It may easily be conceived, that in a sea-voyage a naturalist has fewer opportunities of enriching his collection, than when travelling by land; particularly if the vessel is obliged to pass hastily from one place to another, with a view to her arriving at her destination within a limited period. During our three years' voyage, little more than the third of our time was spent on shore. It is true, that curious animals are occasionally found in the open sea, and that a day may be pleasantly passed in examining them; but it is also true, that certain parts of the ocean appear, near the surface, to be almost wholly untenanted; and accordingly a passage of eleven weeks produced only ten species of animals: these, however, being met with only at sea, are still but partially known to the naturalist, and were the more interesting to me, as, during the preceding voyage, I had become acquainted with many remarkable productions of the ocean. My best plan will be, to arrange in a chronological order all the zoological observations which offered in the course of this voyage. The first, then, was the result of a contrary wind, by which we were detained much longer than we intended in the Baltic, and thus enabled to use our deep fishing-nets upon the great banks: these brought to light a considerable number of marine animals. Upon the branches of the _spongia dichotoma_, some of which were twelve inches in length, sat swarms of _Ophiura fragilis_, _Asterias rubens_, _Inachus araneus_, _I. Phalangium_, _I. Scorpio_, _Galathea strigosa_, and _Caprella scolopendroides Lam._ We obtained, at the same time, large pieces of _Labularia digitata_, _Sertularia abietina_, upon which nothing of the animal kind was to be seen, but attached to which was frequently found _Flustra dentata_; also _Pagurus Bernhardus_, _Fusus antiquus_, _Rostellaria pes pelecani_, _Cardium echinatum_, _Ascidia Prunum_, _Balanus sulcatus_, _Echinus saxatilis_, and _Spatangus flavescens_. Two different species of _Actiniae_, seated on stones, were brought up, which were not to be found either in _Pennant's British Zoology_, or in the _Fauna danica_.