340 On Coral Reefs and Islands. 
the westernmost islands, which have been longest free from such 
action, have reefs of considerable extent. The island of Maui 
exemplifies well the general fact. The island consists of two 
~ nsulas: one, the eastern, recent voleanic, with a large crater 
summit, and the other, the western, presenting every evidence 
re its gorges and peaks andabsence of volcanic cones, a saa 
become extinct ages since. In conformity with the view ex- 
pressed, the coral reefs are confined almost eheeteeghpa to the 
latter peninsula. Other examples are afforded by the Samoan 
Islands. Savaii abounds in extinct craters and lava streams, and 
much resembles Hawaii in character: it bears proof in every part 
of being the last seat of the volcanic fires of Samoa. Its reefs 
are consequently few and small: there. is but a narrow line on 
part of the northern shores, although on the other islands they 
canic action. Submarine eruptions, which are frequent as long 
voleano near the sea is in action, heat the waters, and de- 
stroy whatever of life they may contain: after the eruption of 
Kilauea, in 1840, there. were numerous dead fish thrown on the 
beach ; and many such instances in different regions are on 
record. Other facts, illustrating the effects of volcanic heat in 
preventing the growth of reefs, will be brought forward’ in the 
following pages. 
The agencies affecting the growth of coral reefs being before 
the mind, we may proceed to notice the actual distribution of 
reefs. through the coral seas. The review given is a rapid one, 
as our present object is simply to explain the absence or ‘presence 
Bay. reefs within the coral reef limits, by reference to the above 
cis.* 
Pacific Ocean.—The west coast bf South wihotidh is known 
to be without coral reefs even immediately beneath the equator ; 
and the seas of the Galapagos also grow no il The north- 
ward deflection of the coral boundary line, as shown, accounts 
for their absence. In =o harbor of Callao (the seaport of Lima), 
the temperature is sometimes down to 59° or 602 F., and at the 
Galapagos, Captain Fitzroy found the waters in September to fall 
often to 62° F., and once to 58} F. This month, it should be 
observed, cannot be the coldest of the year. In the bay of Pan- 
ama, ‘coral is reported to occur, but there are no reefs.t 
_ * In the valuable work by Mr. Darw eographical distribution of reefs is 
ee of at oe in the a pp- % in sat 7 i facts reat detailed have 
independent sources, except where otherwise acknowl In 
acoouaaiine ter a distribution of ree fs, Mr. Darwin has. erred in at- 
tributing too fiiuch weight to a supposed differ ae Me the amount of subsidence 12 
different regions, negle ing to allow the requi te limiting influence to volcanic 
agency, and to ioned. 
our. Roy. Geog. Soc., i, 69, on the Isthmus of Panama, by J. A. Lloyd, © 
