ORNITHOLOGY OF SECTION D, 1850. 
while those on the proximal side are simple. But it is remarkable, 
that in these deciduous filaments which I am describing, both series 
of barbules are furnished with hooked barbicels. The object of these 
is obviously to embrace the barbules of the feather-barbs, during 
the attachment of the latter to the filament, and as these barbules 
are attached to both sides of the filament, it is requisite that the 
filament should be provided with a double series of hooks. 
The object of this singular structure is probably the protection of 
the feather-barbs during the course of their development. But why 
80 complex and elaborate an arrangement should be confined to two 
feathers only in the bird, and to one species of bird only (as far as 
is yet known), is one of the many questions of natural science which 
must probably remain unanswered. 
Baplanation of the Plate. 
Fig. 1.—Under view of basal portion of one of the submedial rec- 
trices of Vidua paradisea, in a half developed state. 
a. Exterior web; b. interior web; cc. serrated margin; d. free 
portion of filament; ef. portion of filament attached to mar- 
gin of interior web ; fg. portion attached to both webs; h. barbs 
of exterior web recently detached from the filament and not 
yet incorporated into the web; ¢ membranous sheath surround- 
ing the immature barbs. 
Fig, 2.—Portion of filament magnified, showing the alternating 
tufts of barbules on each side. 
gj. 3.—4_AY Portion of filament lplly magnified, with. portions 
of barbs attached as in Fig. 1, f.g. 
aa. Filament-barbules, forming two series of tufts, both of 
which are furnished with hooked barbicels; 6b. feather-barbs, 
belonging to the two opposite webs of the feather, connected 
at their distal extremities to opposite sides of the filament ; 
cece. barbules of the distal side of the barbs, furnished with 
hooked barbicels ; ddd. barbules of the proximal side of the 
barb, devoid of barbicels, or furnished with only a very few 
Simple ones, 
ct 
