Cryptozoology, as the name implies, is the scientific classification and study of creatures that may or may not exist-a discipline frequently relegated to the margins of the scientific establishment. So Coleman and Huyghe's decision to write about the Loch Ness Monster ("Nessie"), Giant Beavers and Mystery Mantas hardly seems like an ideal step in the journey towards academic legitimacy. Nonetheless, the rare victory that comes with the "official" recognition of a once-dubious aquatic creature (a giant squid, say, or a megamouth shark) has emboldened the authors to attempt the definitive guide to the elusive "mystery creatures" that might populate over two-thirds of the planet's surface. Unfortunately, the authors' focus is primarily taxonomic rather than narrative or expository, which makes for a disappointingly dull read. Plodding through a detailed animal-classification system quickly becomes a bit, er, dry, so readers looking for lively nature stories would be wise to avoid this particular volume, as the quasi-mythological nature of its subject does little to spice things up. Even such unlikely beasts as Great Sea Centipedes or Waterhorses (of which Nessie may be the most well-known example) are handled primarily in such clinical terms as size, range and likely habitat, supplemented with brief and surprisingly dreary "descriptive incidents" and eyewitness accounts. Heavy on methodology and light on the mystery and excitement of the best nature writing, this book may spark in readers the sense that the authors were more worried about the criticism of their peers than about the drowsiness of their readers. Illustrations.