VII FLIGHT 253 
held it in position, lets it hang almost vertically down- 
wards. The wings are held extended, with just a slight 
bend at the wrist, facing forwards, and so putting the 
break on as strongly as possible. The tail forms the 
largest fan it can spread to. For.stopping it is perhaps 
more important than for steering. If the Pigeon be 
watched from underneath, another very curious point 
may be made out. It will be seen that the bastard 
wings are called into play to add to the spread of canvas. 
They are often spoken of as quite rudimentary, or as 
useful only in strengthening the wing, though how they 
can act in this way is difficult to see. One ornithologist 
imagines that in making a turn a bird extends one 
bastard wing and revolves round it as on apivot! I had 
long wondered what their use could be or how so many 
muscles could be wasted on a mere rudiment, when I 
saw a Pigeon, when checking his speed in order to 
settle, lift the bastard wing so that daylight was visible 
between it and the long feathers, this petty appendage 
jutting out, and impudently spoiling the beautiful line 
of the front margin of the wing from shoulder to tip. 
If you stand at the entrance to the British Museum 
(the Antiquarian Department at Bloomsbury) this 
curious phenomenon may easily be seen, as the Pigeons 
which are usually feeding in large numbers on the 
gravel in front fly up and settle overhead on the 
pediment. In two specimens of Kestrel Hawks which 
I have examined, the extension of the wing necessarily 
extended the bastard wing, the tendon within the 
anterior membrane attaching not only to the metacarp 
but alsotothe thumb. The purpose of this is not clear, 
nor have I noticed anything of the kind in other birds, 
