14 PTERYLOGRAPHY. 



and nearly pennaceous barbicels, and thus form a transition towards contour-feathers. 1 As regards 

 their structure down-feathers have either a simple shaft, or combined with this an aftershaft, when 

 the contour-feathers are likewise furnished with the latter, as, for example, in the diurnal rapacious 

 birds, the Cranes, the Herons, and others; or they are umbelliform, in which case the shaft is entirely 

 wanting, and the barbs are seated on the upper extremity of the tube, as, for example, in 

 Pelecanus. I shall speak hereafter of the peculiar powder-down-feathers, which continually 

 produce a dusty matter. 



The downy covering of newly-hatched young birds consists, according to some authors, of 

 down-feathers, and, according to others, of hairs ; in most birds, however, it is formed neither of 

 one nor the other, but solely of early-deciduous, down-like, or setiform processes, seated upon the 

 apices of the first-formed barbs of contour-feathers, or even of down-feathers. It is only in the 

 Unyuirosfres that the nest-clothing consists of true down-feathers furnished with a shaft and 

 tube. But these down-feathers are stiffer, in all parts, than the subsequent ones, and their 

 barbules are remarkably thin. They exhibit no knots, or very small ones, and these bent 

 alternately in different directions. 



3. The semiplumes hold, as it were, a middle place between the down- and contour-feathers, 

 possessing the larger and more rigid stem of the latter, and the downy barbs and barbules of the 

 former. They never stand, like the true down-feathers, between contour-feathers, but at the 

 margins or extremities of the feather-tracts, where they complete the series of contour-feathers, or 

 entirely take their place. They even form tracts without contour-feathers, when they stand 

 closer together. They are, nevertheless, covered by contour-feathers, and withdrawn from the light. 

 Frequently they have an aftershaft when this also occurs in the contour-feathers ; they are then 

 distinguished from the neighbouring contour-feathers only by the want of the pennaceous apex. 

 Others are more like down-feathers. They are largest in some Storks, as, for example, in 

 C. aryala and C. marabu, in which they are seated beneath the lower tail-coverts, and are often 

 employed as ornaments by our ladies ; they also occur in the same situation in Falco albicilla. 



4. The filoplumes (Plate I, fig. 7) are very strikingly distinguished from the other three 

 kinds of feathers by their peculiar position, their extraordinary slenderness, and by the entire 

 deficiency or very small size of their vane. At the same time they are, as it were, associated 

 with the contour-feathers, one, or even two, filoplumes standing quite close to every contour- 

 feather of the head, neck, and trunk, apparently issuing almost out of the same pouch of the 

 skin. More rarely, as in the Herons and Unguirostres, several filoplumes (sometimes as many as 

 ten) stand near each contour-feather. In their structure they belong to the filamentous type, and 

 no other occurs in them, except that sometimes, for example in some gallinaceous birds, they have 

 downy barbs and barbules at the base. 2 The stem is usually so thin that it can scarcely be seen 

 by the naked eye. In the Cassowaries alone it is much thicker, and, contrary to the general rule, 

 greatly compressed. It is, however, always rigid, straight, long, and filiform, and has a very 



1 Perhaps these surface down-feathers (Licht-dunen) should be referred to the contour-feathers, 

 under the assumption that the downy part, which in most contour-feathers occurs only at the inferior 

 extremity, ascends in these to the extreme apex. 



2 A filoplume of this kind found in the common fowl (Gallus Bankiva domestica), is figured 

 by HEUSINGEK (' Histologie' I, tab. iii, figs. 1 and 2). Our figure (PI. I, fig. 7) shows no downy barbs, 

 and is taken from the feather of a Goose. 



