MASCHA] STRUCTURE OF WING—FEATHERS 9 
tween this and the second secondary ridge (figs. 3, 4). If there are 
more than two secondary ridges in the section, the third and fourth 
are so small and the grooves lying between them so shallow, that 
the position of the fiber-sections relative to them becomes doubtful. 
In surface views one sees parallel lines at the side of the dorsal ridge 
of the secondary quill. These lie between the basal parts of the 
tertiary fibers and enclose an angle with the secondary quill con- 
siderably more acute than the angle between the tertiaries and the 
secondary quill. They cross the direction of the latter at angles of 
20-25°. Ina line parallel to the secondary quill, which is the edge 
of the longitudinal ridge, these lines, which are the free margins of 
the secondary ridges described above, terminate suddenly (fig. 
20,1)’. 
If we combine the results of these observations we see that the 
basal parts of the tertiary fibers lie between the partitions like the 
bats of a stidiron, These bars arise from the inner face of a 
longitudinal ridge arising from the side of the secondary quill and 
extending obliquely upward. The bars decrease in height out- 
wardly and finally pass into the margin of the longitudinal ridge. 
The thickened ventral margins of the proximal portions of the ter- 
tiary fibers are enclosed between these bars; beyond the margin of 
the longitudinal ridge they are free. At the margin of the ridge 
a sharp bend occurs in the ventral margin of the tertiaries, its free 
outer portion enclosing a larger angle with the secondary quill than 
its proximal part. In the nearly symmetrical vanes of the distal 
remiges the secondary quills extend almost horizontally and, there- 
fore, the two vanes also are nearly horizontal. In the broad inner 
vane of the hand-remiges on the other hand, only the basal part of 
the secondary quills extends horizontally. Farther out they are at 
first bent a little downward but rise up toward their ends. The 
inner feather-vane therefore appears bent slightly in the form of 
an S, the hind margin of the feather being distinctly turned up. In 
the outer vane the secondary quills, which are here very short, are 
curved slightly downward. In the remiges of many birds of prey the 
inner vane suddenly becomes narrower in the upper third of its 
length. In this case the inner vane has a distinctly S-shaped curva- 
ture in its broad, proximal portion, the outer edge being much 
raised, while this curvature suddenly ceases where the broad, proxi- 
mal part passes into the narrow, distal part, the latter being like 
the front vane slightly bent downward. Since according to Ahlborn 
(1896, p. 18) the S-shaped curvature of the inner vane of the suc- 
ceeding remiges serves to insure a close overlapping of all parts 
