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POPULAK SCIENCE KEVIETV. 
degree of minuteness lie describes the general features and different 
qualities of tbe reefs, classifying tbem as inner and outer. Next in order 
come coral-islands, in which he speaks of the forms and soundings and 
structure, and then he proceeds to give ample details concerning about 
thirty celebrated formations. Having treated of the islands he then comes 
to the question of the causes of coral-reefs, and here we have a lengthy 
discussion anent barrier, fringing and atoll reefs, the causes modifying their 
forms and mode of growth. This is just the point on which discussion will 
occur among those who have studied the subject: and we cannot help 
thinking that Professor Dana has given his arguments with a considerable 
amount of evidence in their support, and without any of that cavilling 
spirit of which we had to complain so bitterly when, some time since, the 
subject of glacier-motion was under discussion. Then follows a chapter 
on the geographical distribution of corals, and another also on changes ot 
level in the Pacific. Finally comes a discussion on geological conclusions, in 
which the reader is treated to some observations on a host of subjects, of 
which the following are some of the more important: — Formation of lime- 
stones making thick strata of limestone ; deep-sea limestones not of coral 
formation ; absence of fossils from limestone strata; formation of dolo- 
mite and chalk ; limestone caverns ; oceanic temperature ; and lastly, the 
oceanic coral-island subsidence. 
The illustrations are most numerous, and are excessively well executed, 
those which form the frontispiece and are coloured being simply faultlessly 
beautiful. Many of them will be new to all but the special reader. In fine, 
we have to say a word of the author’s style, which assuredly deserves the 
highest commendation. It is surpassed only by that of Mr. Gosse in those 
marvellous word-pictures of the lowly inhabitants of the ocean. But it is 
immensely superior to that of most writers on the subject; and it is so 
fascinating in its nature that it leads you away even over passages in which 
we think the average reader would otherwise fail to have any interest. We 
cannot do better than close this notice with a quotation from the preface to 
this excellent volume: — u Most agreeable are the memories of events, 
scenes, and labours Connected with the cruise ; of companions in travel, 
both naval and scientific ; of the living things of the sea, gathered and 
moving by the ship’s side, and made the study of the day, foul weather or 
fair ; of coral-islands, with their groves, and beautiful life above and within 
the waters ; of exuberant forests on the mountain-islands of the Pacific, 
where the tree-fern expands its cluster of large and graceful fronds in 
rivalry with the palm, and eager vines or creepers intertwine and festoon 
the trees, and weave for them hangings of new foliage and flowers ; of 
lofty precipices richly draped, even the sternest fronts made to smile and 
be glad, as delights the gay tropics, and alive with waterfalls, gliding, 
leaping, or plunging, on their way down from the giddy heights, and as 
they go playing in and out among the foliage, of gorges explored, mountains 
and volcanic cones climbed, and a burning crater penetrated a thousand feet 
down to its boiling depths ; and finally — beyond all these — of man 
emerging from the depths of barbarism, through Christian, self-denying, 
divinely-aided effort, and churches and school-houses standing as central 
objects of interest and influence in a native village.” Thus the author gives 
