Just about a century ago a great animal disappeared from the ocean, which, according to Owen, was contemporary with the fossil elephant and rhinoceros of Siberia and England. Steller, a Russian voyager and naturalist, discovered the creature, afterward called _Stelleria_ by Cuvier, in Behring's Straits; a huge, unwieldy whale-like animal, one of the marine pachyderms, allied to the Manatee, but much larger, being twenty-five feet long, and twenty in circumference. Its flesh was good for food, and from its inertness and incapacity for defence, the race was extirpated in a few years. Steller first discovered the species in 1741, and the last known specimen was killed in 1768. It is believed to be quite extinct, as it has never been met with since. Nearly a century ago, Sonnerat found in Madagascar, a curious animal, (_Cheiromys_,) which in structure seems to connect the monkeys with the squirrels. So rare was it there that even the natives viewed it with curiosity as an animal altogether unknown to them; and, from their exclamations of astonishment rather than from its cry, the French naturalist is said to have conferred upon it the name of Aye-aye, by which it is now known. _Not a specimen, as I believe, has been seen since Sonnerat's day_, so that, if not actually obliterated, the species must be on the verge of extinction. Species are dying out in our own day. I have already cited the interesting case of the Moho, that fine Gallinule of New Zealand, of which a specimen--probably the last of its race,--was obtained by Mr Walter Mantell; and that of the Káureke, the badger-like quadruped of the same islands, which was formerly domesticated by the Maoris, but which now cannot be found.