But as the "Arundines Cami," musical as they are, have lent no prelude to these harmonies of science, we must say in a few plain words of prose our own first thought as to the work the commencement of which lies before us. We believe, that, if completed according to its promise, it is to be one of the monumental labors of our century. Comparisons are not to be lightly instituted, and especially under circumstances that do not allow a fair survey of the whole field from which the objects to be compared are to be taken. We suppose, however, it will be conceded that the sunset continent has never witnessed anything like the inception of this mighty task in the way of systematic natural science. And if, since Cuvier, the greatest of naturalists, as Mr. Agassiz considers him, slept with the fossils to which he had given life, there has been any other student of Nature who has attempted a task so immense, with the same union of observing, reflecting, analyzing, and coördinating power, we cannot name him. Our civilization has a right to be proud of such an accession to its thinking and laboring constituency; it is also bound to be grateful for it, and to express its gratitude. It is just one hundred years since another Swiss, the magnificent Albert von Haller, gave to the world the first volume of the "Elementa Physiologiae Corporis Humani." Nine years afterwards, in 1766, the last of the eight volumes appeared; and the vast structure, which embodied his untiring study of Nature, his world-wide erudition, his deepest thought, his highest imaginings, his holiest aspirations, stood, like the Alps whose shadow fell upon its birthplace, the lovely Lausaune, pride of the Pays de Vaud. The clepsydrae that measure the centuries as they drop from the dizzy cliffs--the glaciers, by the descent of which "time is marked out, as by a shadow on a dial," and which thunder out the high noon of each revolving year with their frozen tongues, as they crack beneath the summer's sun--have registered a new centennial circle, and at the very hour of its completion, Switzerland vindicates her ancient renown in these fair pages, at once pledge and performance, of another of her honored children. May the auspicious omen lead to as happy a conclusion! Lovingly, then, we lay open the generous quarto and look upon its broad, bright title-page. It tells us that we have here the first of a series of "Contributions to the Natural History of the United States of America." We see that one of its three parts embraces the largest generalities of Natural Science, under the head of an "Essay on Classification." We see that the other two parts are devoted to the description and delineation of a single order of Reptilia,--the Testudinata, or "Turtles."