170 THE STRUCTURE AND LIFE OF BIRDS cnap, 
with the relationship between families within the same 
class, but with the relationship between two classes. 
In the crocodile the muscle in question appears either 
not to connect with the toe-flexor muscles or else to 
be altogether functionless, for when I have bent the 
ankle-joint of a young American alligator, most pro- 
bably resembling a crocodile in this point of anatomy, 
no effect at all has been produced upon the toes. 
The habit of standing on one leg is common to 
many birds. The Heron is well known for it. 
“ Nigh upon that hour 
When the lone hern forgets his melancholy, 
Lets down his other leg and, stretching, dreams 
Of goodly supper in the distant pool.” 
Flamingoes, Storks, and Cranes can frequently be 
seen in this posture at the Zoological Gardens. 
It is said to be a restful one, and it must have 
merits or they would not adopt it. But if the leg be 
watched it will be seen to be perpetually swaying to 
and fro. In fact the balance is only maintained by 
the help of perpetual small muscular adjustments, of 
which, no doubt, the bird is capable while asleep, 
some lower part of the brain working when the cere- 
bral hemispheres, the seat of conscious life, are at. 
rest. 
Swimming. 
People maintain that they have seen from a boat a 
Shag “flying under water,’ swimming, that is, by 
means of his wings. Among the diving birds at the 
Zoological Gardens there is frequently a Shag, and as 
