mal draws in or extends simultaneously with the compression or swelling out of the body when enraged or excited. The portion of the pouch attached to the jaw is inflatable, and food is sometimes retained in it for a considerable period.

This iguana is not averse to water, when not too cold, taking to it only when the sun is shining; in fact, not moving about much at any other time. Its mode of swimming differs from that of other lizards, inasmuch as it places its four legs close by the side of its body, and swims entirely with its tail. It dives with great facility, and remains sometimes for a considerable time under water. The tail is a very valuable limb; for, besides being the sole means of swimming possessed by the animal, it is of great use in climbing trees, and it is a more important weapon of defence, a blow from it being frequently sufficient to inflict a severe wound Vigorous Use of Teeth and Claws.

In fact, this reptile is rather formidable when brought to bay in the woods. It is hunted by the natives with dogs trained for the purpose. The dog, immediately upon scenting it, gives tongue, and, if on the ground, the dog seizes it by the neck, and either kills it or maims it, which makes its capture easy; if in a tree, the iguana is either shaken down-a matter ordinarily of no small difficulty-or the branch is cut off. It is almost useless to attempt to find these reptiles without dogs, as the resemblance of their color to that of the trees which they inhabit prevents them from being easily seen. Few dogs but those accustomed to the sport will touch them, as, in addition to the blows which they inflict with. the tail, they bite and scratch furiously; and when once they lay hold of anything with their teeth, they can only be made to let go by an inducement to bite some more attractive object offered to them. They run into holes when chased, if an opportunity offers, and when their eyes are hidden from view they fancy that their whole body is safely covered. The flesh, particularly of the female, is a great delicacy; it is cooked in various ways, sometimes in a fricassee with the eggs whole, sometimes roasted or stewed. The eggs have a very glutinous consistence.

Within the limited area of the small archipelago of the Gallapagos, situated under the equator about ten degrees west of South America, there are two remarkable species of iguanidæ, of which the habits have 'been described and commented upon by Mr. Darwin in his volume entitled the "Voyage of the Beagle." One of these is particularly so, because, as that naturalist observes, it is the only existing saurian which can properly be said to be a marine animal. In the whole of that group of islands, as he tells us, there is only one rill of fresh water; yet this rep

tile frequents the sea-beaches, and no other parts of the islands. He adds that it is the only known existing lizard that feeds exclusively on aquatic productions.

The sea-guana according to Darwin, is very common on all the islands throughout the archipelago of the Gallapagos. It lives exclusively on the rocky sea-beaches, and is never found-at least, I never saw one-even ten yards inshore. It is a hideous-looking creature, of a dirty black color, stupid and sluggish in its movements. The usual length of

a full-grown one is about a yard, but there are some even four feet long. I have seen a large one which weighed twenty pounds. On the Island of Albemarle they seem to grow to a greater size than on any other. These lizards were occasionally seen some hundred yards from shore swimming about; and Captain Colnett, in his "Voyage," says, "they go out to sea in shoals to fish." With respect to the object, I believe that he is mistaken; but the fact stated on so good an authority cannot be doubted.

When in the water the animal swims with the greatest ease and quick

ness, by a serpentine movement of its body and flattened tail-the legs, during this time, being motionless and closely collapsed on its sides. A seaman on board sank one, with a heavy weight attached to it, thinking thus to kill it directly; but when, an hour afterwards, he drew up the line, the lizard was quite active. Their limbs and strong claws are admirably adapted for crawling over the rugged and fissured masses of lava which everywhere there form the coast. In such situations, a group of six or seven of these ugly reptiles may oftentimes be seen on the black rocks, ¡a few feet above the surf, basking in the sun with outstretched legs. I opened the stomachs of several, continued Mr. Darwin, and in each case found it largely distended with minced sea-weed of that kind which grows in thin foliaceous expansions of a bright green or dull red color. I do not recollect having observed this sea-weed in any quantity on the tidal rocks; and I have reason to believe that it grows at the bottom of the sea, at some little distance from the coast. If such is the case, the object of these animals occasionally going out to sea is explained.

The food of this lizard, equally with its compressed form of tail, and the certain fact of its having been seen voluntarily swimming out at sea, absolutely prove its aquatic habits; nevertheless, as we are told by Darwin, there is in this respect one strange anomaly, namely, that when frightened it will not enter the water. From this cause, it is easy to drive these lizards down to any little point overhanging the sea, where they will sooner allow a person to catch hold of their tail than jump into the water. They do not seem to have any notion of biting; but when much frightened they squirt a drop of fluid from each nostril.

Darwin's Experience with a Lizard.

One day I carried one to a deep pool left by the retiring tide, and threw it in several times as far as I was able. It invariably returned in a direct line to the spot where I stood. It swam near the bottom, with a very graceful and rapid movement, and occasionally aided itself over the uneven ground with its feet. As soon as it arrived near the margin, but still being under the water, it either tried to conceal itself in the tufts of seaweed, or it entered some crevice. When it thought the danger was passed, it crawled out on the dry rocks, and shuffled away as quickly as it could. I several times caught this same lizard by driving it down to a point, and, though possessed of such perfect powers of diving and swimming, nothing would induce it to enter the water; and as often as I threw it in it returned in the manner above described. Perhaps this singular piece of apparent stupidity may be accounted for by the circumstance that this reptile has no enemy whatever on shore, whereas at sea it must often

fall a prey to the numerous sharks. Hence, probably urged by a fixed and hereditary instinct that the shore is its place of safety, whatever the emergency may be, it there takes refuge. I asked several of the inhabitants if they knew where it laid its eggs; they said, that although well acquainted with the eggs of the other kind, they had not the least knowledge of the manner in which this species is propagated.

These lizards are very quick in all motions, and climb with astonishing agility. The females are smaller than the males; their appearance is more gentle and pleasing. They are seen gathering along the beach about two months after the end of winter for the purpose of depositing their eggs in the sand of the sea-shore.

A Gallant Defense.

During the spring of the year the male exhibits great attachment. towards the female. He defends her even with fury, attacking every animal that seems inclined to injure her, and sometimes fastens his teeth to the enemy so firmly, that it is necessary either to kill him orto beat him on the nose to make him quit his hold. It cannot without difficulty be killed with blows or even by gunshot wounds, but it dies. almost instantly if even a straw is put up its nostrils.

These animals are found in a great number on the Galapagos Islands, where they live on the rocks only a few feet distant from the sea. They are excellent swimmers by a snake-like movement of the body and tail, but never using their feet, which are laid closely to the body and never moved. It is a singular fact that when alarmed they seek refuge on the rocks and not in the water, although they are more or less aquatic animals.

Electric Telegraph Suggested by the Frog.

The foot of a frog is often selected for observation in the microscope, as beautifully illustrating the circulation of the blood. It is also worthy of remembrance that Galvani, Professor of Anatomy at Bologna, remarked on one occasion that when the limbs or nerves of a frog were put into communication with the muscles of the thigh, by means of an electric conductor, the limbs were violently convulsed. Thus he discovered a force hitherto unknown, which he called animal electricity. But Volta, another Italian, observing that the effects were far greater when the connecting medium consisted of two different kinds of metals, inferred that the principle of excitation existed in the metals, and not in the nerves of the animal. He therefore argued that by their contact there was developed a small quantity of the electric fluid, which, being transmitted through the organs of the frog, produced the convulsive movements. And