WINGS AND FEET 
bodies has been exhaustively studied by naval 
architects, and it has been shown that a prop- 
erly shaped body completely submerged under 
ideal circumstances with the wave eliminated 
meets with little resistance besides friction. 
The fact that a loon when swimming rapidly 
on the surface is apt to depress its body in the 
water so that its back is awash seems to favour 
this contention. It may be argued that the 
bird does this to avoid observation or to escape 
being shot, but it certainly swims faster when 
thus submerged. Under water the diving bird 
has a great advantage in being able to assume 
a shape best adapted to cleaving the liquid 
medium. 
Incidentally it may be remarked that the 
loon, in perfecting its legs for use under water, 
has disabled itself for walking on the land, 
but as it usually builds its nest on or close to 
the water, it can well afford to sacrifice ter- 
restrial locomotion. 
The combined use of wings and feet, a 
reptilian form of progression, would naturally 
be found among birds that had not fully 
specialized in either direction. Among living 
birds the cormorant and the penguin represent 
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