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class have naturalists arranged them into orders? 4. Describe the first order of mammalia,-second, &c. 5. What are the orders of mammalia according to Linnæus? [NOTE. The distinctive characters of the Linnæan orders of mammalia, with the exception of the last, depend on the kind, position, and number of the teeth, and thus animals of very different habits were brought together, from a resenblance in one comparatively unimportant particular.]

LESSON 97.

Birds.

Ornithology, that branch of natural history which describes the structure, economy, habits, &c. of birds.

Vis'cid, glutinous, tenacious.

THE immense catalogue of the species of birds, and the variety and beauty of their external characters, have made them favourite objects of investigation with the natural historian. The extraordinary degree of instinct displayed in all their habits and economy, more especially in the construction of their nests, the care of their young, and the conduct of their migrations, have called forth the admiration of the philosopher and the lover of nature. The splendid colouring of their plumage, the powers of melody, and the liveliness and docility of many species, have given them value as objects of beauty and entertainment.

The class of birds is divided, according to their structure and habits of life, into six orders. Birds of prey, or rapa cious birds (accip'itres) correspond, in many respects, with the carnivorous animals among quadrupeds. They are distinguished by their strong, hooked beaks, and their crooked and powerful talons. They are particularly remarkable for the very great distance at which they perceive their prey, and the accuracy with which they direct their flight towards it. Besides the upper and under eye-lids, all birds have a third which is semi-transparent, and serves the purpose of protecting the eye from the contact of external bodies, or from too powerful light, whilst at the same time it does not prevent them from distinguishing the objects around them. This membrane is situated at the inner angle of the eye, and is drawn over the globe of it, like a curtain, at will. It

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is by means of this protection, that the eagle is enabled to look steadily at the sun.

Sparrows (Pas'seres) form the most extensive and numerous order, embracing a great variety of species, which differ so much among themselves, as to be hardly capable of an intelligible description, common to them all. To this order belong those species which are most celebrated for the sweetness and harmony of their notes; and in general the organ of voice in them is larger and better formed, than in any others. Among them are the robin, the swallow, the linnet, the humming-bird, and the nightingale.

The third order (Scanso'res, Climbers) includes those birds that have the external toe upon each side turned backwards, which enables them to grasp substances more firmly, and affords them a more sure support, than other birds. Among them are the woodpecker, the cuckoo, and the parrot. Woodpeckers are furnished with a long and slender tongue, covered towards its tip with spines or bristles, which are turned backwards, and coated with a thick viscid secretion. They run in every direction around the trunks and branches of trees, striking them with their beaks, and thrusting their tongues into holes and clefts, for the purpose of drawing out their food.

The Gallinaceous birds (Gallina'cea) have short and weak wings, and, of course, they are not constructed for long and continued flight. Of this order are the peacock, the turkey, the pigeon and the common fowls. The pigeons form in some particulars an exception to the general characteristics of their order. They fly very well, live in pairs, and build their nests upon trees or in the clefts of rocks. The most remarkable species among them is the crowned pigeon of the Molucca islands, which is equal in size to a turkey. Its voice is exceedingly loud and harsh, and is said to have frightened sailors who landed on the islands which it inhabits, by its resemblance to the yells of the savage natives.

The Waders (Gralla,) otherwise called shore birds are distinguished by their very long and naked legs, which permit them to wade to a considerable depth in the water without wetting their feathers. All birds with this structure are not, properly speaking, waders in their habits, though they are ranked in this order. Among them are the heron, plover, oxeye, and ostrich. The ostrich is almost incapable of

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flight, but runs with immense rapidity. Its height varies from six to eight feet; it is the most lofty of birds and the swiftest of all animals.

The toes of Web-footed birds (An'seres,) are connected together by a membrane, which fits them for being used as oars. Their whole structure is such as to adapt them for swimming; their legs are situated far back upon their bodies, their feathers are thick, smooth and oily, and their skin beneath covered with a layer of close down, which effectually protects them from the contact of water. Most of them are capable of lofty and long continued flight, as the wild goose and duck; whilst others from the shortness of their wings can scarcely raise themselves into the air, but are principally confined to the surface of the water.

As quadrupeds cast their hair, so all birds every year ob tain a new covering of feathers; this is what is termed moulting. During its continuance, they always appear sickly and disordered; no feeding can maintain their strength, for their nourishment is now consumed and absorbed in administering a supply to the growing plumage. It is worthy of observation, that of the vast number of birds which inhabit, the globe, it has never been discovered that a single one is of a poisonous nature. They differ very much in being more or less salutary and palatable, as an article of diet; but none of them are pernicious. Sea-faring people and travellers eat every species of egg without the smallest hesitation.

QUESTIONS.-1 What renders birds objects of interest to the naturalist and philosopher? 2. Describe the first order of birds. 3. Second. 4. Third. 5. Fourth. 6. Fifth. 7. Sixth. 8. What is said of their moulting? 9. What is worthy of observation respecting them? 10. What are the Linnæan orders of birds? (see Appendix.)

LESSON 98.

Reptiles and Fishes.

Icthyology, that branch of natural history which treats of fishes. REPTILES have less intelligence, fewer faculties, and less instinct, than either quadrupeds or birds. They are, in general, sluggish and indolent in their habits of life, and obtuse in their sensations. In cold countries they pass the greater

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part of the winter in a dormant state. They are arranged in four orders. The Tortoises (Chelo'nia) have a covering consisting of an upper and under shell, joined at their sides into one, which permits only their head and other extremities to be extended without it. They have no teeth but their jaws are armed with a tough horny substance which supplies their place. The order of Lizards (Sau'ria) includes a very considerable variety. The greater part of them have four feet, but a few are possessed of only two. They have nails and teeth, and their skin is covered with scales. Among them are the crocodile, the alligator, the chameleon, the true lizards and the dragons. The crocodile

is the most celebrated. It is from twenty to thirty feet in length including the tail, and is covered with a coat of scales, which on the back form an armour proof against a bullet, and have an appearance like that of carved work. The Serpents (Ophidia) are distinguished by their long and slender bodies without limbs, and by the great extensibility of their jaws, mouth and throat. They are divided into the venomous and those that are not venomous. The number of the latter is the greatest and includes the largest animals. The venomous serpents are generally armed with fangs for the specific purpose of infusing poison into the wounds they inflict. When the tooth pierces the flesh of any animal, the poisonous fluid is injected into the opening. When broken or injured, these fangs are renewed, and when not employed, are hidden from the sight by a fold or projection of the gum. Serpents cast their skins annually, and the beauty and lustre of their colours are then highly augmented. The reptiles of the fourth order (Batrach'ia, frog, salamander, &c.) are principally remarkable for a transformation which takes place in their offspring after leaving the egg. When first hatched, they are strictly an aquatic animal, and capable of breathing and living only under water. In this state they are seen by thousands, of a dark colour, with round bodies, swimming about in brooks and small ponds. After a certain period, their form and structure are altered, and they become at once animals capable of breathing only in air.

Fishes being destined to inhabit only the water, are provided with organs and a structure adapted to the element in which they reside. Since they cannot breathe pure air, they

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have a peculiar modification of the organs of respiration and circulation. A current of water is constantly passed over the gills by the action of the mouth of the animal, and by means of the air it contains, exerts an influence over the blood circulating in them, and produces the same changes in it as are produced in the lungs of other animals by the air they breathe. A few fishes, one of which is called the torpedo, are possessed of a very remarkable means of defence, which consists in the power of inflicting upon whatever living creature comes in contact with them, a powerful electrical shock. These shocks are so powerful, that in South America, horses driven into the pools which some fishes of this kind inhabit, have sometimes been stunned and even killed. The shocks become weaker and weaker upon continued repetition, till the animal is exhausted, and loses for some time the power of producing any effect.

QUESTIONS.-1. What is said of reptiles? 2. Describe the first order. 3. The second. 4. The third. 5. The fourth. 6. Describe the organs of respiration and circulation in fishes. 7. What remarkable means of defence have some fishes? [NOTE. Fishes are divided into orders and genera, according to certain differences in the formation, structure, and situation of their mouth, gills, gill-coverings, fins, &c. and they are called Apodes, as eels; Jugulares, as cod; Tho racici, as perch; Abdominales, as pike and salmon.]

LESSON 99.

Structure and Transformation of Insects,

Fa'cet a little face or side of a body cut into a number of angles.
Hexagonal, having six sides, or angles.

Lubricated, made smooth so as easily to glide over any part.
Entomology, that branch of natural history which treats of insects.

THE animals of this class are remarkable for a greater variety of powers and a more wonderful display of instinct and intelligence, than any other of the invertebral animals. They are distinguished by many peculiarities of form. Instead of a heart, insects have a vessel or reservoir situated along the back, extending from one end of their bodies to the other, and filled with a transparent fluid, which is supposed to answer the purpose of blood, and to be conveyed, by absorption, to the various organs. They have no parti

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