THE CONQUEST OF THE DRY LAND 207 
does the crab on the shore lever itself along; 
so do we when we walk. This is the punting 
method. (3) He may take an oar, and, going 
to the stern of the boat, he may press the water 
from side to side, displacing masses of water 
in a regular rhythm. So does the fish grip the 
water with the posterior part of its body, popu- 
larly called the tail, and thrust the water away 
from it, first to one side and then to the other. 
So does the whale with its propeller-like tail 
—a propeller, however, that does not go round. 
This is the scul/ing method. (4) Or the man 
may sit down on the seat of the boat and take 
up the oars and row. The insect called the 
Water-Boatman rows on the water with its third 
pair of legs; the turtle rows with its flipper- 
like limbs, and the penguin with its flightless 
wings and with its feet as well. Aquatic birds, 
when swimming, row with their feet; some 
diving birds row under water with their wings. 
Flying birds row in the air with their wings. 
Now it may be said that the conquest of the 
dry land meant, among other things, that the 
punting kind of locomotion became very im- 
portant. It was learned on the shore; it was 
perfected on dry land. Even the snake, which 
