What shall be said of the next figure that crosses the tragic stage, during this age of tyrant prodigies? The Iguanodon—a gigantic herbivorous lizard—is related to a family of harmless creatures (_Iguana_), which swarm in the West Indies, and in all the tropical forests of America, in certain peculiarities of the teeth greatly differing from those of other reptiles. The largest of living Iguanas, do not exceed five feet in length: the extinct genus attained a longitude of upward of twenty-eight to thirty feet. The caudal member was about thirteen, head three, trunk with sacrum twelve, and the girth of the body about fifteen feet. The teeth resemble the teeth of the rhinoceros as to bulk and general appearance, and, consisting as they do of incisors and molars, were recognized to belong to the order of herbivorous quadrupeds. The thigh-bone exceeds that of the largest-sized elephant, being from four to five feet in height, and presenting a circumference of nearly two feet in its smallest part. This animal, at its first discovery, was supposed to have attained the exaggerated proportions of nearly a hundred feet in length. But even under the reduced dimensions and more accurate deductions of Professor Owen, confirmed by those of Dr. Mantell, there is still size sufficient, as well as peculiarities of structure, to lead us to regard it as one of the wonders of geology. One femur of a recently-discovered Iguanodon is twenty-seven inches in circumference, and must have been nearly five feet in length; and a tibia, found with the same, is four feet long. Dr. Melville has established the important physiological fact, that the cervical and anterior dorsal vertebræ were convexo-concave,—that is, convex in front and concave behind, as in the existing pachyderms; while the reverse form, the concavo-convex, predominates in the existing crocodilians and lizards. It is farther established, that in the Iguanodon, as in many fossil and recent reptiles, the anterior extremities were much shorter and less bulky than the posterior. As in the existing family, so in the extinct, the huge body was ornamented with a horn of bone which projected from the nose. This nasal organ seems to have been worn more for decoration than for use; unless, perhaps, to assist in perforating its way through the thickets of vegetation on which it subsisted, to push aside an unwelcome intruder upon his pasturage, or as a mere set-off against the unprecedented length of tail. Imagine a herd of these monsters feeding in a prairie—the denizens of a period when all things partook of the gigantic! “The concurrence of peculiarities so remarkable,” says Buckland, “as the union of this nasal horn with a mode of dentition of which there is no example, except in the Iguanas, affords one of the many proofs of the universality of the laws of co-existence, which prevailed no less constantly throughout the extinct genera and species