Whether the glittering iridescent tints and singular ornaments for which this family is famous result from the cumulative process of conscious or voluntary sexual selection, as Darwin thought, or are merely the outcome of a superabundant vitality, as Dr. A. R.. Wallace so strongly maintains, is a question which science has not yet answered satisfactorily. The tendency to or habit of varying in the direction of rich colouring and beautiful or fantastic ornament, might, for all we know to the contrary, have descended to humming-birds from some diminutive, curiously-shaped, bright-tinted, flying reptile of arboreal habits that lived in some far-off epoch in the world's history. It is not, at all events, maintained by anyone that _all_ birds sprang originally from one reptilian stock; and the true position of humming-birds in a natural classification has not yet been settled, for no intermediate forms exist connecting them with any other group, To the ordinary mind they appear utterly unlike all other feathered creatures, and as much entitled to stand apart as, for instance, the pigeon and ostrich families. It has been maintained by some writers that they are anatomically related to the swifts, although the differences separating the two families appear so great as almost to stagger belief in this notion. Now, however, the very latest authority on this subject, Dr. Schufeldt, has come to the conclusion that swifts are only greatly modified Passeres, and that the humming-birds should form an order by themselves.