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2. A Monograph of the Cirripedia with figures of all the species: the Balanidæ or sessile Cirripedes, the Verrucidæ, etc.; by Charles Darwin, F.R.S., F.G.S. 684 pp., 8vo, with 30 copper plates. 1854. London. Ray Society. —The volume by Mr. Darwin on the Lepadidæ or pedunculated Cirripedes, published in 1851, was noticed in a former volume of this Journal, and also his memoir on the Fossil Lepadidæ, published by the Palæontographical Society. We welcome with peculiar pleasure its successor which completes the subject. Mr. Darwin's works are the result of great labor and extreme care, and have a critical accuracy which entitles them to the highest confidence. In the work just issued, the anatomical structure of species of the different groups is thoroughly made out and much that is new presented. The nervous system is brought out complete, even to the nerves passing to the eyes. The remarkable peculiarities of the genera Cryptophialus and Alcippe, pedunculate Cirripeds, are well detailed. Mr. Darwin shows that the sexes are distinct as in Ibla and Scalpellum; while all the Balanidæ are hermaphrodites. We might cite largely from the work to the advantage of our readers, but refer them to the volume, which has the high value of giving figures of all the species, as well as good descriptive details.