nary bladder. Two ovaries. Heart consisting of a single auricle and ventricle. They may be distributed into two leading divisions; the cartilaginous, whose skeleton consists of cartilage; the bony, where it is formed of a more firm substance. (A) CARTILAGINOUS FISHES. Order I. Chondropterygii ; having no gill-cover; an uterus, with two oviducts. 1 Petromyzon, lamprey 2 Gastrobranchus 4 Squalus, shark, saw.fish 5 Lophius, sea-devil, frog.fish 3 Raia, skate, torpedo, stin- 6 Balistes, file-fish II. Branchiostegi; having a gill cover. 1 Accipenster, sturgeon, beluga 5 Cyclopterus, lumpsucker 2 Ostracion, trunk-fish 3 Tetrodon 4 Diodon, porcupine-fish 6 Centriscus 7 Syngathus, pipe.fish 8 Pegasus (B) BONY FISHES, divided according to the situation of their fins. Order I. Apodes; no ventral fins. 1 Muræna, eel kind 2 Gymnotus, electrical eel 3 Anarrhichas, sea-wolf 4 Xiphias, sword-fish II. Thoracici; ventral fins directly } Echeneis, sucking fish 2 Coryphæna, dorado 3 Zeus, dory 4 Pleuronectes, flounder, plaice, 5 Ammodites, launce 6 Ophidium 7 Stromateus 8 Trichiurus under the thoracic. 6 Sparus 7 Perca, perch 8 Scomber, mackarel, bonito, tunny dab, holibut, sole, turbot 9 Mullus, mullet, 5 Chæladon &c. &c. III. Abdominales; ventral fins behind the thoracic; chiefly in habit fresh water. 1 Cobitis, loach 2 Silurus 3 Salmo, salmon, trout, smelt 4 Esox, pike 5 Clupea, herring, sprat, shad 6-Cyprinus, carp, tench, gold fish, minow, &c. &c. IV. Jugulares; ventral fins in the front of the thoracic. 1 Gadus, hadock, cod, whiting, ling 2 Uranoscopus, stargazer 3 Blennius, blenny 4 Callionymus, dragonet The animals which have no vertebral column do not possess so many common characters as the vertebral classes. Their hard parts, when they have any, are generally placed on the surface of the body. The centre of the nervous system, instead of being inclosed in a bouy case, lies in the same cavity with the viscera. The oesophagus is generally surrounded by a nervous chord coming from the brain. Their respiration is not carried on by lungs; and they have no voice. Their jaws move in various directions. They have no urinary secretion. The invertebral animals were distributed by Linnæus into two classes; insects and worms, (vermes). The anatomical structure of these animals was very imperfectly known, when the Swedish natu ralist first promulgated his arrangement. But the labours of subsequent zoologists, and particularly those of Cuvier, have succeeded in establishing such striking and important differences in their forma. tion, that a subdivision of the Linnæan classes became indispensably necessary. The insects of Linnæus are divided into crustacea and insecta: and the vermes of the same author form three classes; viz. mollusca, vermes, and zoophyta. The mollusca derive their name from the soft fleshy nature of their body. This class includes those pulpy animals, which may either be destitute of an external covering, when they are called mollusca nuda, as the slug; or may be enclosed in one or more shells, as the snail, oyster, &c. when they are termed testacea. The animals of this class have no articulated members; they have blood-vessels, and a true circulation. They respire by means of gills. They have a distinct brain, giving origin to nerves; and a spinal marrow. 1 Sepia, cuttle-fish 2 Argonauta 3 Nautilus 4 Limax, slug 5 Aplysia 6 Doris 7 Clyo 8 Patella, limpet 9 Helix, snail 10 Haliotis, Venus's ear 11 Murex, caltrop, or rock-shell 12 Strombus, screw The Zoophytes have neither brain nor nerves; no heart, nor, per. haps, blood-vessels; no articulated members. Order I. Echinodermata; covered by a hard and tough coriaceous skin. IV. Inhabitants of corals, corallines, sponges, &c. The coral reefs that surround many islands, particularly those in the Indian Archipelago, and round New Holland, are produced by various tribes of these animals, particularly by the cellepora, isis, madrepora, milepora, and tubipora. The animals form these corals with such rapidity, that enormous masses of them very speedily ap pear where there were scarcely any marks of such reefs before. [Pantologia. CHAP. II. WORMS. Vermes.-Linn. SECTION I. Introductory Remarks. THE system of zoology that still continues most popular in our own country is that of Linnæus, and we shall hence make choice of it in the prosecution of the present work. Under this system the various classes of animals which it comprises may be contemplated in an ascending or a descending scale. Having commenced with inorganic matter, and meaning to close with the mechanical and other curious inventions of human intellect, we shall prefer the former of these views; and shall open with a few specimens of the lowest of the Linnæan classes, and which he has distinguished by the name of Vermes, or the Worm Tribes, the classific and ordinal characters of which we have already stated in the preceding chapter. [EDITOR. SECTION 11. Infusory Worms or Animalcules; Wheel-animal, Eel-vibrio, Trichoda, Monas. THESE Constitute a division of animals which until the latter part of the 17th century, had escaped all human attention and investigation, and constituted a kind of invisible world: a series of beings, the structure, powers, and properties of which, are perhaps more astonishing than those of most other animals: yet of such minute. ness as, in general, to elude the sharpest sight, unless assisted by glasses. The ancients therefore were totally unacquainted with this class of beings. To them the mite was made the ne plus ultra, or utmost-bound of animal minuteness; but the moderns, assisted by the invention of the microscope, have discovered whole tribes of animals, compared to which even mites may be considered as a kind of elephants. These minute beings are chiefly to be observed in fluids of various kinds; and principally in such as have had any animal or vegetable substances infused in them; and for this reason they are often called in modern zoology, by the title of animalcula infusoria, or infusorial animalcules. A most extraordinary idea was entertained by the celebrated Count de Buffon, relative to these animalcules; viz. that they were not real animals, but a kind of organic particles or moleculæ, which were capable, under certain circumstances, of being formed into animated beings. The experi ments of Spallanzani and others have, however, completely over. thrown this chimerical and absurd theory of the Count de Buffon; and indeed one would hardly think it possible for any person of unprejudiced mind, nay one may even add, of common sense, to view the several animalcules in fluids, and at the same time to doubt of their being real animals. Their rapid and various motions; their pursuit of the smaller kinds on which many of the larger prey; their avoiding each other as they swim; the curious and regular structure of their bodies; and their whole appearance, form the most convincing proofs of their real animal nature and life. Animalcules, as before observed, are most frequently found in fluids; but this is a doctrine that has not always been clearly under stood, and has been productive of some erroneous ideas in natural history. Some writers, for instance, have asserted that almost every kind of fluid abounded with animalcules; and that wines and spirits exhibited legions of them. This, however, is so very far from the truth, that none are ever to be discovered in inflammable spirits, or in any fermented liquor that has not passed either into the state of vinegar, or that is not grown completely vapid. As almost all extraordinary discoveries are liable, when related by unskilful persons, to have their circumstances exaggerated by additional ornaments, we need not be surprized that this has been the case relative to the history of microscopic animalcules. No sooner did the microscopical observations of Leewenhoeck and a few others |