Fauna and Flora of New Zealand. 441 
west; but we may perhaps refer to this period the introduc- 
tion of several of those tropical species, such as Avicennia 
officinalis and Sicyos angularis, which are also found in 
Australia. 
It would thus appear that there have been three migra- 
tions of plants from the north into New Zealand: two of 
very ancient date; the third comparatively recent and com- 
paratively unimportant. ‘The supposition that New Zealand 
was at one time connected with a South-Pacific continent, 
from which plants spread into South America and into New 
Guinea, and that, at a subsequent period, Hastern Australia 
was attached to New Guinea, and received from thence frag- 
ments of this Polynesian flora, together with plants of the 
Indian archipelago, will explain, I think, why some Poly- 
nesian and South-American genera are found in New Zealand 
but not in Australia, and why some occur in Australia but 
not in New Zealand. 
Passing on now to a consideration of our fauna, we find it 
composed of the same elements that we recognized in the 
flora, viz.—(1) Australian, (2) Polynesian, (3) 5. American, 
(4) Antarctic, and (5) North Temperate. The South-Ame- 
rican element seems to be the weakest, but until the distri- 
bution of our insects, land-mollusca, and land-worms is better 
known we cannot speak with any confidence on this point. 
One of our two bats was formerly thought to belong to an 
American family; but this has been shown to be a mistake, 
and it now seems that both are of Old-World extraction. 
This removes a difficulty, for bats are certainly not a more 
ancient group than birds, and it would have been very 
puzzling if their distribution had coincided with that of the 
frogs instead of with that of the birds. 
Our birds show only three elements :—(1) an Antarctic, 
which comprises the penguins, the petrels, three out of five 
gulls, and four out of nine cormorants; (2) a Polynesian, 
consisting of the paroquets, Aplonis, and the long-tailed 
cuckoo; and (3) an Australian, which includes all the rest, 
except a few which are cosmopolitan. Of a South-American 
element we see no trace except it be in Nestor, which may be 
distantly related to the macaws, although still more nearly to 
the brush-tongued parrots of Australia and Polynesia. ‘The 
Merganser of the Auckland Islands may represent the North- 
Temperate element. The affinities of Zurnagra are still 
doubtful. I pointed out in 1872* that our land-birds had 
been derived from the north, and Mr. Wallace has subse- 
* Trans. N. Z. Institute, vel. v. pp. 251, 252. 
Ann. & Mag. N. Hist. Ser. 5. Vol. xiii. 29 
