A LABRADOR SPRING 
The group of river ducks, on the other hand, 
which includes the teals, mallard, black duck 
and wood duck, are not skilled in diving but 
obtain their food by dipping their heads and 
necks below the surface, while their tails point 
to the zenith in the ardour of the pursuit. 
These birds as well as geese and brant do, 
however, occasionally dive in an awkward 
manner, and in so doing use both feet and 
wings. 
The family of the loons and grebes is a curious 
one and its members are characterized by 
possessing very muscular legs, the thighs short 
and stout, the lower legs long and provided with 
keels for the attachment of powerful muscles. 
The grebes have also a very large knee-cap. 
In these respects the group resembles the fossil 
Hesperornis, a toothed bird with wings repre- 
sented by mere vestiges, but one that was 
evidently strongly specialized for propulsion 
through the water by means of the feet alone. 
Now loons and grebes are expert divers, and, 
although they occasionally have been seen to 
use the wings when hard pressed, as a rule they 
appear to swim, and that too very rapidly, 
under water with the feet alone. Young loons, 
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