1916] Chandler: Structure of Feathers 371 
Hydrocorax, but in neither are the barbules as large and heavy. 
The breast feathers and looser back feathers are of the same type 
as other coraciiformes, but the barbs are very loose distally, soon 
giving way to a downy structure. 
Striges—The owls are characterized by remarkable softness of 
their plumage, which, as already shown by Mascha (1904), is brought 
about by an even more remarkable modification in structure of 
barbules. 
In Bubo maximus, on inner vane of remiges, distal barbules 
(pl. 32, fig. 84a) have base of typical coraciid type, with sinuate 
ventral contour and small, slender, ventral teeth, but pennulum 
excessively elongated, frequently reaching a length of over 2 mm., 
when the base is only about 0.3 mm., being, therefore, nearly seven 
times as long. The hooklets, 5 in number, very slender, increasing 
in length to a remarkable degree from the proximal to the distal 
ones. As shown by Mascha (1904), the pennulum is flattened 
dorso-ventrally and furnished with a complete double series of both 
dorsal and ventral cilia, which, however, are curved in such a way 
that their tips project laterally (pl. 32, fig. 84a). Both dorsal and 
ventral cilia slender and flexible, the ventral ones, especially on the 
proximal portion of the pennulum, longer than dorsal ones, the 
proximal ones of which are not at all enlarged or modified. The 
proximal barbules (pl. 32, fig. 84b) have an elongate, narrow base, 
long, slender ventral teeth which, however, le in close juxtaposition 
and so are inconspicuous, and an exceedingly long filamentous pen- 
nulum, almost as long as that of the distal barbules. 
On the outer vane distal barbules differ in that pennulum is 
much stouter and considerably shorter, with the dorsal cilia entirely 
absent. Proximal barbules have very slender base and long’ fila- 
mentous but moderately heavy pennulum with a series of very 
slender, delicate and inconspicuous ventral cilia. Comblike outer 
margin of outer vane due to curving back of the rami, with an 
accompanying shortening and stiffening of the barbules and loss of 
the interlocking apparatus. Plate 32, figure 84c represents a distal 
barbule from this region of barb. 
Body feathers of owls resemble remiges in great length of bar- 
bules. The delicate, semi-transparent character, especially of breast 
feathers, is due to wide spacing of barbs and barbules, the former 
set about 15 per centimeter on each side, the latter 8 or 9 and 12 
to 15 per millimeter on proximal and distal vanules respectively. 
