1916] Chandler: Structure of Feathers 365 
Cuculidae in the structure of their feathers, although, as will be 
shown later, they have a peculiar pigmentation. 
The Psittaci differ from the Cueculi to a very slight degree. The 
barbules of the remiges, as exemplified by Cacatua galerita (pl. 30, 
figs. 74a-d), differ in no important details except the character 
of the proximal barbules of the distal part of the outer vane, 
where, instead of the pennulum being long with well-developed 
hooked cilia as in Coccyzus (pl. 30, fig. 72d), the base is shortened, 
the pennulum also short, and the ventral teeth somewhat increased 
in number, separated, and in the form of short, more or less tri- 
angular barbicels (pl. 30, fig. 74d). 
Melopsittacus differs in having distal barbules of the outer vane 
(pl. 30, fig. 75a) with rather stout bases and short pennula with 
crowded cells, the hooklets being long and closely approximated to 
one another and the ventral cilia also rather crowded. The proximal 
barbules undergo the same sort of modification on the outer part of 
the barb as in Cacatua (pl. 30, fig. 75d). 
The body feathers of the Psittaci resemble those of the Cuculi, 
but differ in that the barbicels are all less highly developed (pl. 30, 
figs. 76a, 77a, 77b). In breast feathers, frequently, practically 
all the barbicels are rudimentary or absent, except two or three 
rather conspicuous hooklets on the distal barbules (pl. 30, figs. 77a, 
77b). 
c) Down 
The down in Coccyzus, Cuculus, and Eudynamis resembles that 
of the typical Columbidae rather closely, but can readily be dis- 
tinguished. The barbules are long (2 mm. more or less) and very 
slender, and the nodes are in the form of round droplets some- 
what resembling the viscid droplets on a spider’s thread. Those 
near the base are large, while more distally they are very minute, 
but still maintain their globular form. In pigmented barbules 
the pigment is localized in a spot just back of the globular node. 
The internodes are exceedingly long and slender, in Hudynamis 
honorata sometimes 0.1 mm. long and less than 0.002 mm. in dia- 
meter. In Geococcyx the globular nodes are not in evidence, the 
cells being merely gradually enlarged, and pigmented on their distal 
half. 
The down of the Psittaci very closely resembles that of the typical 
euckoos, having more or less globular nodes which are rather large 
