Music and Dancing tn Nature. 265 
the Chinchillidze family, have greatly developed 
vocal organs, and resemble birds in loquacity; but 
mammals generally, compared with birds, are slow 
and heavy, and not so readily moved to exhibitions 
of the kind I am discussing. 
The terrestrial dances, often very elaborate, of 
heavy birds, like those of the gallinaceous kind, are 
represented in the more volatile species by per- 
formances in the air, and these are very much more 
beautiful ; while a very large number of birds— 
hawks, vultures, swifts, swallows, nightjars, storks, 
ibises, spoonbills, and gulls—circle about in the 
air, singly or in flocks. Sometimes, in serene 
weather, they rise to a vast altitude, and float about 
in one spot for an hour or longer at a stretch, 
showing a faint bird-cloud in the blue, that does 
not change its form, nor grow lighter and denser 
like a flock of starlings; but in the seeming con- 
fusion there is perfect order, and amidst many 
hundreds each swift- or slow-gliding figure keeps 
its proper distance with such exactitude that no 
two ever touch, even with the extremity of the long 
wings, flapping or motionless :—such a multitude, 
and such miraculous precision in the endless curving 
motions of all the members of it, that the spectator 
can lie for an hour on his back without weariness 
watching this mystic cloud-dance in the empyrean. 
The black-faced ibis of Patagonia, a bird nearly 
as large as a turkey, indulges in a curious mad 
performance, usually in the evening when feeding- 
time is over. ‘T'he birds of a flock, while winging 
their way to the roosting-place, all at once seem 
possessed with frenzy, simultaneously dashing 
