Page:Popular Science Monthly Volume 46.djvu/781

Rh existed in bygone ages, and had been the parents of a varied and varying offspring—our fellow-creatures of to-day."

"Classification for the first time was something more than the expression of a fancy. Not that it had not also its imaginative side. Men's minds began to figure to themselves the original type of some well-marked genus or family of birds. They could even discern dimly some generalized stock whence had descended whole groups that now differed strangely in habits and appearance—their discernment aided, may be, by some isolated form which yet retained undeniable traces of a primitive structure. More dimly still, visions of what the first bird may have been like could be reasonably entertained; and passing even to a higher antiquity, the reptilian parent, whence all birds have sprung, was brought within reach of man's consciousness."

When all this came to pass it was those very isolated forms—the so-called "outliers" among birds—to which Prof. Newton alludes in the last paragraph, that then came to be regarded with a peculiar interest by the scientific ornithologist; and, although at the present writing there is by no means a unanimity of opinion as to the position many of them occupy in the system, they nevertheless at once threw a powerful light upon the whole field of ornithology. Ornithotomists everywhere, the world over, carefully investigated their anatomical structure, and groups of birds long thought to be widely separated were seen to be, through these forms, more or less nearly related to each other, and the fact as a whole was demonstrated beyond all cavil that the class Aves had arisen from primitive reptilian stock.

Without further dwelling upon this phase of the subject, we will say here that it is the object of the present article to call attention to some of the more prominent species of birds that, to a greater or less extent, are considered to represent these "outliers" of the class. Although hardly to be regarded as belonging among them, the very interesting group of forms that we commonly designate among them as the "ostrich group" are important, inasmuch as through them we are enabled, by the aid of many fossil and subfossil types, to trace birds directly back to some of their reptilian stock. Among the existing ostrichlike types we have the Apteryx or kiwi, of New Zealand, a bird now supposed by some of our best authorities to have kinship with the rails. Then there are the emeus and cassowaries, rhea, or the South American representative of the ostriches, and, lastly, the true ostriches themselves.