The Guana is a species of the Lacerta, or Lizard tribe; under which genus is included all the varieties of crocodiles and alligators. The great American Guana is generally of a green colour; its back exhibits the appearance of a saw, and it is distinguished by a pouch under the throat, which it is able to expand or contract at pleasure, and which gives it an appearance truly formidable. It is, however, perfectly inoffensive. It inhabits rocks and woods, and subsists on vegetable food, as well as on certain species of insects. It deposits its eggs in the earth, where they are hatched by the heat of the sun; they are remarkable for having no testaceous covering, and are much valued for food.