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36 ON THE CLASSIFICATION OF BIRDS. 
and compressed on the sides—and the mouth destitute 
of stiff bristles; but, what is more singular, the rump 
feathers in both are of precisely the same construction. 
It will be remembered that these, in the caterpillar- 
catchers, are particularly thick set, and that,when pressed 
against by the hand, a sensation is given of being : 
pricked, just as if the shafts of the feathers beneath the 
surface terminated in little sharp points. This suppo- — 
sition, although it has been urged as a fact by Cuvier, is 
entirely erroneous. ‘These feathers have the shafts very 
thick at the base, but towards the middle they suddenly 
become very slender: by being pressed against they bend 
into a sharp angle, the thicker part of the shafts resisting, 
and the thinner yielding to the pressure; the angle thus 
formed, is, in fact, the prickle which all ornithologists 
have believed in. Now, although the rump feathers of the 
orioles do not possess this property in the same degree, 
the shaft is formed on the same principle: it is thick at 
the base, but suddenly becomes very fine ; and if gently 
pressed, the hand feels a prickly resistance: the same 
character belongs to the beautiful I7vena Puella, a bird 
classed by the Linnean naturalists with the rollers, and 
by some of the moderns with the drongo shrikes. 
Dr. Horsfield, therefore, is perfectly correct in assimi- 
lating it to this group. The last analogy is that between 
the tyrant shrikes (Tyrannine) and the long-legged 
thrushes (Crateropodine), which are thus brought into 
contact. As these two groups are the most remote, and 
both pass into different families, so their resemblance is 
more distant. Yet there are not wanting certain charac. 
ters which they possess in common: the breadth of the 
tailis peculiarly conspicuous in both ; the bristles round 
the mouth of the long-legged thrushes are more developed 
than in any other group of the family ; another charac- 
ter which is common to the tyrants. It has been men- 
tioned by Wilson, and we can confirm the fact from 
personal experience, that most of the tyrant fly-catchers 
constantly resort to the vicinity of water, into which they 
frequently dive. Now, this fact explains at once the 
Saas 
