immigrations, such as that of Macandrevia to western South 
America and the Antarctic. 
There are certain generic dissimilarities distinguishing the Recent and Tertiary 
faunas of New Zealand and Australia on the one hand from those of the Antarctic and 
South America on the other that seem to be of great significance. These consist in 
the absence of certain primitive genera of the T'erebratellide from South America and 
the Antarctic, which are present in New Zealand and Australia, viz., Argyrotheca (fossil 
in New Zealand, Recent in Australia), Amphithyris (Recent in New Zealand), Kraussina 
(Recent in Tasmania), and Megerlina (fossil in Tasmania, Recent in Tasmania and 
