< Page:Popular Science Monthly Volume 18.djvu
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THE POPULAR SCIENCE MONTHLY.

recalled by different portions of the skeleton. Among recent birds, the peculiar legs and feet of Hesperornis find their nearest analogues in the Grebes of the genus Podiceps. They were admirably adapted for propulsion in water, but scarcely served for walking on land. Locomotion must have been entirely performed by the posterior limbs—a peculiarity which distinguishes Hesperornis from all other aquatic birds, recent or fossil. The tail appears to have been composed of twelve vertebræ, unique in their peculiar, widely-extended, transverse processes and depressed horizontal plowshare bone. Broad and flat, somewhat like that of the beaver, it must have been a powerful instrument in steering the bird through the water. The second part is devoted to a description of the remains which have been found of birds belonging to a second order of Odontornithes, termed Odontotormæ. Unlike Hesperornis, they seem to have been all of comparatively small size and to have possessed powerful wings, but very small legs and feet. From that contemporaneous form, and from all other known birds recent and fossil, they are distinguished by certain types of structure which point back to a very lowly ancestry, lower even than the reptile. Their bones, being mostly air-filled, would enable the carcasses to float on water until, by decay or the rapacity of other animals, they were separated and dispersed. Hence skeletons of these flying birds are less entire than those of the massive-boned Hesperornis. Nevertheless, the remains of no fewer than seventy-seven different individuals have been disinterred. These are included in two well-marked genera, Ichthyornis and Apatornis, and were all small birds, reminding us by their strong wings and delicate legs and feet of the Terns, like which they were probably also aquatic in habit. Besides the reptilian skull and teeth, the birds of this second order were marked by the character of their vertebræ, which in their biconcave structure recall those of fishes. This is the more remarkable, as in Hesperornis the vertebræ are like those of modern birds. Yet these two utterly dissimilar types were contemporaries, and their remains have been preserved in the same strata. Mr. Marsh points out that the transition between the two vertebral types may be traced even in the skeleton of Ichthyornis itself, where the third cervical vertebra presents a modification in which the ordinary avian saddle-shaped form appears as it were in the act of development from the biconcave ichthyic form.

This memoir and those which will succeed it have a weighty interest as contributions to the doctrine of organic evolution. There is no other possible way of explaining the numerous facts than by this theory. Professor Marsh's discoveries are new demonstrative proofs of the law, which he has done more to confirm by these fossil revelations than any other living man, or all contemporary naturalists put together.

It remains only to add that the volume in all its elements—paper, printing, drawing, and engraving—is superb. The illustrations, all executed in New Haven, and by the most skillful hands the world affords, are the perfection of art. Professor Geikie pays them the following high but deserving compliment: "They are strictly and rigidly scientific diagrams, wherein every bone and part of a bone is made to stand out so clearly that it would not be difficult to mold a good model of the skeleton from the plates alone. And yet, with this faithfulness to the chief aim of the illustrations, there is combined an artistic finish which has made each plate a kind of finished picture." Should the series of memoirs of the Peabody Museum of Yale College, of which this is the first, be carried out on a scale and with a thoroughness here attained, it will form one of the great scientific monuments of the century.

German Thought. By Karl Hillebrand. New York: Henry Holt & Co. 1880. Pp. 298. Price, $1.75.

In these six lectures before the Royal Institution of Great Britain, Professor Hillebrand has traced in outline the rise of modern German thought and its influence in forming modern German political life. The period covered by his review is that from the Seven Years' war to the death of Goethe, but he glances briefly at the part taken by the other nations in the work of modern culture, as an indispensable preliminary to the subject proper. His review leads him to a consideration of the Italian Renaissance, in which Italy led the way in breaking from the thralldom of mediæval tradition and authority; the reaction against the sensuous view of life that this introduced, which in Spain was expressed by the founding of the Society of Jesus, and in Germany by the Reformation; and the passing to England and Holland, and later to France, of the leadership in the thought and spirit that have made modern Europe. Though Germany held an important place in the initial movement, she took but little part. Professor Hillebrand points out, in the subsequent progress of it. She had been engaged in one of the most notable struggles in history, and came out of it prostrate. The Thirty Years'

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