lbergia, Eucalyptus, Diospyros, Dryandra, Casuarina, and Ficus;
and also such northern genera as Acer, Planera, Ulmus, Quercus, Alnus,
Myrica, and Sequoia. All these latter, except Ulmus and Planera, have been
found also in the Eastern-Australian Tertiaries, and we may therefore
consider that at this period the northern temperate element in both floras
was identical. If this flora entered both countries from the south, and was
really Antarctic, its extinction in New Zealand may have been due to the
submergence of the country to the south, and its elevation and extension
towards the tropics, admitting of the incursion of the large number of
Polynesian and tropical Australian types now found there; while the
Australian portion of the same flora may have succumbed at a somewhat later
period, when the elevation of the Cretaceous and Tertiary sea united it
with Western Australia, and allowed the rich typical Australian flora to
overrun the country. Of course we are assuming that the identification of
these genera is for the most part correct, though almost entirely founded
on leaves only. Fuller knowledge, both of the extinct flora itself and of
the geological age of the several deposits, is requisite before any
trustworthy explanation of the phenomena can be arrived at.

[187] The following are the tropical genera common to New Zealand and
Australia:--

1. _Melicope._ Queensland, Pacific Islands.
2. _Eugenia._ Eastern and Tropical Australia, Asia, and America.
3. _Passiflora._ N.S.W. and Queensland, Tropics of Old World and America.
4. _Myrsine._ Tropical and Temperate Australia, Tropical and Sub-tropical
regions.
5. _Sapota._ Australia, Norfolk Islands, Tropics.
6. _Cyathodes._ Australia and Pacific Islands.
7. _Parsonsia._ Tropical Australia and Asia.
8. _Geniostoma._ Queensland, Polynesia, Asia.
9. _Mitrasacme._ Tropical and Temperate Australia, India.
10. _Ipomoea._ Tropical Australia, Tropics.
11. _Mazus._ Temperate Australia, India, China.
12. _Vitex._ Tropical Australia, Tropical and Sub-tropical.
13. _Pisonia._ Tropical Australia, Tropical and Sub-tropical.
14. _Alternanthera._ Tropical Australia, India, and S. America.
15. _Tetranthera._ Tropical Australia, Tropics.
16. _Santalum._ Tropical and Sub-tropical Australia, Pacific, Malay
Islands.
17. _Carumbium._ Tropical and Sub-tropical Australia, Pacific Islands.
18. _Elatostemma._ Sub-tropical Australia, Asia, Paci