The Aves, or Birds
Lay eggs from which their young are hatched by what is called incubation. Their skins are covered with feathers; and their jaws are horny, without teeth. Their blood is warm, and circulates like that of the mammalia. The six orders of Aves are as follow:—
1. Raptores, or birds of prey. These birds are distinguished by a very strong and sharp bill more or less curved, but always hooked at the extremity of the upper mandible, which is covered at the base with a kind of skin called the cere. The nostrils are usually open. The legs are very strong, the feet are large, and the toes, which are four in number, are armed with very strong, sharp, curved claws. The principal raptorial birds are the vultures, including the condor; the falcon family, including the eagles, hawks, kites, and buzzards; and the owls.
2. Insessores, or perching birds. These birds have all feet formed for perching, the hind toe springing from the same place as the other toes, which gives them great power of grasping. Their legs are of moderate length, and their claws not sharply curved. This order includes the thrushes, nightingales, and all the finest songsters of our groves, with the robin-redbreast, the sparrow, and other birds seen about dwellings, the swallows, the larks, the crow family, the kingfishers, the birds of paradise, and the humming birds.
3. Scansores, or climbers. These birds have two toes before and two behind. This construction gives them such great power of climbing, that they can ascend the perpendicular trunk of a tree. The principal birds in this order are the parrots, the cuckoos, and the woodpeckers.
4. Rasores, or gallinaceous birds. These birds have the head small in proportion to the body. The bill is generally short, with the upper mandible somewhat curved. The nostrils have usually a protecting fleshy membrane. The tarsus, or lower part of the leg, is long and bare, and there are four toes, those in front being united by a slight membrane, while that behind is generally higher up the leg, and smaller than the others. This order comprises most of the birds used as food, and includes the peacock, the turkey, the common cock and hen, the partridge, the pheasant, and the pigeon family.
5. Grallatores, or Waders. These birds are characterised by their long and slender legs, and by the thighs being more or less bare. There are three anterior toes, more or less united at the base by a membrane, or rudimentary web. The hind toe is wanting in some members of the order. This order contains the ostrich family, the bustards and plovers; the cranes, herons, and storks; and the snipes and woodcocks.
6. Palmipedes, or web-footed birds. These birds have the legs and feet short, and placed behind, with their fore toes united by a thick and strong membrane. The neck is much longer than the legs, and their bodies are covered with a dense layer of down beneath the outer plumage, which is close, and imbued with an oily fluid that repels the water. The principal birds in this order are the grebes, the auks and penguins, the petrels, the pelican and cormorant and the swans, ducks, and geese.
By many ornithologists the pigeons and ostriches are considered to form distinct orders, called respectively Columbæ and Cursores.
THE REPTILIA,
Or Reptiles, have neither hair, wool, nor feathers, and their bodies are either naked, or covered with scales. Some lay eggs, and some bring forth their young alive. Some have gills, and others lungs, but the latter have only a portion of the blood passing through them; and thus the blood of reptiles is cold, as it is respiration which gives the blood heat. The senses of reptiles are dull, and their movements are either slow or laborious. The following are the four orders into which this class is divided:—
1. Chelonian Reptiles. These animals have four legs. The body is enclosed in an upper buckler, called the carapace, and an under one, called the plastron. They have lungs which are much expanded; but they have no teeth, though they have hard horny jaws. The females lay eggs covered with a hard shell. The principal animals belonging to this division are the tortoises, which live on land or in fresh waters, and the turtles, which inhabit the sea.
2. The Saurian Reptiles. These animals have also expanded lungs, and generally four legs, but some have only two. Their bodies are covered with scales, and their mouths filled with teeth. This order includes all the crocodiles and lizards. The crocodiles have broad flat tongues, attached throughout to the jaws, and the lizards have long narrow tongues, which many of them can extend to a great distance from the mouth.
3. The Ophidian Reptiles are the snakes and serpents. The body is covered with scales, but it is destitute of feet. The lungs are generally well developed, only on one side. Serpents are frequently furnished with poison-bags at the base of some of their teeth.
4. The Batrachian Reptiles include the frogs and toads. The body is naked. The greater part of these reptiles undergo a transition from a fish-like tadpole furnished with gills to a four-legged animal with lungs. Others never lose their gills, though they acquire lungs, and of this kind are the siren and the proteus.
THE PISCES,
Or Fishes, are defined by Cuvier to be vertebrated animals with red blood, breathing through the medium of water by means of their branchiæ or gills. To this definition may be added, that fishes have no neck, and that the body generally tapers from the head to the tail; that most of the species are furnished with air-bladders which enable them to swim; and that their bodies are generally covered with scales. The heart has only one auricle, and the blood is cold. The gills require to be kept moist to enable the fish to breathe, and as soon as they become dry, the fish dies. Thus fishes with large gill openings die almost as soon as they are taken out of the water; while those with very small openings, like the eel, live a long time. Fishes have no feet, but are furnished with fins. The scientific knowledge of Fishes is called Ichthyology. Fishes are first divided into two great series, viz. the Bony Fishes, and the Cartilaginous Fishes, and these are again subdivided into nine orders, as follows:—
Osseous or Bony Fishes.
1. Acanthopterygii, or fishes with hard fins.
2. Malacopterygii abdominales, or soft-finned fishes, with the ventral fins on the abdomen behind the pectorals.
3. Malacopterygii sub-brachiati, or soft-finned fishes, with the ventral fins under the gills.
4. Malacopterygii apodes, or soft-finned fishes, without ventral fins.
5. Lophobranchii, or fishes with tufted gills.
6. Plectognathii, or fishes with the upper jaw fixed.
Chondropterygii, or Cartilaginous Fishes.
7. Cyclostomi, or fishes with jaws fixed in an immovable ring, and with holes for the gills.
8. Selachii, or fishes with movable jaws and holes for the gills.
9. Sturiones, with the branchiæ in the usual form.
Of the bony fishes the Acanthopterygii, or fishes with hard spiny fins, are divided into fifteen families, the principal of which are the perch family, the mailed cheek fishes, including the gurnards, the flying fish of the Mediterranean, and the sticklebacks, or jack banticles; the mackerel family, including the tunny, bonito, and sword-fish; the pilot-fish, the dolphin of the Mediterranean, so celebrated for the beauty of its dying tints, and the John Dory. Among the Malacopterygii abdominales, or soft-finned fishes, that have their ventral fins suspended from the abdomen, the most interesting are the carp family, the pike family, the flying-fish of the ocean, the salmon family, and the herring family, including the sprat, pilchard, and anchovy.
The Malacopterygii sub-brachiati are soft-finned fishes, with the ventral fins beneath the pectorals; the principal of which are the cod family, including the haddock, whiting, and ling; the flat-fish family, including soles, turbots, plaice, and flounders; and the suckers or lump-fish.
The Malacopterygii apodes are confined to the eel family.
The Lophobranchii include the pipe fish, and other fishes of similar form.
The Plectognathi comprise the very singular forms of the balloon-fish, the sun-fish, and other similar fishes.
The Chondropterygii, or Cartilaginous fishes, are divided into three orders, viz. the Sturiones, or sturgeon family; the Selachi, or sharks and rays, including the torpedo; and the Cyclostomi, or lamprey family. The last two orders were included by Cuvier in a single one.
THE MOLLUSCOUS ANIMALS
Have no bones except their shells. Their sense of feeling appears to be very acute, but the organs for the other senses are either wanting or very imperfect. The blood is cold and white, and the heart often consists of only one ventricle; a few of them have imperfect lungs, but the greater number breathe through gills. They have all the power of remaining a long time in a state of rest, and their movements are either slow or violently laborious. Some of them appear incapable of locomotion. They produce their young from eggs, but some lay their eggs on a part of their own body, where the young are hatched. The following are Cuvier’s six classes:—
1. Cephalopoda, or Head-footed Mollusca. These animals are furnished with long fleshy arms or feet, proceeding from the head, which is not distinct from the body, and on which they crawl. There is only one order, which includes the cuttle-fish, nautilus, and belemnites.
2. Pteropoda, or Wing-footed Mollusca. These animals have two membranous feet or arms, like wings, proceeding from the neck. There is only one order, which contains six genera, the best known of which is the Hyalæa, the shell of which is commonly called Venus’s chariot.
3. Gasteropoda, or Body-footed Mollusca. All these animals crawl with the flat part of the body, which acts as a kind of sucker. There are nine orders in Cuvier’s system. The common snail will give an idea of the habits of the class.
4. Acephala, or Headless Mollusca. These animals have no apparent head, and breathe by means of branchiæ, which are generally ribbon-shaped. Most of them are enclosed in a bivalve shell, but some are naked; the former are the Testacea of Cuvier, and the Conchifera of Lamarck; the latter are the Tunicata of Lamarck. They form two orders.
5. Brachiopoda, or Arm-footed Mollusca. These animals also have a bivalve shell; but they have no true branchiæ, and their respiration is effected by the agency of the mantle. They have two spiral arms.
6. Cirrhopoda, or Curled-footed Mollusca. These are generally attached, and enclosed in a shell of several pieces; they are furnished with a mouth, armed with jaws, and with several pairs of jointed and fringed organs, called cirri, by the protrusion and retraction of which they capture their prey. Examples of this class are the Barnacles and Acorn shells. These animals have long ceased to be regarded as Mollusca, the investigations of modern naturalists having proved them to be true articulated animals most nearly related to the Crustacea.
THE ARTICULATED ANIMALS
Have no back-bone. The covering of the body is sometimes hard and sometimes soft, but it is always divided into segments by a number of transverse incisions. The limbs, when the body is provided with any, are jointed; and they can be separated from the body without any serious injury being sustained by the animal, new limbs being shortly after formed to replace them. The senses of tasting and seeing are more perfect than those of the Mollusca, though that of feeling seems much less acute. In other respects the four classes differ considerably from each other.
[The Entozoa, or Intestinal Worms, placed by Cuvier and others among the Radiata, are now arranged amongst the lowest forms of articulated animals, as are also those animalcules known as Rotifera.]
I. The Annelida, or Red-blooded Worms, have no heart, properly so called, but have sometimes one or more fleshy ventricles. They breathe through branchiæ. Their bodies are soft, and more or less elongated, being divided into numerous rings or segments. The head, which is at one extremity of the body, can scarcely be distinguished from the tail, except by having a mouth. These animals have no feet, properly so called, but they are furnished with little fleshy projections, bearing tufts of hairs or bristles, which enable them to move. They are generally of carnivorous habits. They lay eggs, but the young are frequently hatched before exclusion, and hence these creatures are said to be ovoviviparous. Their study is called Helminthology. As examples of the three orders of this class may be mentioned the serpulæ or worm-like animals, often found on shells, the common earthworm, and the leech family.
II. The Crustacea comprise the shell-fish commonly called crabs, lobsters, shrimps, and prawns. They have a distinct head, furnished with antennæ, eyes, and mouth; and their bodies are covered with a crust or shell, divided into segments by transverse incisions, the segments being united by a strong membrane. Once a year the larger species of these animals moult, throwing off their old crust or shell, and forming a new one, the animal remaining in a naked and greatly weakened state during the intermediate time. Many of the Crustacea swim with great ease, but on land their motions are generally cramped and awkward; and they are confined to crawling, or leaping by means of the tail. When a limb is injured they possess the extraordinary power of throwing it off, and forming a new one. The Crustacea lay eggs, and the young of some of the species undergo a transformation before they attain their full size. The Crustacea were divided into two sections and seven orders by Latreille, which are as follow:—
Section I. Malacostraca
Shell solid, legs ten or fourteen, foot-jaws six or ten, mandibles two, maxillæ four; mouth with a labrum.
Sub-section I. Podophthalma, eyes on foot-stalks.
Order 1. Decapoda, legs ten.
Sub-order 1. Brachyura, the crabs.
Sub-order 2. Macroura, the lobsters.
Order 2. Stomapoda, legs more than ten.
Sub-section II. Edriophthalma, eyes not on foot-stalks.
Order 3. Amphipoda, body compressed; mandibles palpigerous.
Order 4. Læmodipoda, abdomen rudimental, with only the rudiments of one or two pairs of appendages.
Order 5. Isopoda, body depressed; abdominal appendages flat; mandibles not palpigerous.
Section II. Entomostraca
Shell not solid; legs variable in number; mouth variable.
Order 6. Branchiopoda. Integuments horny, branchiæ feathery, forming part of the feet.
It is to this division of the Crustacea that the Cirrhopoda are now referred.
Order 7. Pæcilopoda, mouth suctorial.
Sub-order 1. Xiphosura, or king-crabs.
Sub-order 2. Siphonostoma, or fish parasites.
III. The Arachnida are defined by Lamarck to be oviparous animals, provided with six or more articulated legs, not subject to metamorphosis, and never acquiring any new kinds of organs. It is now known, however, that some mites undergo a sort of metamorphosis, having only six legs when first hatched, and passing through a quiet pupa stage before acquiring their perfect form. Their respiration is either by means of air-sacks, which serve for lungs, or of a kind of tube with circular openings for the admission of air. There is a rudimentary heart and circulation in most of the species. There are two orders; those with lungs, and those without.
Order I. Pulmonariæ. The Arachnides comprised in this division have air-sacks, which serve for lungs, a heart with distinct vessels, and from six to eight simple eyes. There are two distinct families: viz. Araneides, comprising all the spiders and spinners; and Pedipalpi, comprising the tarantula and scorpions.
Order II. Tracheariæ. These Arachnides are distinguished by their respiratory organs, which consist of radiated or branched tracheæ, receiving air by two circular openings. Their eyes vary from two to four. The principal animals belonging to this division are the long-legged spiders (Phalangium), and the mites (Acarus), including the gardener’s pest, the little red spider (Acarus telarius), the cheese mite (Acarus Siro), and the harvest bug (Acarus or Leptus autumnalis).
IV. The Insecta form the fourth and last class of articulated animals, and they derive their name from the Latin word insectum, which signifies “cut into,” in allusion to the distinct divisions of head, thorax, and abdomen in the true insects: and in contradistinction to the Annelides, the bodies of which present no such divisions. The true insects are defined as animals without vertebræ, possessing six feet, with a distinct head furnished with antennæ, and breathing through stigmatic openings, which lead to interior tracheæ. The Myriapoda have, however, more feet. The following are the twelve orders into which this class is divided.
Section I. Insects Undergoing Metamorphosis
1. Coleoptera (from two Greek words signifying sheathed wings). These are the beetles, which are all furnished with membranous wings, with which they fly, and which are protected by horny upper wings, or wing-cases, called elytra. They are all masticators, and are all provided with mandibles or projecting jaws, and maxillæ.
2. Orthoptera, or straight-winged insects. This order comprises the crickets, grasshoppers, locusts, and similar insects. They have their upper wings of the consistence of parchment, and have mandibles and maxillæ.
3. Hemiptera, or half-winged insects, have frequently half the upper wing membranous, like the under ones, while the other half is leathery. To this division belong the bugs, the water-scorpions, the cicadæ or froghoppers, and the aphides. These insects have neither mandibles nor maxillæ, but in their place have a sheath and sucker.
4. Neuroptera, or nerved-winged insects, such as the dragon-flies, have both pairs of wings membranous, naked, and finely reticulated. The mouth is adapted for mastication, and furnished with mandibles and maxillæ.
5. Hymenoptera, membranous winged insects, such as bees, wasps, ichneumon flies, &c. All the four wings are membranous, but they have fewer nervures, and are not reticulated like those of the preceding order. The mouth is furnished with mandibles and maxillæ, and the abdomen is terminated either by an ovipositor or a sting.
6. Lepidoptera, or scaly-winged insects. These are the butterflies and moths, which are characterised by the farinaceous or scaly aspect of their wings, and the tubular or thread-like extension of the parts of the mouth.
7. Strepsiptera or Rhipiptera, with twisted wings. These creatures resemble the ichneumon, in laying their eggs in the bodies of other insects, though they generally attack wasps and bees. The principal genera are Xenos and Stylops. They are generally considered to be closely allied to the Beetles.
8. Diptera, or two-winged insects, including the flies. The mouth is furnished with a proboscis, and there are two small wings called halteres placed behind the true wings, which act as balancers.
9. Suctoria, or sucking insects, such as the flea, which have no wings, but are furnished with an apparatus for sucking blood.
Section II. Insects Not Undergoing Metamorphosis
10. Thysanoura, or spring-tail insects. These creatures are of small size, and without wings; they are found in crevices of woodwork, or under stones. The principal genera are Lepisma and Podura.
11. Parasita, or parasitical insects, such as the louse. They are also without wings.
12. Myriapoda. This order is made a separate class by many naturalists, as the creatures contained in it are distinguished from the true insects by the great number of their feet; by the want of distinct divisions into thorax and abdomen; and by the great number of segments into which the body is divided. The principal insects in this order are included in the Linnæan genera Julus and Scolopendra, commonly called centipedes.
The term larva is applied to the young of all insects, included in the first nine orders, when first hatched. The different kinds have, however, other names; that is to say, the larva of a butterfly, or moth, is called a caterpillar; that of a beetle, a grub; and that of a fly, a maggot. The larva changes its skin several times, and at last goes into the pupa state, when it is called a chrysalis, an aurelia, or a nymph. Sometimes the pupa is wrapped up in a loose outer covering called a cocoon. From the pupa in time bursts forth the imago, or perfect insect. The Apterous, or wingless true insects, and the Myriapoda, which are also without wings, do not undergo any metamorphosis.