Coal-land, although more rich, in general, than any other in vegetable fossils, is not the only one which contains them; the secondary formation, and the tertiary present also numerous impressions of leaves, of branches, of flowers even and of fruits, whose succession at different epochs of formation, and comparative structure in various countries of the world is not less interesting. Their acquisitions cannot be too strongly recommended; but it is necessary, as much as possible, to join to these fossils, the animal fossils which may accompany them, which will better tend to determine the epoch of the formation of the deposit which contains them. There is still another class of vegetable fossils which, in later times, has acquired more importance than has been given to them before; they are petrified woods which by a new process of preparation, permit to study their interior organisation, and to compare them to living woods; these woods are found in the deposits of every epoch, and in countries the farthest separated. They belong to families and classes very different; thus their examination is very important. It should be recommended to persons, who encounter them, to collect them with great care, in choosing pieces which appear to differ, not so much by their exterior form as by their interior structure. It is not necessary to send large samples of the characteristics which distinguish them as regards their interior structure and especially for the dicotyledonous woods with concentric layers; it is best, on the contrary, to break them neatly with the hammer and to reduce them about 1 decimetre cube. The only large pieces which ought to be preserved are those of the monocotyledons, which as the woods of palms and the woods which would be analogous to the trunks of the tree ferns, for there it is necessary, as much as possible, to have the trunk entire from the centre to the surface and in length of 2 to 3 decimetres. Among places where the most remarkable and varied fossil woods have been found, we would cite the little Antilles, above all Antigua, Saint-Lucy and the Martinique. The museum possesses but few specimens from these places. All the specimens of fossil plants, which may be addressed to the museum, should be wrapped with care, in two or three papers; those which have delicate impressions should be covered in their face with cotton or lint, above all if the rock or stone is tender; if the samples are thin and fragile, as often arrives with impressions upon slates, they should be placed in separate boxes. The boxes should be proportionate to the size of the samples, so as to be filled compactly that they may not be shaken in transportation; fossil should not be put in the same case whith dried plants or glass cases. Without these precautions the samples would rub and the impressions be effaced. CHAPTER III. ZOOLOGY.