only curved and not hook-like. All these spines are called barbicels. They are upon the lower edge of the barbule; but upon the upper edge are a few shorter and stouter spinelets. As the barbules come off in an oblique direction, it follows that each one of them overlaps a considerable number, in fact five, barbules of the opposite barb. The attachment is by these hooklets, or hamuli, as they are usually termed. The stiff feathers which have this elaborate structure are not found at all in the ostrich-like birds; in them there is no need for a firm surface to catch the air; on the contrary, it would be, if anything, disadvantageous to swift runners, as those birds are. The feathers, therefore, are much reduced in complexity, and in some they consist only of the stem and the barbs. Even in flying birds there are plenty of feathers of a simple structure lying between the stronger contour feathers. These are the soft feathers which are generally spoken of as ‘down.’ Some of them are so reduced as to consist of little more than the stem. The same reduction is seen in the wing feathers of the Cassowary. Along the margin of the wing are a few strong black spines, which are really the quills of the wing feathers with no barbs at all; they consist merely of the stem, which has not dwindled in the least, but is quite as strong as it would be in a feather of use for flying. In a good many birds the contour feathers and the down feathers also have a kind of appendix, known as the aftershaft. This is a sort of supplementary feather arising from the stem just at the point where the barbs begin, and having precisely the structure of a small feather. In the Emu and the Cassowary this aftershaft is fully as large as the main feather; from each stem in these birds arise as it were two feathers. [Illustration: FIGS. 2, 3. (After Wray in ‘Ibis’ for 1887.) B, Barbs; _bp_, proximal barbules; 1, flange; 2, ‘dog-tooth,’ part of flange; 3, overlapping portion.] [Illustration: FIG. 4.--PORTION OF TWO ADJACENT BARBS. (After Wray in ‘Ibis’ for 1887.) B, barbs; _bd_, _bp_, barbules (distal and proximal).]