The Pelican. face, while the pelicans are restricted to the warmer latitudes. The Frigate-birds are nearly allied to the Cormorants, but differ from them in the excessive spread of wing (which renders them the most powerful flyers in this order-perhaps not being surpassed by any other bird), and in the form of the tail and bill. They feed upon fish, especially flying-fish, both. darting at it themselves, when near the surface, and obtaining it from other birds, whom they compel to drop their prey. The Gannets are allied to the frigate-birds; but the wings are less extended, and the powers of flight inferior. Some species are termed Loobies, from the stupidity they exhibit when attacked. A species about the size of a goose is very common in the British seas, and breeds especially on the Bass Rock, in the Firth of Forth. The Gannets take their prey by hovering in the air at some little distance above the surface, and then dropping down upon any fish that they may see rising within their reach. The air-cells are very largely developed, especially under the skin of the breast, which is almost completely separated by them from the muscles beneath; and it is probable that they may serve as an elastic cushion, to break the force with which the body of the bird would otherwise impinge on the water. 4. The COLYMBIDE, or Divers, may perhaps be regarded as intermediate in structure between the Duck tribe and the next family. They are all marine birds, The Little Auk. 5. The ALCIDE, or Auk tribe, exhibit the most remarkable adaptation of the structure of the bird to an aquatic life, with which the entire order presents us. This is best seen in the Penguins, whose wings are very small, and covered with mere vestiges of feathers, which resemble scales; so that they serve as admirable fins or paddles, but are totally useless for flight. The feet are placed very far back, so that when upon land the bird stands nearly erect. Having no power of flight, and not being able to run, the penguin may be overtaken with ease upon land; but once in the water, it distances its pursuers, swimming with the ease and rapidity of a fish, and springing several feet over any obstacle that may impede its course. CLASS III-REPTILES. The class of Reptiles, which is the next to oe considered, presents us with more diversity of form among its separate orders than any other division of the vertebrated sub-kingdom. Scarcely any animals are more unlike in external aspect than tortoises and serpents; yet we shall find that these extreme forms are connected with each other by a gradual series, and the internal differences are not so great as to prevent their association into one class, distinguished by characters which are common to all. These characters are their low power of maintaining heat, or cold-bloodedness, arising from the imperfect aeration of their blood, of which only a portion is sent to the lungs at each impulse of the heart (see article PHYSIOLOGY); their oviparous reproduction; the respiration of air exclusively during the whole period of life, no metamorphosis taking place in this class; and the protection of the skin by hard scales or plates. By the first two they are distinguished from Mammalia and Birds, and by the others from Fishes and Amphibia. The deficiency in the oxygenation of the blood, combined with the slowness and feebleness of the circulalation, is connected with general inactivity of the nutritive functions, as well as with obtuseness of sensation and sluggishness of locomotion. It is a curious result of the feeble exercise of these functions, that, as in Amphibia, they may be suspended for a considerable time without apparent injury to the animal; and that parts completeness of their shelly covering, and by the pecuseparated from the body retain for a long period much liar modification of the feet for swimming. The ribs, of that low degree of vitality which they usually exhibit by the union of which the carapace is formed, are sepain connection with it. Although at present Reptiles ap-rate from one another around its margin, and the pieces pear to perform a comparatively insignificant part in the which compose the plastron do not form a continuous economy of nature, especially in temperate climates, plate, but leave great intervals, which are occupied only where their numbers are few and their powers feeble, by cartilage. All the feet are much elongated, particu we learn from the records of geology, that there was a larly the anterior pair, and are flattened so as to serve period in the earth's history, long antecedent to the cre- for oars or paddles. The toes are seldom at all sepaation of Birds and Mammalia, when gigantic animals of rated, the whole foot being enveloped in the same skin, this class not only constituted the chief tenants of the earth, closely set with hard plates. They live almost entirely but extended their dominion over the waters of the sea. at sea, feeding chiefly upon marine plants, and 'they only The three well-known forms, Tortoises, Lizards, and come to the shore to deposit their eggs. The œsophaSerpents, may be taken as the types of three orders into gus (gullet) of these animals is lined with long cartilawhich this class may be subdivided, namely, the CHELO- ginous processes, all directed towards the stomach; NIA, SAURIA, and OPHIDIA. But, in order to embrace these seem to have for their object the prevention of the some of the fossil species, which present us with other return of the food, which is swallowed together with a types of structure, it is desirable to create another order- large quantity of water; and, when the stomach afterthe ENALIOSAURIA-intermediate between the Turtles wards ejects the superfluous fluid, these spikes prevent and Crocodiles; and this last tribe, though possessing the food from being regurgitated with it. the general form of lizards, so far differs from them in the covering of the body (which consists of large plates instead of scales) as well as in some points of internal organization, that a distinct order, LORICATA, has been formed for it. These five orders may then stand thus:1. CHELONIA, including the Turtles, Tortoises, &c.; 2. ENALIOSAURIA, to which the Plesiosaurus, Ichthyosaurus, and other fossil remains belong; 3. LORICATA, comprehending the Crocodiles, Alligators, &c.; 4. SAURIA, including the remainder of the Lizard tribes; 5. OPHIDIA, the Serpents. Order I.-Chelonia. Green Turtle. The most important species of this group are the cha lone midas, or green turtle, so much valued as an artice of food; the chelone imbricata, or hawk's-billed turtle, the plates upon whose carapace furnish our tortoise-shell; and the sphargis, or leathery turtle, which has the shell covered by a thick leather-like skin. They are all chiefly found in warm latitudes. The order Chelonia differs the most of any of these from the general form of the group. The shell in which the body is enclosed, and into which, in some species, the head, legs, and tail, can be completely withdrawn, would seem a perfectly new organ, to which nothing corresponding exists among vertebrated animals. And the fin-like extremities of the aquatic species remind us The EMYDE, Fresh-water Turtles, or Mud Tortoises, more of fish than of other reptiles. The shell, however, are intermediate in form between the family just described is composed of the usual bones of the skeleton, modi- and the Land-tortoises. The character by which they fied only in their form. The upper piece, termed the may be most constantly separated from the marine Turcarapace, is usually more or less arched, and is com- tles, is the distinctness of their toes, which are termiposed of a bony expansion of the ribs, which are conso-nated by claws; but a web still exists between the toes, lidated into a firm structure, adhering to each other along their edges, and are covered with horny plates, secreted from the skin like hair or nails. The lower plate, or plastron, is formed by a peculiar development of the sternum or breastbone, which, instead of being prolonged forwards into a keel, to give attachment to large muscles, as in birds, is extended laterally for the protection of the subjacent parts. Most of the Chelonia are deficient in weapons of of fence, being destitute of teeth, claws, or other sharp instruments. The jaws are covered with a horny substance, resembling that of the bills of birds; but their surfaces are usually rounded, so as to be more adapted to bruise than to bite. The shell, however, serves as a most effectual means of passive resistance. In the land species it is usually high-arched, and firmly united, so as to bear a very great weight without injury; and the feebleness of the power of motion in these animals is thus compensated. But in the aquatic species it is generally more flattened, so as to oppose less resistance to the water. Some of these have the power of swimming with considerable rapidity, and are altogether more active in their habits than the rest of the order. In these, the shell affords a much less complete protection to the body, and its parts are more loosely united, so that it possesses some degree of flexibility. Among the families into which the Chelonia are subdivided, it will be convenient to notice first the CHELONIDE, or Turtles. These are distinguished by the in which assists them in swimming, and also prevents the feet from sinking into mud. Rivers, ponds, and running streams, are the haunts of these animals, of which one species is common in the south and east of Europe, and is fattened for food in Germany and Russia, where it is considered a delicacy. The food of the Emydæ consists of mollusca, aquatic insects, small fish, carrion and vegetables. The species at present existing seldom attain any great size, their shells varying from one and a half inch to a foot in length; many of the fossil species are much larger. In several of the Emyde the carapace and the plastron are but loosely united; and the pieces of the latter are movable upon one another. This is the case in the Terrapins, or Box-tortoises, which are able to draw the head and limbs completely into the shell, and to close the latter by folding the anterior, and in some instances the posterior, division of the plastron against the carapace. The family of TESTUDINIDE, or Land-tortoises is distinguished by the highly arched carapace, and, still more, by the short clubby feet, of the animals composing it. Their armour is harder and thicker in proportion to their size, and also more firmly united together, than that of the aquatic species. The neck and legs are short, and are capable of being drawn entirely within the shell; so that the whole structure of the animal is adapted for passive resistance. The feet, shaped very much like those of the elephant, are adapted for walking on firm ground only, as the surface they present is very small. They are subdivided into toes, of which there are five on the fore feet and four on the hind; and these are furnished with short conical claws, well adapted for digging. These animals are of the most inoffensive character possible. They feed only upon roots and vegetables, and upon the worms and slugs that infest these; during the summer they live in woods or among herbage; and they pass the winter, in cold climates, beneath the earth, where they burrow and sleep. They are generally dispersed in all the warm and temperate latitudes; but they do not naturally extend to Great Britain, although individuals that have been introduced have lived to a great age in this country. The commonest species is the Testudo Grær, which is an inhabitant of most of the conunent of Europe, as well as of many parts of Asia and Africa; it especially abounds near the shores of the Mediterranean. It seldom attains above a foot in length, or weighs more than three pounds. The flesh forms an article of food in Greece. In the East Indies are found species which attain to a much greater size. An individual in the possession of the Zoological Society of London, measures 4 feet 4 inches along the curve of the back, the breadth of the shell being 2 feet l'inch, and the weight of the whole animal 285 lbs. Order II-Enaliosauria. The order Enaliosauria has been founded upon two extraordinary fossil genera, the Icthyosaurus and the Plesiosaurus. Of these little else than the bones has been preserved to us; and it is therefore impossible to speak with certainty in regard to many parts of their organization. The character by which they are especially connected with the Chelonia is the flattening of the extremities into fin-like paddles, resembling those of turtles. They must have been, therefore, marine animals, endowed with scarcely any power of movement on land; but, although in many points analogous to fish, it is nearly certain that they breathed air like reptiles in general, and that they must have occasionally come to the surface to respire. Moreover, from the remains found in proximity with them, it may be surmised with probability that they fed upon marine animals alone, especially upon the various forms of Cephalopoda, which were particularly abundant at the epoch of their existence. The general form of the Icthyosaurus (or fish-lizard) appears to have been not unlike that of a crocodile, with the substitution of fins for feet. The head is lengthened into a narrow pointed muzzle, and the jaws armed with sharp and formidable teeth; and it had eyes of enormous size, which must have given it an extraordinary aspect, and probably enabled it to see by night. The skeleton of the commonest species (I. tenuirostris) usually measures 3 feet in length; but portions of another kind have been found, which must have belonged to animals of above 20 feet. It is probable that the skin was destitute of scales, like that of the Amphibia; and, from recent inquiries, it appears that it possessed a sort of cartilaginous fin upon its back, like that of many Cetacea. This animal may thus be considered as presenting a very remarkable combination of the characters of other classes. Its remains, which are found in the lias and oolitic formations, are more abundant in England than in any other country in Europe. The Plesiosaurus was distinguished by the extraordinary length of its neck, which, in the commonest species (P. dolichodeirus), occupies nearly half the entire length. The head is very small in proportion, and the tail is short, stout, and pointed. The cervical vertebræ exceed in number those of any other animal known; and in their conformation, have a good deal of resemblance to those of the body of a snake. It is the conjecture of Mr. Conybeare, by whom the first scientific investigation of the characters of this strange creature was made, that thed air and had frequent need of respiration, it generally swam upon or near the surface of the water, arching back its long neck, like the swan, and plunging it downwards at the fishes that passed within its reach. The greater length of its extremities would enable it to move on land with somewhat less difficulty than the Icthyosaurus; and it might have very probably lurked in shallow water along the coast, where it could find shelter from its enemies, and a place of ambush from which to dart out its long neck upon its own prey Its length seems generally to have been about ten feet. The order Loricata, including the Crocodiles, Alligators, and Gavials, may be regarded as in many respects intermediate between the fresh-water Tortoises and the true Lizards. The body is enclosed in a sort of platearmour, of which the separate portions are closely fitted together, and are capable of great resistance. Another character by which they are distinguished is the flattening of the foot, which is furnished with a kind of web between the toes, like that of the Emydæ : in the true lizards no such provision for aquatic habits is found. This order includes the most bulky reptiles at present known to exist. Some of them attain the length of thirty feet, and a circumference of seven or eight; so that, with the exception of the elephant, the rhinoceros, and the hippopotamus, there is no terrestrial animal exceeding these dimensions. Although capable of moving on land, however, the greater number of them prefer the water, and show their chief activity in it. Besides the expansion of the foot, they are adapted for swimming by the lateral compression of the tail, which thus acts as a large and powerful fin. The crocodiles and their allies are all inhabitants of the rivers and fresh waters of warm climates; and they are all purely carnivorous. They destroy their prey by holding it beneath the surface of the water until it is drowned; the position of their nostrils, and the arrange ment of the air-passages, being such that they are themselves enabled to breathe during the process. They cannot swallow under water, however, and their habit is to hide their prey in holes on the bank, until it has become putrid, and then to devour it at their leisure. The conformation of the neck is such, that the head cannot be moved very far from side to side, though its play in the vertical direction is not limited. The animal finds it difficult, therefore, to turn itself round upon land; and thus a sure means of escape presents itself in those rare cases in which it leaves the water in pursuit of human prey. The tail, however, is very flexible from side to side, and is of great importance in propulsion. It also serves as an important weapon, for it is armed, like the back, with very strong upright plates, which form sharp ridges or crests in their centre; with this weapon the crocodiles can inflict terrific wounds upon their enemies. This group is entirely confined to the countries bordering on the equator. The animals which compose it may be considered in three subdivi sions-the Crocodiles, chiefly inhabiting the Nile and other African rivers; the Gavials, found in the Ganges and other Asiatic rivers; and the Caymans or Alligators, confined to the New World. The characteristic differences of these three divisions are best marked in the form of the head. The Gavials Alligator. have the muzzle exceedingly prolonged and narrow, somewhat resembling in form the beak of the spoonbill. In the true Crocodiles it gradually widens from the point towards the eyes; and in the Caymans the snout is much more rounded, and the head is broader in proportion to its length. These last appear less adapted to aquatic habits than the Crocodiles and Gavials, for the feet are not webbed to nearly the same extent as in the latter, and the ridge which increases the surface of their hind legs is wanting in the Alligators. With these exceptions, however, the general conformation of all, as well as their mode of life, is very similar. Order IV.-Sauria. The order Sauria comprehends all the animals commonly known as Lizards. They are intermediate between the Loricata and Serpents, for they have a lengthened body, terminating in a tail, like the former; but this. instead of being enclosed in large shields or plates, is covered with small scales, as in the latter. Moreover, they have usually four legs; but in some species one pair disappears, and in others they are all concealed heneath the skin, so that the body presents a snake-like aspect. In this group are found some of the most active, and certainly the most beautiful, of the Reptile class. Many of them are tinctured with the most brilliant colours, and as they are called into the greatest activity in the bright sunshine, nothing can surpass the splendour of their ever-changing hues. These colours bear an interesting relation to the habits of the animal, having a general resemblance to that of the places they frequent; thus tree-lizards are almost always of bright colours, in which green predominates; ground-lizards, brown, more or less speckled; and those which live in stony places are of a grayish hue. The greater part of the Sauria are carnivorous, feeding upon other animals of inferior size and strength to themselves, and almost always preferring living prey. Many of them pursue nothing but insects; others lie in wait for small birds. The Iguanas, however, feed almost wholly upon vegetables. Many of them are possessed of very great agility upon land; some of them can ascend perpendicular walls, and even run along the ceiling with their backs downwards; none of them are inhabitants of the water, though a few occasionally resort to it. The activity of the smaller insectivorous lizards, when in pursuit of their food, is exceedingly curious and interesting. They watch with all the caution of a cat, and dart upon their prey with the quickness of lightning. Their movements are effected chiefly by means of their feet, and in the higher tribes exclusively so; but in those species in which the legs are short and the feet very small in proportion to the length of the body, progression is greatly assisted by the lateral motion of the trunk, which works its way along somewhat in the manner of that of the serpents. The order Sauria may be subdivided intc five families VOL. II.-52 -1. The LACERTINIDE, characterized by the small head and thick neck, but particularly by the very long slender forked tongues of the animals composing it. This group includes the common lizards of this country, and most of the Saurians whose habits are peculiarly active. 2. The IGUANIDE, having the same general form, but short thick tongues. This group includes some of the largest of the Sauria, both recent and fossil. 3. The GECKOTIDE, which are all nocturnal animals. These have not the attenuated form of the previous families, but are flattened, especially on the head. Their legs are short, and their movements comparatively tardy. Their colour is usually very sombre; and they are reputed, but without foundation, to be venomous. 4. The CHAMELEONIDE, whose tongue is of immense length, but obtuse at its point. The feet and tail are both peculiarly adapted for climbing; the former having two of the toes opposable to the rest, and the latter being round and prehensile. Their movements are very slow, except when the tongue is darted out to secure its insect prey. 5. The SCINCOIDE, or Serpent-lizards, which are recognised by the shortness of the feet, the non-extensibility of the tongue, and the equality of the tile-like scales which cover the whole body and tail. 1. The LACERTINIDE are the most agile, most innocent, and most beautiful of the Saurians. Though they share, in common with the others, the dislike in which the animals of the class of reptiles are held by most persons, they never injure man, and are in some cases of considerable service to him. The larger ones live on the ground, usually preferring the shelter of underwood or of stones, and some frequenting marshy situations; whilst the smaller kinds resort to trees in search of their insect food, and, in the liveliness of their colours and the rapidity of their motions, bear no inconsiderable resemblance to birds. Two small species inhabit this country the lacerta agilis, or sand-lizard, a beautiful little animal, which is sometimes of a brown and sometimes of a greenish hue; it is found on sandy heaths, and occasionally seen basking on the sunny sides of green banks. A more common one, however, is the lacerta vivipara, which inhabits most districts of England, and even extends into Scotland; it is also one of the few reptiles found in Ireland. It frequents heaths and banks, and may be seen on the watch for its insect prey, during the warm parts of the day, from the early spring until summer has far advanced. Its name is derived from a peculiarity which it shares with the viper-its eggs are retained and hatched within the body, so that the young are produced alive. Some gigantic fossil bones have been discovered, which seem to be the remains of enormous Saurians, allied in structure to the Lacertidae of the present time. From the proportional length of the head of one of these, which is nearly the sole part preserved, this lizard must have been at least seventy feet from head to tail. 2. The family of IGUANIDE approaches pretty closely to the true lizards in many of its general characters; but it contains several most extraordinary forms, widely differing from each other. The true Iguanas are confined to America; but some genera of this order are found over the greater part of the tropical zone. Among these may be noticed the genus Draco, the animals included in which are distinguished at the first glance from all other saurians, by the possession of a pair of wing-like appendages to the sides of the body. These are formed by extensions of the skin, supported by the false ribs, which are greatly prolonged. They can be folded up or extended at the will of the animal, but they cannot be made to strike the air and to elevate the animal like a bird or at. They serve rather as a kind of parachute, on which this little dragon, not many inches long, flutters from branch to branch in search of its insect prey; and also as a support to it when shooting, like the flying-squirrel, from tree to tree. These animals, the only living representatives of the fabulous dragons of the olden time, are found in the woods of tropical Africa and Asia, especially in the Indian archipelago. This is perhaps the proper place to notice the very extraordinary fossil, to which the name pterodactylus has been given. In its general character it was certainly a lizard; but it seems to have been adapted to raise itself and fly in the air, like a bat or bird. The membrane of the wing was not extended, however, over the whole bony apparatus of the limb, but only one finger, which was enormously developed to support it. It is ranked by Cuvier among the most extraordinary of all the extinct animals that had come under his consideration; and the one which, if we saw them all restored to life, would appear most strange, and most unlike to any thing that exists in the present world. In the form of its head and the length of its neck, it resembled birds, but it had the bones and teeth of a lizard; its wings approached those of bats in form and proportion; and its body and tail resembled those of ordinary Mammalia. In general external form, the pterodactyles probably most resembled a vampire bat; but in most of the species, the snout was elongated like that of a crocodile, and armed with conical teeth. Their eyes were of enormous size, apparently enabling them to fly by night. From their wings projected fingers, terminated by long hooks, like the curved claw on the thumb of the bat. These must have formed powerful members, with which the animals were enabled to climb, or creep, or suspend themselves from trees. With regard to their food, it has been conjectured that they preyed upon insects; and the number of fossil remains of insects in the strata in which they are found, proves that such a source of aliment was within their reach. The head and teeth of two species, however, are so much larger than would be required for the capture of insects, that they may have possibly fed on fishes (as there were at that epoch few or no small land animals), darting upon them from the air after the manner of many sea-birds. From this account of the pterodactylus, it is evident that it is a most remarkable connecting link between the classes of birds and reptiles. That it is to be associated with the latter can scarcely be questioned; but if, as has been recently stated, the covering of the skin was more analogous to hairs or feathers than to scales, its affinity to birds must have been extremely strong. Iguana. The true Iguanas are confined to the New World, and frequently attain considerable size. They have a kind of spine or crest along the back, and a hanging pouch under the throat, which seems analogous to the dewlap of oxen; this pouch can be inflated, but under what circumstances is not exactly known. They have also in some degree that power of changing the hue of the skin, which is so remarkable in the chameleon. They are very agile, the legs being long in proportion to the body, and their food is almost exclusively vegetable. Some of them attain the length of five or six feet, of which the tail constitutes a large proportion. Their flesh is much esteemed as food; and, in the countries where they abound, they are sought for with this object. They are extremely tenacious of life. When attacked, they assume a formidable, though not a dangerous, aspect. They open heir mouths, vibrate their tongues with rapid motion, inflate their throats, and erect their crests, while their eyes glance with great brilliancy. All this, how. ever, is a demonstration for defence and not for attack. They are never known to combat with any animals bu those of very small size. Some gigantic fossil remains, allied in conformation to the Iguana, indicate the former existence of animals af similar character, which attained enormous bulk. The chief of these was the iguanodon, of whose bones fragments have been found in Tilgate Forest. The teeth are so precisely similar to those of the iguana in the principles of their construction, as to leave no doubt of the near connection of this gigantic saurian, which must have probably attained a length of at least seventy feet, with the herbivorous lizards of our own time. The examination of these teeth discloses some re mechanical contrivances, adapting them to the function of cropping tough vegetable food, such as that afforded by the plants found imbedded with it. The third family, the GECKOTIDE, consists of a large number of animals bearing a strong resemblance to each other in general characters. They are all nocturnal, and pass the day in obscure places; their eyes are large, and their pupil contracts under the influence of light, like that of cats, into a very small aperture. Their flattened form and broad head give to them a very striking and peculiarly disagreeable appearance, which is aided by their sombre and somewhat toad-like hue; hence, although timid and harmless, they are always regarded by the vulgar as having a venomous character, but without the least foundation in truth. Most of them possess claws at the extremities of the toes, and these are capable of being retracted like those of the Feline. They appear more useful to their possessor in climbing, however, than in securing their prey, which consists principally of insects. The Geckos are found in most warm countries in both hemispheres. They frequent buildings; and some species have a peculiar organization of the feet, by which they can climb smooth perpendicular walls, or even run beneath ceilings. They are often useful in clearing houses of musquitoes and spiders; but it is said that articles of food over which they have passed acquire poisonous properties, in consequence of an acrid exudation from the feet. It is difficult to know how much credit to give to such statements; equally positive ones, which are entirely destitute of foundation in fact, being circulated in this country in regard to the toad. The CHAMELEONIDE, or Chameleon tribe, are few in number; but they present so many anomalies of organization, that it is necessary to separate them from all the other saurians, and to rank them as a distinct family. They are characterized, in the first place, by the structure of the feet, which are adapted for climbing, like those of the scansorial birds (such as the parrot), having two of the toes opposed to the other three. The tongue also affords a remarkable character; it is fleshy, and capable of enormous elongation; the extremity is thickened or club-shaped, and is furnished with a viscous secretion at its extremity. It is by this organ that the |