Professor Agassiz's new book, "A Contribution to American Thalassography," supplies a vacant place in the literature of oceanic basins. The book is the result of several cruises on board the steamer "Blake" of the U. S. Coast Survey. The materials collected furnish valuable information for the study of animal life in deep water, and the conclusions arrived at cause new views to be taken of the former positions of the continents and of the history of submarine deposits. Considerable space is devoted to the discussion of the geological history of Florida. Louis Agassiz asserted that the formations of Florida could not be explained by the "subsidence theory" of Darwin, but no other explanation could be given at that time. Professor Agassiz has arrived at a rational and satisfactory explanation of its distinctive peculiarities. Great stress is laid upon the various changes of the ocean currents, and on the importance of the transportion of pelagic food by currents in controlling the growth and distribution of corals. There is also a careful discussion of the characteristic deep-sea animals-fishes, jelly-fish, corals, etc. A complete account is given of the development of the apparatus and of the methods employed in dredging. Several improvements were invented by Prof. Agassiz. The results of his study show that the changes of elevation have been very slow and slight, with very little disturbance of the strata, and that the eras of depositions, from the Eocene to the present time, have been marked by the same processes which, even now. may be observed in action.