Yet the American who asks for a model to work by in his investigations will find a great deal more than the "North American Testudinata" in the part to which that title is prefixed. The principles of classification exemplified, the methods of description illustrated, the rules of nomenclature tested,--what matter is it whether the _gran maestro_ has chosen this or that string to play the air upon, when each has compass enough for all its melody? Still more forcibly does this comment apply to the elaborate and ample division of the work embracing the Embryology of the Turtle. He who has mastered the details of this section has at his feet the whole broad realm of which this province holds one of the key-fortresses. _Ex testudine naturam_. We are unwilling to speak of the illustrations comparatively without more extended means of judgment than we have at hand. But that they are of superlative excellence, brilliant, delicate, accurate, life-like, and nature-like, is what none will dispute. Look at these turtles, models of real-estate owners as they are, Observe No. 13, Plate IV.,--"Chelydra Serpentina,"--"snapper", or "snappin' turtle," in the vernacular. He is out collecting rents from the naked-skinned reptiles, his brethren; in default thereof, taking the bodies of the aforesaid. Or behold No. 5, Plate VI., bewailing the wretchedness of those who have no roofs to cover them. Or No. 2, of the same plate, bestowing an archiepiscopal benediction on the houseless multitudes, before he retires for the night to slumber between his tessellated floor and his frescoed ceiling. Of the smooth, white eggs, with their rounded reliefs and tenderly graduated light and shadow, all eyes are judges. But of the exquisite figures showing the various stages of development and the details of structural arrangement, the uninitiated must take the opinions of a microscopic expert: and if they will accept our testimony as that of one not unfamiliar with the instrument and the mysteries it reveals, we can assure them that these figures are of supreme excellence. The hazy semitransparency of the embryonic tissues, the halos, the granules, the globules, the cell-walls, the delicate membranous expansions, the vascular webs, are expressed with purity, softness, freedom, and a conscientiousness which reminds us of Donne's microscopic daguerreotypes, while in many points the views are literally truer to nature,--just as a sculptor's bust of a living person is often more really like him in character than a cast moulded on his features. We have attempted to give a slight idea of the contents of these two volumes, in the compass of a few pages. We have called the reader's attention to various points of special interest, as we were going along. It remains to make such comments as suggest themselves to us, either in our character of "the scholiast," or in our own right as a freed citizen of the intellectual as well as the political republic.