Lying some 250 miles off the east coast of Africa, Madagascar is the world"s fourth-largest island. It is quite unlike the neighboring continent, and, for that matter, quite unlike any other landmass on the planet. Its plant life is almost wholly endemic: eight out of 10 plants there grow naturally only on Madagascar, and it has an entire ecosystem, the spiny desert, that is found nowhere else on earth. Many of its animal species, too, seem to have emerged from some evolutionary track that runs parallel to the rest of the world"s; here can be found lemurs that will fit into a human palm, dwarf hippos, giant chameleons, and other rarities. These plants and animals constitute an extraordinary diversity, writes science journalist Peter Tyson in this engaging book, and the island"s richness of life has long intrigued scientists, who have proposed several theories to explain it. Those scientists, some of whom Tyson profiles at work in the field, are racing against time to catalog island life before it disappears, for Madagascar"s human population is rapidly growing, and with that growth, the island"s forests and other habitats are falling. The urgency may abate, Tyson writes, with guarded optimism, now that the island"s current president has proposed that all of Madagascar be considered as a United Nations World Heritage Site, which would help provide funds to prevent further loss of habitat and diversity. Though this proposal is controversial, Tyson makes a good case for why it should be taken up--and he shows just how high the stakes are. Throughout his narrative, Tyson mixes scientific reportage with a nicely rendered travelogue that guides readers across the island while outlining key concepts of island biogeography and conservation biology. His book is a worthy companion to David Quammen"s Song of the Dodo, and valuable reading for anyone concerned with the world environment. --Gregory McNamee