LUSCA.
Those animals which are called WORMS by Cuvier, have a very imperfect structure, but they are also supe rior to insects, in possessing a sanguiferous system. Their bodies are divided into rings, and they have no distinct head. They have, however, a mouth, which is often furnished with teeth, a sanguiferous system, and some of them have evident respiratory organs or bran chix. They are distinguished into two orders, the first containing those worms that have external organs of res piration, and the second such as have no such organs.
See HELM1NTHOLOGY.
The ZOOPHYTES are the lowest class of animated na ture. They have no vessels, no nerves, scarcely any or gan of sensation, and often consist only of a simple tube furnished with tentacula. They are either free, or at tached to a solid trunk. The former consist of four or ders, viz. echinodermata, that are inveloped in a calca reous covering, and have the intestines floating within its cavity ; sea-nettles, having a fleshy or gelatinous cover ing, and the intestines adhering to the body ; kfusoria or animalcules, that are extremely small, and float in certain liquors ; and polypi, having a gelatinous body in creasing by shoots. Those Zoophytes which are attach
ed to a solid trunk, consist of five orders, viz. Zoo PHYTES properly so called, having a medullary substance traversed by a horny substance, and terminated by polypi at the branches ; Escara, having each polype con tained within a horny or calcareous cell, without any cen tral axis ; Ceratophyta, having a solid axis, covered with a sensible fleshy substance, from the hollows of which polypi occasionally appear ; Lythophita, having an axis or stony base, the hollows of which serve as receptacles to polypi ; and Sponges, having a base that is spongy, and friable or fibrous. See ZOOPHYTOLOGY.
After these preliminary observations, we proceed to our comparative view of the several organs as they ap pear in the classes and orders of animals which we have eatablished, reserving any particular account of certain peculiarities of structure that are found in various tribes or species, for the articles of Zoology under which the classes that contain these tribes or species are de scribed.