In the preliminary remarks on the nature of Organic Remains (_ante_, p. 43), the various conditions in which the durable structures of animals are preserved in the mineral kingdom, were fully explained; we may therefore at once enter upon the investigation of this most important division of our subject; that to which the term _Palæontology_, is, indeed, restricted by some authors. The fossil remains of the animal kingdom will be treated of under the following heads:-- I. Zoophytes: including-- 1. Porifera, or Amorphozoa: the most simple animal structures; as the _Sponges_. 2. Polypifera, or Polypiaria; _Coral-animals_. 3. Bryozoa, or _Molluscan Zoophytes_; as the _Flustræ_. II. Echinodermata, or Echinoderms; Comprising-- 1. Crinoidea; or Lily-shaped animals. 2. Asteriadæ; _Star-fishes_. 3. Echinidæ; _Sea-urchins_. III. Mollusca, or Mollusks. Under this head not only the fossil shells of testaceous mollusca, but also those of a lower order of animals, the _Rhizopodes_, or _Foraminifera_, will be treated of. 1. Foraminifera. 2. Bivalves: the Lamellibranchia, and Brachiopoda. 3. Univalves: the Gasteropoda and Pteropoda. 4. Cephalopoda; those with chambered shells, as the _Nautilus_ and _Ammonite_; and the naked tribes, the Sepiadæ, or _Cuttle-fish_. IV. Articulata. (Animals protected by a hard jointed envelope or case.) 1. Cirripedia: as the _Balanus_, or Barnacle. 2. Annelida: red-blooded worms, as the _Serpulidæ_. 3. Insecta, and Arachnida or _Spiders_. 4. Crustacea; including _Crabs_, _Lobsters_, _Trilobites_, &c. V. Pisces; or Fishes. VI. Reptilia; or Reptiles. VII. Aves; or Birds. VIII. Mammalia. IX. Man. CHAPTER VII. FOSSIL ZOOPHYTES.--PORIFERA OR AMORPHOZOA--POLYPIFERA OR CORALS--BRYOZOA OR MOLLUSCAN ZOOPHYTES. Many tribes of the extraordinary beings whose mineralized relics are the immediate subject of our investigation, have largely contributed to the solid materials of which the sedimentary strata are composed. In the most ancient rocks in which vestiges of organic structures have been detected, those of _Zoophytes_ hold a conspicuous place; and in the seas of tropical climates, the agency of the Coral-animalcules, or Polypifera, is producing enormous deposits, and laying the foundations of new islands and continents, and forming reefs of rocks hundreds of miles in extent, which, if elevated above the level of the sea, would rival in magnitude the mountain-chains of modern Europe. The reader unacquainted with the natural history of these marvellous creatures will find an account of their nature and economy, and of the physical effects produced on the earth's surface by their agency, in the sixth lecture of _Wond._ vol. ii. p. 588.