 Borrowing an analogy from publishing and bookbinding, he divides whales into three "books", called the Folio Whale (largest), Octavo Whale and the Duodecimo Whale (smaller), represented respectively by the sperm whale, the orca (which he calls the "grampus") and the porpoise.Each such book is then divided into "chapters" representing a separate species.By the current taxonomy of "Cetacea", the classification in "Moby-Dick" is inaccurate and incomplete as well, presenting only a fraction of the nearly ninety species of Cetaceans known today.