1916] Chandler: Structure of Feathers 309 
cilia, subequal in size. On more distal portion of barbs, sharp 
distinction between base and pennulum is lost, the barbules becom- 
ing very narrow and simple, with a few weak, curved ventral cilia 
near tip. Proximal barbules very much like those of back, but 
more simple, and on terminal portion of barbs assuming a form very 
similar to distals opposite them, except that the ventral barbicels are 
longer and more numerous. 
b) Other Types 
(1) Plotinae 
Plotus, although grouped with the Phalacocoracidae, constituting 
the subfamily Plotinae, differs from Phalacocorax so widely in its 
feather structure that on this basis alone it should be entitled to 
full family rank. The Steganopodes as a group are characterized 
by the unusual difference in the different families as regards their 
minute feather structure, but no two families of the order are more 
distinct from each other than is Plotus from Phalacocoraz. 
Taking Plotus anhinga as a type, we find that the distal bar- 
bules of the inner vanes of the remiges (pl. 18, fig. 18a) are remark- 
ably reminiscent of those of the Cathartidae. The bases are elongate 
and narrow, about 0.35 by 0.03 mm., while the pennula are about 
0.45 mm. long. The twist between the base and pennulum is of 
such a nature as to give the dorsal contour a peculiar, characteristic 
wavy curve. When spread back between thumb and forefinger 
both the base and the tip of the pennulum lie in a vertical plane, 
only the moderately broad hooklet area lying on its side, giving it 
a hump-backed appearance. The ventral teeth are lobate, and pro- 
ject straight forward in a direct line with the ventral edge of the 
base. The hooklets, usually five in number, are relatively short 
and stout, but progressively increasing in length; the ventral cilia 
are coarse, straight, and blunt, all but the proximal one or two 
being closely appressed to the barbules. All of the dorsal barbules 
are absent entirely, except the specialized one or two basal ones, 
which have the form of stout, blunt, forward and laterally project- 
ing spines. Immediately distal to them the dorsal contour of the 
barbule curves evenly downward. The proximal barbules (pl. 18, 
fig. 13b) are hardly less peculiar. In these the base is short and 
stout, hardly longer than the base of the distals, and about 0.55 
wide, with very short, triangular ventral teeth. The pennulum is 
remarkably short and stout, beimg considerably shorter than the 
abbreviated base, and 0.02 mm. wide, the cells of the ventral tooth 
region and beyond having conspicuous, recurved dorsal spines, and 
