NINTH ANNUAL REPORT. 
1 
Oo 
— 
OSTRICH. CONDOR. CONDOR. EMEU. 
COMPARISON OF THE FEATHERS OF THE OSTRICH, CONDOR, AND 
EMEU 
were not absolutely necessary. Hence the extreme degeneration 
of remiges in these birds. 
The wide web of skin filling up the angle between the humerus 
and the body, in the wing of the Ostrich, is interesting as being 
perhaps a vestige of some old-fashioned patagium, functional in 
primitive ancestors. 
C. Rectrices——A rudder is as useless to a bird which has lost 
the power of flight as the fin of a tadpole would be to an adult 
frog. Thus rectrices are entirely lacking in the Rhea, Cassowary, 
Emeu and Apteryx. In the Ostrich, there are many long, loose- 
vaned, curling plumes representing these feathers. 
D. Body Feathers——These have followed three general types 
in their degeneration, or perhaps we should say that their present 
condition represents three more or less homologous stages. 
These are excellently represented in the photograph, and for com- 
parison I have chosen a secondary from the wing of a condor. 
As an example of the type showing least degeneration may be 
taken the feathers of the Ostrich and Rhea. In a typical feather 
