1916] Chandler: Structure of Feathers 299 
tional remiges, although the birds are adapted for aquatic life. 
They also possess typically developed pennaceous barbules. The 
aftershaft is present with a short weak shaft, and numerous 
spreading barbs. 
a) Gavia immer 
(1) Remez 
Development very high, totally different from primitive condi- 
tion in penguins. Shaft slightly broader than deep, distinctly 
quadrangular, with narrow median groove on ventral side and 
barbs attached nearer dorsal surface, as in all other flight birds. Rami 
of both vanes, though narrow at junction with shaft, immediately 
become very wide, with a broad, membranous ventral ridge, the 
total width of ramus then equivalent to that of shaft, i. e., about 1.6 
mm., the translucent ventral ridge constituting approximately one- 
fourth the width of the ramus. Rami taper rapidly and become narrow. 
Lower edge of ventral ridge almost if not quite smooth, no villi pro- 
jecting ventrally. About 20 barbules per centimeter, usually a few 
less on outer vane, a few more on inner. 
Inner vane.—Distal barbules (pl. 16, fig. 8a) characterized by a 
broad, well-formed base about 0.27 mm. long, narrowing proximal 
to ventral teeth; latter 1 or 2, narrow and fingerlike; pennulum 
moderately long; hooklets 4 or 5, moderately long and slender, well- 
formed; ventral cilia moderate, straight, more or less appressed to 
shaft; basal two or three dorsal cilia stout and triangular, the 
transition to rudimentary distal ones gradual. Total length of 
barbule about 0.6 mm. Proximal barbules (pl. 16, fig. 8b) rather 
stout, about 0.483 mm. long by 0.05 mm. wide, with about 4 long, 
slender, conspicuous ventral teeth; pennulum filamentous, with 
rudimentary barbicels. 
Outer vane—Distal barbules (pl. 16, fig. 8c) with elongated 
base (0.33 mm. by 0.033 mm.) with 2 rather small ventral teeth. 
Hooklet region of pennulum very broad (pl. 16, fig. 8c, this barbule 
being twisted to show this characteristic). Hooklets considerably 
increased in number, 6 or 7 present; ventral cilia very much as in 
inner vane, and dorsal cilia absent entirely. Towards inner part of 
barbs, bases of barbules much shorter and hooklets gradually chang- 
ing over to curved ventral cilia, strongly hooked, reminiscent of 
those in penguins. Proximal barbules of distal part of outer vane 
(pl. 16, fig. 8d) with considerably narrower bases than those of inner 
vane, and pennulum with a complete series of ventral cilia, the more 
proximal ones strongly curved and hooked. The more basal proxi- 
mal barbules very similar to those of inner vane, the ventral teeth 
elongating on more distal barbules, ultimately forming the 4 or 5 
proximal hooklike ventral barbicels, the more proximal cells of pen- 
nulum adding more barbicels to these until a complete series is 
formed. 
(2) Other Feathers 
Back feathers with well-developed interlocking vanules basally. 
Distal barbules with both base and pennulum elongated, the former 
