"Unless when caught young, it is very difficult to induce these reptiles to feed in confinement, and particularly when watched. Their disposition is sulky and savage, and I have known some of them," continues Lieutenant Tyler, "to die in confinement from starvation, rather than feed. This has caused me to try the following plan, which I find very successful, of affording them nourishment:--I hold them by the lower part of the body with one hand, and with the other I irritate them until they open their mouth and attempt to bite, when I insert food; and by annoying them in this way, I have not only made them eat their natural food, but I have killed some of them by forcing them to eat corn and leaves, which appear to have disagreed with them. By some of the natives this Iguana is said to eat Lizards and insects; but I have opened several, and I have never succeeded in finding any but vegetable matter in the stomach." Of the habits of a kindred species of Iguana, the _Cyclura lophura_, inhabiting Jamaica, Mr. Gosse has given an elaborate description; and he tells us that the gular pouch in the _Iguanidæ_ "is _extensible_, but not _inflatable_," as is the current opinion. Holbrook and others have remarked the same; and Professor Thomas Bell describes the fold of skin as being drawn down by a peculiar arrangement of the lingual bone, and a singular cartilage fixed to it and attached also to the skin. These parts are moved by delicate muscles, so that, when the cartilage is drawn down, the skin of course is distended, and follows it "in the same way that the silk is stretched over the whalebone of an umbrella." "In fact the skin," writes Professor Holbrook, "when distended in life by the animal, does not resemble the inflated vocal sacs of the Frogs and Toads, which are round, but looks like a fold of the skin, pinched and drawn down, the two portions of it being in contact, like a dew-lap." It appears that the _Cyclura_, also, is exclusively herbivorous; and Mr. Gosse remarks upon the severe wounds which it inflicts upon Dogs with its sharply-serrated tail. In general, the larger species of this family are solely vegetable-feeders, while the smaller kinds (such as the Anoles) are more or less insectivorous; and there are some, of intermediate size, which even prey occasionally upon the kindred Anoles and other small animals. The genera of these reptiles are exceedingly numerous, as we have seen, and amongst so many there must be considerable variety in the habits; but we can only notice a very few of them. Within the limited area of the small archipelago of the Galapagos, situated on 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 of the "Voyage of H.M.S. _Beagle_." One of them is particularly so, because, as that naturalist observes, it is the only existing