8 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
the whole literature on the subject. The works of Haecker (1890, 
pl. Iva, 1900, pl. x1v) contain some figures of transverse sections 
of secondary quills, which are not absolutely correct, but are essen- 
tially better and more true to nature than some others (e. g., Chad- 
bourne, 1897, pl. 1a). Unfortunately I was not able to see the 
treatise of Jeffries (1883) mentioned by Strong (1901, p. 160). 
Strong himself (1902, figs. 7, 8, 9, pl. 1) has published several good 
figures of transverse sections of secondary quills. Since, however, 
he made such sections of covert-feathers only, it is natural that the 
results I obtained deviate considerably from his. It seems that 
these formations are much more complicated in the remiges than in 
the covert feathers. According to my observations in the latter 
they have the following structure: Under the starting points of the 
tertiary fibers there arises from each side of the secondary quill a 
longitudinal ridge, not vertical but extending obliquely upward (figs. 
3, 4, G), which consists entirely of horn-substance. Its outer surface 
is smooth and continuous with the side of the secondary quill. Its 
inner side, which is turned toward the upper part of the secondary 
quill, is grooved, the grooves being separated by parallel secondary 
ridges (figs. 3, 4, L), which extend obliquely upward and outward. 
These ridges are highest at their origin and decrease in height dis- 
tally ; in the transverse section they appear like the teeth of a comb, 
and become shorter the further they are away from the secondary 
quill, the last being a slight prominence only. The ridges themselves 
are broadest at the base and grow thinner above. Their number in 
the sections varies from two to four and they may be more numerous 
in the secondary quills of larger feathers. In the small covert- 
feathers this main longitudinal ridge occurs, as has been described 
by Strong, but here the secondary ridges rising from its inner face 
are absent. The most difficult question to answer is, how the outer 
edge of the main ridge is formed. Without having reached a per- 
fectly satisfactory conclusion, I think I may pronounce it as probable 
that it is not smooth but interrupted by incisions lying between the 
ends of the secondary ridges. If this were not so, in a succession of 
transverse sectiows of secondary quills the secondary ridges would 
always terminate at exactly the same level, which, as serial sections 
show, is not the case. The level and the appearance of the edge of 
the ridge vary in every section, and on this fact the above supposi- 
tion is based. In the grooves between the successive secondary 
ridges lie the ventrally thickened margins of the proximal parts 
of the tertiary fibers. In sections one sees the first between the 
secondary quill and the first secondary ridge, and the second be- 
