Now in a paperback edition, America's greatest literary naturalist takes readers on the ultimate wildlife safari: a true back-of-beyond voyage to the world's most unforgiving land, the islands off Antarctica's northern ice shelf, and to that second most remote place on earth, South Georgia Island, ''the last outpost in a great emptiness of ocean.'' Matthiessen has once again lit upon a subject profoundly fitted to his creative genius. He is simply the ultimate lyricist of loss, a writer brilliantly attentive to the way vanishings are braided into even the most exquisite moments of our lives. He agonizes over what is passing away, but does so in a manner that increases our appreciation of what remains. In ''End of the Earth,'' Matthiessen joins the crew of the Akademik - a 384-foot research vessel bound for wild and storied South Georgia Island and Antarctica. Along the way we are treated to a patented Matthiessen brew: lyricism and emotion applied to the sharp-eyed evaluations of a seasoned naturalist. Brilliant and instructive observations of the creatures inhabiting this far-flung region are sprinkled with eloquent disquisition on the history of the region (Shackleton, Captain Cook,