In the fourth order, that of the Rodentia, the toes differ but little from those of the Carnivora, but there are no canine teeth, and the incisors are placed in front of the mouth, and adapted to a very peculiar sort of manducation. Then come those animals whose toes are much cramped and deeply sunk in large nails, which are generally curved; they have no incisors, and in some the canines disappear, while others have none of any description. We comprise them all under the title of Edentata. This distribution of the unguiculated animals would be perfect and form a very regular series were it not that New Holland has lately furnished us with a little collateral one, consisting of animals with pouches, the different genera of which are connected by a general similarity of organization; some of them, however, in the teeth and nature of their diet corresponding to the Carnivora and others to the Rodentia, and a third to the Edentata. The hoofed animals are less numerous, and have likewise fewer irregularities. The Ruminantia, by their cloven foot, the absence of true incisors in their upper jaw, and their four stomachs, form an order that is very distinct. The remaining hoofed animals may all be united in a single order, which I shall call Pachydermata or Jumenta, the elephant excepted, which might constitute a separate one, and which is remotely connected with that of the Rodentia. In the last place we find those of the mammalia which have no posterior extremities, whose piscatory form and aquatic mode of life would induce us to form them into a particular class, were it not that in everything else their economy is similar to that in which we have them. These are the hot-blooded fishes of the ancients, or the Cetacea, which, uniting to the vigor of the other mammalia the advantage of being sustained by the watery element, present to our wondering sight the most gigantic of animals. ZOOLOGICAL ZONES --SIR RICHARD OWEN Organic life in its animal form is much more developed, and more variously, in the sea than in its vegetable form. Observations of marine animals have led to attempts at generalizing the results; and the modes of enunciating these generalizations or laws of geographical distribution are very analogous to those which have been applied to the vegetable kingdom, which is as diversely developed on land as is the animal kingdom in the sea. Certain horizontal areas, or provinces, have been characterized by the entire assemblage of animals and plants constituting their population, of which a considerable proportion is peculiar to each province, and the majority of the species have their areas of maximum development within it. Of such provinces of marine life, that much-lamented, far-seeing, and genial philosopher, Edward Forbes, has provisionally defined twenty-five.