THE Challenger left Portsmouth on December 21, 1872, and on the evening of May 24, 1876, she dropped her anchor at Spithead afcer an eventful voyage, which lasted three and a half years. Shortly after her arrival we gave a sketch of her cruise over the Atlantic and Pacific Oceans. The two volumes just published consist chiefly of an abstract of the less technical portions of the journal kept by Sir Wyville Thomson during the first year of the Challenger's voyage, and duting the early part of the fourth year's voyage, when she was on her way home. During both these periods the Challenger was in the Atlantic, so that we now obtain the record of her survey of this great ocean in a very complete form, and are led to look forward to several additional volumes, in which the account of her cruise in the Pacific Ocean and amongst its fair islands will appear. A great deal of credit must be given to the author of these two splendidly illustrated volumes for his so speedily publishing them. A large portion of one of them was actually passed through the press while the Challenger was at sea, and the preparation of the second volume had to be carried on amid the cares not only of professional duties, but also of getting the immense collections made into order, and of making arrangements for the thorough working out of the scientific results of the voyage. May we express the hope that his energy will enable him speedily to complete the popular narrative of this cruise thus so auspiciously begun. The strictly scientific records of the Challenger voyage cannot be published for some time; the working out cf old forms, the describing and illustrating of new ones, takes time; such work, to be done well, must necessarily be done slowly, and hence we all the more urge on Sir Wyville Thomson to let us have, as soon as can be, the completion of the popular narrative of the general results of his four years' work. This preliminary account is indeed not solely a popular one, for we find in these two volumes a mass of exact scientific details that will make them always works of reference to the scientific student; and while some few of the wondrous new species of animals and plants are but incidentally introduced to us, their descriptions are often so well written, and their forms are so exquisitely portrayed, as to leave us for the time somewhat independent of their more exact scientific diagnosis.