The terrestrial animals, properly so called, are represented by a small species of _Diptera_ with rudimentary wings, podurellæ in large quantities, living with three or four species of small _Acarida_ or mites among mosses and lichens. Upon soft water-wracks there rises a microscopic fauna composed of _Nematoidea_, _Rotifera_, _Tardigrada_, _Infusoria_, and _Rhizopoda_. These animals and plants represent at the present day the terrestrial antarctic fauna and flora, and no other living animal has yet been discovered upon the whole extent of the properly called antarctic region, for we cannot consider as terrestrial animals the birds and seals which inhabit this region. The question is to know what has become of the autochtone fauna and flora, which must have inhabited the great antarctic land and wastes during the geological periods, when the ice had not invaded the polar regions. To this question, it seems to me, there is but one answer to be made. The whole terrestrial antarctic fauna was destroyed during the glacial epochs, which, before the present epoch, covered over with ice more completely than to-day the whole antarctic region. We possess decisive information concerning the existence of a vast crystalline cap which stretched over the whole of Patagonia and Tierra del Fuego. Moreover, we observed in Belgica Channel some glacial phenomena which incontestably indicate a much greater extension of ice than the present existing one. I believe that even the plants and terrestrial animals that were found upon the lands of Belgica Strait are not the remains of the antarctic flora and fauna of the preglacial epoch, but American immigrants brought by the large-winged birds which are common to both regions. Birds are very numerous in the Belgica Channel, and the greater part of them rest in the holes and cracks of the cliffs. With but one exception, the _Chionis alba_, all are web-footed and are a part of the orders _Gavia_, _Tubinares_, _Steganopoda_, and _Impenes_. The most common are the Dominican sea-gull (_Larus dominicanus_), the brown sea-gull (_Megalestris antarctica_), the sea-swallow (_Sterna hirundinacea_), the large petrel (_Ossifraga gigantea_), the bird of tempests (_Oceanites oceanicus_), the Cape pigeon (_Daption capensis_), the carunculated cormorant (_Phalacrocorax carunculatus_), the Papuan penguin (_Pygoscelis papua_), and the antarctic penguin (_Pygoscelis antarctica_), these latter two living in vast rookeries; in short, the curious beak-sheathed bird (_Chionis alba_) which, like most other birds already mentioned, nests in the holes and crevices of rocks.