[Illustration: FIG. 74. RESTORATION OF THE SKELETON OF _ORNITHOSTOMA INGENS_ (MARSH) From the Niobrara Cretaceous of Western Kansas. Made by Professor Williston. The original has a spread of wing of about 19 feet 4 inches. Fragments of larger individuals are preserved at Munich] In the restoration which Professor Williston has made the wing metacarpal is long, and in the shortest specimen measures 1 foot 7 inches, and in the longest 1 foot 8 inches. This is exactly equal to the length of the first phalange of the wing finger. The second wing finger bone is 3 inches shorter, the third is little more than half the length of the first, while the fourth is only 6-3/4 inches long, showing a rapid shortening of the bones, a condition which may have characterised all the Cretaceous Pterodactyles. The short humerus, about 1 foot long, and the fore-arm, which is scarcely longer, are also characteristic proportions of Ornithostoma or Pteranodon, as known from the American specimens. Professor Williston gives no details of the remarkable tail, beyond saying that the tail is small and short, and that the vertebræ are flat at the ends, without transverse processes. In the restoration the tail is shorter than in the short-tailed species from the Lithographic Slate, and unlike the tail in Ornithocheirus. This is the succession of Pterodactyles in geological time. Their history is like that of the human race. In the most ancient nations man's life comes upon us already fully organised. The Pterodactyles begin, so far as isolated bones are concerned, in the Rhætic strata; perhaps in the Muschelkalk or middle division of the Trias. And from the beginning of the Secondary time they live on with but little diversity in important and characteristic structures, and so far as habit goes, the great Pterodactyles of the Upper Chalk of England cannot be said to be more highly organised than the earlier stiff-tailed genera of the Lias or the Oolites. There is nothing like evolution. No modification such as that which derives the one-toed horse or the two-toed ox from ancestors with a larger number of digits. On the other hand, there is little, if any, evidence of degeneration. The later Pterodactyles do not appear to have lost much, although the tail in some of the Solenhofen genera may be degenerate when compared with the long tail of Dimorphodon; but the short-tailed types are found side by side with the long-tailed Rhamphorhynchus. The absence of teeth may be regarded as degeneration, for they have presumably become lost, in the same way that Birds now existing have lost the teeth which characterised the fossil birds--Ichthyornis of the American Greensand, and Archæopteryx of the Upper Oolites of Bavaria. But just as some of the earlier Pterodactyles have no teeth at the extremity of the jaw, such as Dorygnathus and Rhamphorhynchus, so the loss of teeth may have extended backward till the jaws became toothless.