early tertiary formations (the Eocene period of Lyell) down to the oolite and lias, in both of which strata they occur; and it is worthy of observation that the deviations from the existing genera and species increase in degree, as the beds containing those extinct species indicate periods more remote from the present time, as Professor Owen has pointed out.

Dr. Buckland, in a few eloquent words, has summed up the appointed task of these ancient agents in the police of nature. After observing that their occurrence in a fossil state is of high importance, inasmuch as it shows that whilst many forms of vertebrated animals have one after another been created and become extinct, during the successive geological changes of the surface of our globe, there are others which have survived all these changes and revolutions, and still retain the leading features under which they first appeared in our planet, he thus proceeds:

If we look to the state of the earth, and the character of its population at the time when crocodilian forms were first added to the number of its inhabitants, we find that the highest class of living beings were reptiles, and that the only other vertebrated animals which then existed were fishes; the carnivorous reptiles at this early period must therefore have fed chiefly upon them, and if, in the existing family of crocodiles, there be any that are in a peculiar degree piscivorous, their form is that we should expect to find in those most ancient fossil genera, whose chief supply of food must have been derived from fishes. In the living sub-genera of the crocodilian family, we see the elongated and slender beak of the gavial of the Ganges, constructed to feed on fishes whilst the shorter and stronger snout of the broad-nosed crocodiles and alligators give them the power of seizing and devouring quadrupeds that come to the banks of rivers in hot countries to drink. As there were scarcely any mammalia during the secondary periods, whilst the waters were abundantly stored with fishes, we might à priori expect that if any crocodilian forms had then existed, they would most nearly have resembled the modern gavial. And we have hitherto found only three genera which have elongated beaks, in formations anterior to and including the chalk; whilst true crocodiles, with a short and broad snout like that of the cayman and the alligator, appear for the first time in strata of the tertiary periods, in which the remains of mammalia. abound. During these grand periods of lacustrine mammalia, in which but few of the present genera of terrestrial carnivora had been called into existence, the important office of controlling the excessive increase of the aquatic herbivora appears to have been consigned to the crocodiles, whose habits fitted them in a peculiar degree for such a service. Thus the past history of the crocodilian tribe presents another example of the well-regulated work

ings of a consistent plan in the economy of animated nature, under which each individual, whilst following its own instinct, and pursuing its own good, is instrumental in promoting the general welfare of the whole family of its contemporaries."*

Our attention is next arrested by the ancient terrestrial dragons,

THE DINOSAURIANS,†

as Professor Owen has aptly termed them, and although he has, upon the most satisfactory data, somewhat reduced the enormous dimensions originally assigned to them, "fearfully-great lizards" must they have been.

This tribe of gigantic crocodile-lizards of the dry land, as Professor Owen designates them with his usual accuracy, excepting that we may be permitted to express our doubts as to the land being very dry, are, he observes, as clearly distinguished from the modern terrestrial and amphibious saurians, as the opposite modifications for an aquatic life characterize the extinct Enaliosaurians or marine-lizards. To Professor Buckland and Dr. Mantell are those interested on the subject—and their number is, we are happy to say, no longer small-principally indebted for a knowledge of these wonderful and long-buried forms which once had dominion where Queen Victoria now reigns.

One of the most distinguishing characteristics of these great land-lizards is the possession of marrow-bones. The great bones of the extremities of the Enaliosaurians and ancient crocodilians were solid throughout, and the comparative weight, so far from being inconvenient in the medium through which they generally had to make their way, performed the office of ballast to steady them in and on the water, and prevent them, when on the surface, from exposing too much of their bodies, and being what the sailors call crank.

But in the enormous and dragon-like forms now under consideration, those oviparous quadrupeds, in short, whose progression was to be performed on the land, and most probably in sandy or miry places and sloughs, a combination of lightness with strength was required, and the narrow-filled cylinder made the appropriate machinery complete.

Here is Professor Owen's general definition of his Dinosaurians:

"This group, which includes at least three well-established genera of Saurians, is characterized by a large sacrum composed

of five anchylosed vertebræ, of unusual construction, by the height and breadth and outward sculpturing of the neural arch of the dorsal vertebræ, by the twofold articulation of the ribs to the vertebræ,—viz., at the anterior part of the spine by a head and tubercle, and along the rest of the trunk by a tubercle attached to the transverse process only, by broad and sometimes complicated coracoids and long and slender clavicles, whereby crocodilian characters of the vertebral column are combined with a lacertian type of the pectoral arch; the dental organs also exhibit the same transitional or annectent characters in a greater or less degree. The bones of the extremities are of large proportional size for saurians; they are provided with large medullary cavities, and with well-developed and unusual processes, and are terminated by metacarpal, metatarsal, and phalangeal bones, which, with the exception of the ungual phalanges, more or less resemble those of the heavy pachydermal mammals, and attest, with the hollow ⚫ long-bones, the terrestrial habits of the species."*

The most remarkable of these Dinosaurians hitherto discovered are the Iguanodon, the Megalosaurus, and the Hylæosaurus. We will commence with the

IGUANODON.

The habits of the existing members of the family of crocodiles are so well ascertained and familiarly known, that it would have been needless to go into details on that head; but the manners of the Iguanas or Guanas which are now living, and come nearest to the great extinct Iguanodon, are not so generally understood. A few words, therefore, explanatory of their form and mode of life, may not be uninteresting previous to a description of the old

saurian.

The modern Guanas are lizards with iong scaly bodies and tails, furnished with a depending, deep, thin, gular pouch, also covered with scales, and serrated on the anterior portion of the edge near the chin. The head is somewhat pyramidal. The neck is a little compressed, and there are cuticular folds on its sides and on the trunk, the upper part of which is convex and rounded, and the under part flattened. The tail is very long and slender, slightly compressed on its sides. The rather long limbs are terminated by five toes with serrated edges and sharp claws, the three middle toes longer than the outside ones: the posterior toes are of greater length than those of the anterior extremities. A crest of elevated strongly-compressed scales, often curved in a posterior direction, arises behind the head, and is continued along the mesial line of

* Report on British Fossil Reptiles.

the back to the end of the tail, diminishing as the extremity of the latter is approached, and producing a serrated appearance throughout its extent. This saw-like back, joined to the gular pouch and extraordinarily-shaped head, defended by large scaly plates of different forms, gives these animals a formidable aspect, especially when they have attained to their full growth, which frequently reaches five feet where they have not been disturbed, but does not often exceed that length.

The geographical distribution of the Guanas extends over a great part of South America and the West India islands. Although they occasionally eat eggs and insects in a wild state, and in captivity have been known to feed on the entrails of fowls, their ordinary food consists of buds, leaves, flowers, and fruits, for the cropping of which their numerous teeth, which may be compared to small lancets, terminating in broad blades with minutely serrated edges, are admirably adapted. As this diet leads the Guana to the trees, both form and colour conjoin to aid in securing its safety; the first enabling it to climb and stand firm on the branches, and the second going far towards concealing it in its leafy haunt. The long, slender, serrated, sharp-clawed toes and lengthened flexible tail, here come into play; and the green, bluish, or slaty hue of the upper part of the body, together with the yellowish green or brownish of the under parts, harmonize with its situation. Sometimes there are brown stripes or yellowedged zigzags on the sides of the body; sometimes there is an oblique yellow line on the forepart of the shoulder; some are dotted with brown, the limbs of others are mottled with brown on a blackish ground, and the tail is generally annulated with alternate large brown and green or yellowish rings. These variations are, however, in strict keeping with its sylvan habits.

The Guanas take well to the water in their natural state, and swim with ease and tolerable rapidity. We have seen one in this country perform this feat more than once. The animal entered the pond belonging to the inclosure in which it was kept of its own accord: the motion was easy and graceful, and the long flexible tail appeared to be the principal, if not the only instrument by whose oar-like but sinuous action progression was effected. We have also seen a Guana feeding on the leaves of the common kidney bean, to which plant it had resorted after refusing insects and other animal food. The colour of this Guana was a beautiful green. The leaves were assisted into the mouth by the fleshy tongue, and from the very short time they remained there must have been transmitted to the stomach but little comminuted by the teeth, whose services were evidently more applied to prehension and cropping than mastication. These animals are oviparous: their eggs are round, with a

thinner shell, or rather tegument-for it is tough, not brittle,than that of those of the common poultry, but with a white and yolk resembling that of a hen's egg in flavour. Nor is this the only delicacy supplied by the uncouth-looking Guanas. They become very fat upon their wholesome diet, and are much sought after for their flesh, which is white as that of a chicken, and equal if not superior to it, when properly offered to the palate. The old authors confine their cookery to boiling and frying: thus Piso says that they love to feed on fruits and eggs, whence they derive much fat, and the whitish flesh "quæ elixa vel frixa inter delicias expetita, nec gallinaceis pullis cedit."

The same learned Amsterdam physician condescends to give a receipt for dressing their eggs in water, but without either oil or butter "quæ addita aqua, non oleo aut butyro friguntur;" a method of frying which does not appear to have occurred to Dr. Kitchener. Modern refinement, however, soon discovered that Guana, to be eaten in perfection, should be presented in the savoury and delicate shape of a fricassee.

A few words further in illustration of the existing Guanas from eye-witnesses, whose works are not in the hands of every body.

Sir Hans Sloane gives the following account of an attempt to bring some of the reptiles of Jamaica to England:

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Though I foresaw the difficulties, yet I had an intention to try to bring with me from Jamaica some uncommon creatures alive: such as a large yellow snake, seven feet long, a Guana, or great lizard, a crocodile, &c. I had the snake tamed by an Indian, whom it would follow, as a dog would his master, and after it was delivered to me I kept it in a large earthen jar, such as are for keeping the best water for the commanders of ships during their voyages, covering its mouth with two boards, and laying weights upon them. I had it fed every day by the guts and garbage of fowl, etc., put into the jar from the kitchen. Thus it liv'd for some time, when being weary of its confinement, it shov'd asunder the two boards on the mouth of the jar, and got up to the top of a large house, wherein lay footmen and other domesticks of her Grace the Duchess of Albemarle, who being afraid to lie down in such company, shot my snake dead. It seem'd before this disaster to be very well pleas'd with its situation, being in a part of the house which was filled with rats, which are the most pleasing food for these sort of serpents. 'Tis upon this account that the European nations inhabiting the countries producing sugar do not molest these creatures, because they destroy the rats (which came originally from ships cast away on the coast, &c.) which multiply strangely there, and do infinite mischief to the sugar canes, not only eating them, but spoiling the