We shall first allude to some crustaceans named Cirrhipedes by Lamarck. The metamorphoses which they have undergone since they left the egg have so much changed them, that Cuvier and all the 54 zoologists of his age placed them in the class of mollusca. The incrustations of their skin resembled shells, which these creatures generally carry in the substance of their mantle. These ambiguous creatures are far from being microscopic; there are Balani which attain the size of a walnut, and some have been found not less than ten inches high, as the _Balanus psittacus_. Some years since we saw on a piece of floating wood, found by fishermen in the North Sea, Anatifæ on the end of stalks from six to seven feet in length. The anatifæ themselves were of the usual size. These cirrhipedes belonged to every geological period; they have already been found in the Silurian formation, but, unlike the trilobites their contemporaries, they pass through all the ages, and, far from decreasing, they reign as masters at the present time in the two hemispheres. It was an English naturalist, Thomson, who first made known the true nature of these singular organisms. So far were many from understanding their affinities with the other classes, that even after the excellent researches of the Belfast naturalist, they doubted their correctness, and supposed that these animals were allied both to the mollusca and to the articulata. We see by this the immense progress which embryological studies have caused us to make in the appreciation of natural affinities. No one at the present time, who has seen a cirrhipede hatched, can retain any doubt as to the place which it ought to occupy. These crustaceans, taken as a whole, lead a life in which we find more than one 55 contrast; all live as wanderers when they first leave the egg, and they are hatched in such abundance on the coast, that the water becomes literally troubled with them. At the first period of their life, they have a supple and elegant body, and fins admirably divided, and the gracefulness of the postures which they assume does not yield in beauty to those of the most brilliant insect. After having spent some time in seeking adventures, they are seized with disgust for a nomad life; they choose a resting-place, and establish themselves by means of a cable which they afterwards abandon, and shelter themselves in an enclosed retreat for the rest of their days. Many cirrhipedes choose the back of a whale or the fin of a shark, and make the passage across the Atlantic or the Pacific in less time than the swiftest steamboats.