When we speak of a quadruped, the very name seems to carry the idea of an animal covered with hair; as when we mention a bird, or fish, feathers and scales present themselves to our imagination, and seem to be inseparable attributes of those beings: yet Nature, as if willing to deviate from this characteristic uniformity, and to elude our views, offers herself, contrary to our general ideas, and in contradiction to our denominations and characters, and amazes more by her exceptions than by her laws. Quadrupeds, which we look upon as the first class of living nature, and who are, next to man, the most remarkable beings of this world, are neither superior in every thing, nor separated by constant attributes from all other animals. The first of those characters which constitutes their name, and which consists in having four feet, is common to lizards, frogs, &c. which differ, however, from quadrupeds in so many other respects, as to make them be considered as a separate class. The second general property, to produce young alive, is not peculiar to quadrupeds, since it is also common with cetaceous animals. And the third attribute, which seems the less equivocal, as it is the most apparent, that of being covered with hair, exists not in several species which cannot be excluded from the class of quadrupeds, since this single characteristic excepted, they are like them in all other respects: and, as these exceptions of nature are but gradations calculated to join in a general chain, the links of the most distant beings, we should seize these singular relations as they offer themselves to our view. The armadillos, instead of hair, are covered, like turtles, craw-fish, &c. with a solid crust. The manis is armed with scales like fish; the porcupine carries a sort of prickly feathers, the quill of which is like that of the birds. Thus in the class of quadrupeds, and in the most constant characteristic of these animals, that of being covered with hairs, Nature varies in bringing them near the three different classes of birds, fishes, and the crustaceous kinds. We must be cautious then in judging of the nature of beings by one single character, as that would always lead us into error; even two or three characters, though general, are often insufficient, and it is only, as we have often repeated, by the union of all the attributes, and by enumerating all the characters, that we can judge of the essential qualities of the productions of nature. A good description without definitions, an exposition more exact on the differences than the analogies, a particular attention to exceptions and almost imperceptible gradations, are the true rules, and I dare assert, the only means of estimating nature. If the time lost in forming definitions had been employed in making good descriptions, we should not at this day have found Natural History in its infancy; we should have had less trouble in taking off her bawbles, disentangling