8 JOURNAL OF SCIENCE 
plateau is the ridge, already mentioned, between New Zealand 
and North Austratia, which is nowhere more than 1000 fathoms 
below the surface. 7 
Here we have probably the remains of an ancient continen- 
tal area, which bridged the South Pacific, and allowed the pas- 
sage 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 dicotyle- 
donous plants. Now of the genera of marine shells character- 
istic of the Indo-Pacific fauna and not found on the American 
coast, TZurbinella, Ricinula, Iridacna, and Aspergillum. are 
miocene; zmella, Rostellaria, Seraphs, Dolium, Ancillaria, 
Cardilia, Pythina. and Glaucomya are eocene ; while Vzlsella is 
found in the upper cretaceous rocks. A few others, such as 
Nautilus, Stomatia, and WNeritopsis are old forms apparently 
dying out. The genus Monoceros is also found in the eocene 
rocks of Chili, but is not known in the Indo-Pacific province. 
We cannot therefore put the South Pacific continent later than 
the cretaceous period. On the other hand, though fossil plants be- 
longing to the jurassic period are known from many parts of the 
world, not a single dicotyledon has as yet been found among 
them, the oldest known form being a Poplar from the lower cre- 
taceous beds of Greenland. In the upper cretaceous epoch dico- 
tyledonous plants were abundant in Europe, North America, 
and in tropical Africa, and each of the three classes, J/onoch- 
lamydee, Polypetale, and Gamopetale were represented. The 
South Pacific continent must therefore have existed after the 
jurassic, and must have been submerged before the eocene 
period. 
Let us now see what light the geology of the surrounding 
countries throws on the subject. To commence with Chili. 
From Mr. Darwin’s “Observations on the Geology of South 
America” we learn that the fundamental rock system of Chili 
and Western Tierra del Fuego consists of an irregular plateau 
of mica-schist and gneiss. On this floor immense masses of: 
volcanic rocks, chiefly andesites and diorites, have been poured 
out from submarine volcanoes, forming the ranges of mountains 
called the Andes. These mountains are highest in the north, 
and get lower and lower southwards, but portions of volcanic 
rocks are found all through to Tierra del Fuego. High up 
among the volcanic rocks of the Andes in Chili a sedimentary 
gypseous system occurs, containing fossils of the lower cretaceous 
or perhaps upper jurassic period. Fossils of the same age are 
also found in a clay-slate system forming the eastern side of 
Tierra del Fuego, and stretching far up the eastern flanks of the 
Andes. These lower cretaceous rocks go to a length of 14,0o00ft. 
or 15,000ft. above the sea. On the Atlantic side, enormous 
