Fauna and Flora of New Zealand. 433 
from New Guinea and North Australia in an easterly direc- 
tion through the Fiji and Tonga Islands to Samoa, spreading 
south to New Zealand and north to the Ellice, Gilbert, Mar- 
shal, Caroline, and Pelew Islands. This plateau is split into 
two portions by a deep narrow channel, which runs between 
New Zealand and the Kermadec Islands and between New 
Caledonia and the New Hebrides until it almost reaches 
Torres Straits. Another submarine plateau, also never more 
than 2000 fathoms below the sea-level, extends from Chili in 
a north-west direction to the Society Islands and Cook’s 
Islands, including Juan Fernandez, Kaster Island, the Pau- 
motus, and the Marquesas Islands. Between Cook’s Islands 
and the Samoa Islands there is a deep channel, but whether 
this is continued into the deep sea north of Samoa or whether 
the two plateaux are continuous is uncertain. Mr. Wild, of 
the ‘ Challenger’ Expedition, says, ‘ It seems as if an almost 
uninterrupted area of elevation crossed the whole basin of 
the Pacific in a north-westerly direction from Patagonia to 
Japan” *, probably about 1500 fathoms from the surface. 
North of this plateau the ocean averages 3000 fathoms in 
depth. ‘To the south it ranges from 2900 to 2600 fathoms, 
getting gradually shallower towards the south-east. The 
shallowest part of the plateau is the ridge, already mentioned, 
between New Zealand and North Australia, which is nowhere 
more than 1000 fathoms below the surface. 
Here we have probably the remains of an ancient conti- 
nental area, which bridged the South Pacific and allowed the 
passage of frogs, land-shells, insects, and plants between New 
Guinea and South America, but which became submerged 
before the present groups of birds had come into existence. 
The date of this South-Pacific continent must have been 
anterior to the marine Indo-Pacific fauna, because hardly any 
of the fishes, Crustacea, and shells of Polynesia have crossed. 
over to America; and it must have been posterior to the 
appearance of dicotyledonous plants. Now of the genera of 
marine shells characteristic of the Indo-Pacific fauna and not 
found on the American coast, Turbinella, Ricinula, Tridacna, 
and Aspergillum are Miocene; Rimella, Rostellaria, Seraphs, 
Dolium, Ancillaria, Cardilia, Pythina, and Glaucomya are 
Eocene; while Vulsel/a is found in the Upper Cretaceous 
rocks. A few others, such as Nauttlus, Stomatia, and Nerit- 
opsis, are old forms apparently dying out. The genus Mono- 
ceros is also found in the Kocene rocks of Chili, but is not 
known in the Indo-Pacific province. We cannot therefore 
* ‘Thalassa,’ p. 22. 
