When, in 1743, the news of the discovery of Behring Island reached Kamtchatka, several expeditions were fitted out for the purpose of hunting the sea-cow and the various fur-bearing animals, such as the sea-otter, fur seal, and blue fox, which are found there; and very soon many whaling vessels began to stop there to lay in a supply of sea-cow meat for food. So great was the destruction wrought by these whalers and fur-hunters that in 1754, only thirteen years after its discovery, the sea-cow had become practically exterminated. In 1768, according to the investigations of Dr. L. Stejneger of the U. S. National Museum, Washington, who has made a most careful study of the question, this large and important marine mammal became wholly extinct, the last individual ever seen alive having been killed in that year; and the fate which overtook Rhytina so speedily has almost become that of the buffalo, and will as certainly become that of the fur seal unless it be protected. It may interest the reader, especially if he be a traveller, to know that, besides the fine specimen of Rhytina in the Natural History Museum, already alluded to, good skeletons are possessed by the Museums of St. Petersburg, Helsingsfors (Finland), Stockholm, U. S. National Museum, Washington, as well as portions of skeletons by other museums. The Sirenians are an ancient race, for their remains have been found in Tertiary strata, of various ages, from Eocene to Pleistocene, over the greater part of Europe--in England, Holland, Belgium, France, Germany, Austria, and Italy; also near Cairo. In the New World, fossil Sirenians have been found in South Carolina, New Jersey, and Jamaica. Another European species is the Halitherium, from the Miocene rocks of Hesse-Darmstadt, of which a cast may be seen in the Natural History Museum, South Kensington. Its length is 7 ft. 8 in. The teeth in this form resembled those of the Dugong. The Rhytina was probably intermediate between the Dugong and the Manatee, judging from the casts of its brain-cavity. Its brain was very small considering the size of the animals. Altogether, as many as fourteen fossil genera and thirty species are known. Evidently, then, the old Sirenia were once a much more flourishing race. At present, they are confined exclusively to the tropical regions of the earth, and their past distribution, as revealed to the geologists, adds one more proof to the now well-established fact, that throughout most of the Tertiary era the climate of northern latitudes was very much warmer than now--in fact, sub-tropical. What cause, or causes, brought about so great a change, we cannot stay to consider here.