772 The American Naturalist. 
[September, 
the earlier down papilla except that it is seated in a follicle. 
There now occurs the same outgrowth of ridges from the 
pulp as before, divid- 
ing the epidermis in 
a similar manner, 
with the following 
exceptions: In the 
down papilla these 
ridges were parallel 
to the axis of the 
future feather; in the 
contour feather (fig. 
Fic. 8.—Longitudinal 9) they are oblique to 
sectionthroughtheshaft that axis, the result 
0 0 zi á . 
feather, after Davies, necessarily bein 
that the formations 
ff, feather follicle; pi, of a series of long 
mer 
definitive feather germ; 
pith; q, quill. slender processes— 
the future barbs—which are connected 
with an undivided portion, the shaft— 
on the so-called dorsal side of the papilla. 
Around all is developed a sheath as 
before. 
This dorsal or shaft region demands a 
little closer attention. As seen in trans- 
verse section (fig. 10) the shaft shows on 
its inner edges longitudinal thickenings 
which, increasing in size, meet each 
other in differing ways in the different 
parts of the feather. A glance at figure matic 
11 will explain this better than pages of 
description. The four sections are made 
at different levels, A being near the tip 
and D through the quill below the vane. 
Around each is the feather sheath and 
inside of each is the pulp cavity. In A the ingrowing edges 
of the shaft meet each other, and form a solid rod. Farther 
down, as in B and C, they include in the ingrowth a portion 
