AND CORAL ISLANDS. BY JAMES D. DANA, LL.D., PROFESSOR OF GEOLOGY AND MINERALOGY IN YALE COLLEGE; AUTHOR OF REPORTS, IN "We wandered where the dreamy palm And through the waters clear and calm, J. C. P., U. S. N. Expl. Expd. NEW YORK: DODD & MEAD, PUBLISHERS. No. 762 BROADWAY. 1872. PREFACE. THE object in view in the preparation of this work has been to present a popular account of "Corals and Coral Islands," without a sacrifice of scientific precision, or, on the main topic, of fulness. Dry details and technicalities have been avoided as far as was compatible with this restriction, explanations in simple form have been freely added, and numerous illustrations introduced, in order that the subject may have its natural attractiveness to both classes of readers. I have opened the volume with a chapter on "Corals and Coral makers," describing, under it, the forms and structure of polyps; how they live and grow and hold their own in a world of enemies; how coral-making species secrete their coral; how they multiply, and develop their large clusters, spreading leaves and branching forms, so much like those among plants; and in what seas they thrive, and under what conditions produce the coral plantations. All this is prefatory to the following part of the volume on Coral Reefs and Islands, which comprises a description of the features and structure of these reef-formations, an account of their mode of accumulation and increase, and a discussion of |