1916] Chandler: Structure of Feathers 353 
In the Rallidae the down barbules are short, stout, and deeply 
pigmented, with short internodes. The pigment is present chiefly 
in the distal part of the internodes, the minute prongs and the 
proximal part of the internodes being more or less unpigmented. 
In Fallus obsoletus (pl. 36, fig. 107) the internodes reach a length 
of about 0.085 mm. In Gallinula the nodes are farther apart, 
while in Cresicus they are nearer together. In Psophia the down 
is black, as in Rallus, but the nodes are indistinct, and the pig- 
ment almost uniformly distributed. Huwrypya (pl. 36, fig. 106) has 
barbules which are more elongate and slender, very similar to that 
of the ardeid forms which have dark down, e. g., Botaurus (pl. 34, 
fig. 100). Aramus agrees with the cranes in the structure of its 
down, except that the barbules are not so slender. Cariama has 
down which is very long and filamentous, with enlarged nodes in 
all except the more basal barbules. In general the structure seems 
to be more like that of the Ardeae than like that of any other group. 
The down of Otis in the general form of the barb and vanules and 
length of barbules, is of galline type, but the minute structure is 
very different, the nodes being entirely undeveloped, and the bar- 
bules being merely long, slender, unmodified threads. 
d) Relationships 
As previously stated, the Gruiformes include a rather heterog- 
eneous assemblage of birds which show affinities to a number of 
other groups, but are so generalized in some respects and special- 
ized in others as to be very difficult to classify. The rails show a 
striking affinity, as far as their feather structure is concerned, to 
the Laro-limicolae. The cranes, on the other hand, differ from the 
Laro-limicolae, but agree with the Ciconiae, in the form of the 
proximal barbules of the outer vane of the remiges, which have 
no ventral cilia, while they agree with the Laro-lmicolae, but differ 
from the Ciconiae, in possessing flexules on the breast feathers. 
Aramus, in the structure of its breast feathers is more or less inter- 
mediate between the rails and the cranes, while in its back feathers 
it approaches the peristeropode Galli. Psophia also shows char- 
acters which are reminiscent of the megapodes and curassows, while 
Otis comes closer to the alectoropode type in the form of the bar- 
bules and barbicels. Hurypyga shows so many ardeid characters in 
the structure of its feathers that it strongly suggests its affiliation 
