From what has been said the reader will understand how it is possible to make an approximately accurate picture of extinct animals as they appeared in life—approximately accurate, never absolutely so. The flesh and other soft parts of an animal are never petrified, though it is a common belief that they may be. Petrified men and women are still occasionally shown in cheap museums, but they are always frauds. Many times has the writer been called upon to express an opinion as to the nature of some concretion which the discoverer was sure was a petrified snake, turtle, or even some part of the human body, because of fancied resemblances in shape and size. Not too emphatically can it be said that anything dug from the earth having the shape of a living animal and alleged to be petrified is either an accidental resemblance or a deliberate humbug—if we except such extraordinary casts as those of Pompeii. The Cardiff Giant and the Muldoon are still fresh in the memory of some of us. There have been a few instances where flesh has been preserved in the North, frozen for thousands of years, but frozen fossils are very different from petrified fossils. Flesh decays before it possibly can be petrified, and only rarely is the residue of flesh, tendons, and skin, that is, the carbon and mineral matters, preserved. [Illustration: FIG. 2.—Removing a specimen of fish in a block from the chalk of western Kansas.] One may sometimes restore extinct animals as in life, knowing fully the shape and structure of the skeleton, and still be far from the real truth. All elephants of the present time have a bare or nearly bare skin. If all that we knew of the extinct mammoth were derived from the skeleton we should never have suspected that the creature was clothed during life with long and abundant hair, such as has been found with the frozen bodies in Siberia. Nor should we suspect that the dromedary and Bactrian camels of today have large masses of fat on their backs, if we knew only their skeletons. It must therefore be remembered that all restorations of extinct animals, representing them as in life, are merely the sum of our knowledge concerning them, as close approximations to the real truth as it is possible to make. Or, rather, they should be such approximations; unfortunately many such restorations have been made by artists wholly unacquainted with the anatomy of the creatures they attempt to represent, often adorned with appendages drawn from a too vivid imagination. CHAPTER II CLASSIFICATION OF REPTILES