292 University of California Publications in Zoology Vou. 13 
forming compact, well-developed vanes, the result being that the 
plumage of these birds is much coarser and more bristly than that 
of emus. 
The feathers have a somewhat different general shape. While 
in emus they are elongate and narrow with approximately a uniform 
width throughout, in cassowaries their widest point is a few centi- 
meters above the umbilicus, thence more or less gradually tapering 
to the tip. The aftershaft is as highly developed as in emus, and 
as with the latter resembles the main feather plate in structure as 
well as size. The calamus is exceedingly short, shorter in Casuarius 
uniappendiculatus than in C. papuanus; in fact, it is so short in the 
former that the division into shaft and aftershaft occurs under 
the surface of the skin, the feather thus appearing completely 
double. The barbs are moderately developed, not sword-shaped, 
and spaced about 7 or 8 per centimeter, increasing to 16 per centi- 
meter at the base; the barbules (pl. 14, figs. 3a, 3b) are of about 
the same length as in Dromaeus (1 to 1.8 mm.) but entirely lack 
the prongs at the nodes, the latter being indistinguishable, and the 
pennula simple threads. The naked terminal portion of the 
feather, which sometimes constitutes three-fourths of the entire 
feather, and reaches a length of over 20 cm., sometimes has the stiff, 
bristle-like naked barbs present in decreasing numbers all the way to 
the tip, where there are only two or three per centimeter on each side, 
while in other cases, especially in shorter feathers, the naked shaft 
is produced as a very coarse, stiff bristle. 
c) Relationships 
While agreeing with the ostriches and rheas in characters 
common to all the Ratitae, the cassowaries and emus differ from 
either of the former types far more than they differ from each other. 
The present group, with the Apterygiformes, on the one hand forms 
a subdivision of the Ratitae comparable with the Struthioniformes 
and Rheiformes on the other, though the latter are more nearly 
related to each other than are the former. The enormous after- 
shaft, the few reduced remiges, the coarse texture of the plumage, 
and the form of the barbules, are all striking points of difference 
from the ostriches and rheas, while in all except the aftershaft 
they agree more closely with the Apterygiformes in these characters. 
Although in their feather structure there is no positive evidence 
of their being primitively rather than secondarily flightless, there 
