: 
REVIEWS AND BOOK NOTICES. 675 
The chapters treat of ‘‘ Corals and Coral Makers ;” the “ Struc- 
ture of Coral Reefs and Islands ;” the ‘‘ Formation of Coral Reefs 
and Islands, and Causes of their Features ;” the ‘* Geographical 
Distribution of Coral Reefs and Islands ;” the “Changes of Level 
in the Pacific Ocean ;” and ‘Geological Conclusions ;” with an 
Appendix, giving explanatory remarks on geological time, radi- 
ates, protozoans and a list of the names of species in the author’s 
report on zoophytes, the latter prepared by Professor Verrill. 
While the first chapter gives an exhaustive and richly illus- 
_ trated account of corals and coral polyps, we pass to some of the 
more general results of the author’s studies. In speaking “a 
good word for coral reefs,” the dread of navigators, he remarks 
that besides affording fishing grounds and harbors, “the wide 
coral banks and the enclosed channels greatly enlarge the limits 
tributary to the lands they encircle. Besides being barriers 
against the ocean, they are dikes to detain the detritus of the 
hills. They stop the water of the streams and cause it to drop 
the silt they were bearing off, and thus secure an addition to the 
They prevent, therefore, the waste which is. constantly 
going on about islands without such barriers; for the ocean not 
only encroaches upon the unprotected shores of small islands, but 
carries off much of whatever the streams empty into it. The 
delta of Rewa on Viti Levu, resulting from the detritus accumu- 
lations of a large river, covers nearly sixty square miles. This is 
an extreme case in the Pacific, as few islands are so large and 
Consequently rivers of such magnitude are not common. But 
there is rarely a coral-girt island which has not at least some 
= “arrow plains from this source; and upon them the villages of 
_ the natives are usually situated. Around Tahiti these plains are 
: “om half a mile to two or three miles in width and the cocoa-nut 
‘ and bread fruit groves are mostly confined to them.” - 
7 After having shown that atolls, and to a large extent other coral 
_ Teefs, are registers of change of level, he shows that a large part 
f the Pacific Ocean must have undergone great oscillations in 
a recent geological time. As proofs of elevation, he cites (1) “the 
existence on coral or other islands of patches of coral reef and 
; deposits of shells and sand from the reefs, above the level where 
Y are at present forming.” (2) On islands not coral, the exis- 
ex >of sedimentary deposits, or layers of rolled stone, inter- 
stratified among the layers of igneous or other rocks constituting 
