Who would for a moment imagine that all this grandiloquence is bestowed upon an animal, which is so far from being fierce and untameable, that young ones, taken and reared with ordinary cattle, become, even in the first generation, as tame as domestic animals? [See account of Chillingham White Cattle, p. 140.] For a more complete satisfaction of his thought, the reader is referred to Mr. Swainson's volume "On the Natural History and Classification of Quadrupeds," p. 274, where he has given us an incoherent abstract of Colonel Smith's article on the _Bovinae_, without, however, making the least attempt to verify the statements there recorded. The descriptions and characteristics are avowedly Colonel Smith's; but, in justice to the latter gentleman, it must be added, that the disquisitions on the circular succession of forms, and the analogical relations, are entirely Mr. Swainson's. ON SPECIES AND VARIETY. What constitutes a species? And how far do the limits of varieties extend? Cuvier, who is, perhaps, the best authority we can have upon this subject, in defining a species, says:--_A species comprehends all the individuals which descend from each other or from a common parentage, and those which resemble them as much as they do each other._ Thus, the different races which they have generated from them are considered as varieties but of one species. Our observations, therefore, respecting the differences between the ancestors and the descendants, are the only rules by which we can judge on this subject; all other considerations being merely hypothetical, and destitute of proof. Taking the word _variety_ in this limited sense, we observe that the differences which constitute this variety depend upon determinate circumstances, and that their extent increases in proportion to the intensity of the circumstances which occasion them. Upon these principles it is obvious, that the most superficial characters are the most variable. Thus colour depends much upon light; thickness of hair upon heat; size upon abundance of food, &c. In wild animals, however, these varieties are greatly limited by the natural habits of the animal, which does not willingly migrate from the places where it finds, in sufficient quantity, what is necessary for the support of its species, and does not even extend its haunts to any great distances, unless it also finds all these circumstances conjoined. Thus, although the Wolf and the Fox inhabit all the climates from the torrid to the frigid zone, we hardly find any other differences among them, through the whole of that vast space, than a little more or less beauty in their furs. The more savage animals, especially the carnivorous, being confined within narrower limits, vary still less; and the only difference between the Hyaena of Persia and that of Morocco, consists in a thicker or a thinner mane.