Two varieties of seals were seen in Belgica Channel--the Weddell seal (_Leptonychotes weddelli_), frequently met in small bands, and the crab-eater seal (_Lobodon carcinophaga_), which is more scarce. Among the _Cetacea_, the _Megaptera boöps_ (?) is met in large troops, often in the company of a large balænoptera (_Balænoptera Sibbaldii_) (?), but no genuine black or Greenland bone whale was ever seen. The littoral fauna and flora are badly represented on account of the constant motion of the ice along the rocky shores of the sea. Sea-wracks cannot fix themselves upon them, nor can animals. Yet in some well-sheltered crevices I found some rare sea-grasses (_Desmarestia_, etc.), and patellæ with small inferior animals. The first biological example we could ascertain, during our imprisonment of thirteen months in the ice-pack, was a general presence of diatomaceæ on the superficial sheets of the sea, as well as upon icebergs and in the interior of the holes and cracks of the sea-ice. The most frequently represented species are _Chætoceros_, _Coscinodiscus_, and _Chorethron_. The bed or plant is not very rich and but little varied. It is composed of small-sized animals, of which the most frequently represented are enumerated in the order of their frequency: the _Copepodaes Radiolaria_ (_Protocystis_, _Cannosphæra_), _Pteropoda_ (_Limacina_), _Polychæta_ (_Pelagobia_), _Copelata_ (_Oikopleura_), _Ostracoda_, _Siphonophora_ (_Eudoxia_), etc. The size of the bed or plant undergoes a season’s change. During the winter, sea-ice, being very thick, intercepts daylight; in consequence the diatomaceæ cannot increase and the bed decreases considerably in size. In the summer, on the contrary, sea-ice thins, cracks, and tracks are numerous; light can thus penetrate, which accounts for an abundant growth of diatomaceæ, and the bed increases considerably in volume. One of the most important _plancton_ forms or plants, with regard to the part it plays in the economy of antarctic life, is a species of the _Euphausia_ kind. In fact, there exist immense shoals of this animal under the ice-pack, and these shoals serve as an almost exclusive food for seals, penguins, and presumably cetaceans.