XVI HISTORY OF THE OSTRICH 393 
(4) Rudimentary hooklets or barbicels have been 
found in the wing-feathers of the Rhea and some of the 
allied birds. This is a most important fact. If they 
did not help in flight, by making the feathers im- 
pervious to air, it is difficult to imagine what purpose 
they can have served. 
(5) The fusion of the hand-bones in the Ostrich 
shows that the wing-feathers were once stronger and 
that the wing had work to do. 
(6) Definite apteria have been found in some birds 
of the Ostrich kind. Even if this were not the case, we 
might urge that the point is one of little importance, 
since the Penguin has none. 
On the whole the arguments seem to show that the 
progenitors of the Ostrich were birds of flight. But 
the question is a difficult one. 
1 The whole question is discussed in Fiirbringer’s Ustersuch- 
ungen zur Morphologie und Systematik der Vogel, p. 1481. See 
also Bronn’s 7hder-Reich, vol. “ Aves.” 
