and with a kick up, as it were, of the legs and tail. If one sits on a height and they come sufficiently near inshore to look down on them at an acute angle, one can follow their course under the water, often for a considerable time. One remarks then that the wings are moved both together—flapped or beaten—so that the bird really flies through the water. In flight, however, they are spread straight out without a bend in them, whereas here they are all the while flexed at the joint, being raised from and brought downwards again towards the sides in the same position in which they repose against them when closed. These birds—and, no doubt, the other divers—dive not only to catch fish, but also for the sake of speed. I have seen them when travelling steadily along the shore duck down and swim or fly like this, in a straight line and but just below the surface of the water, always pursuing the same direction, and seeming to have no difficulty in guiding themselves. The speed was very much greater than when they merely paddled on the surface. Thus we may see, perhaps, how such birds as the great auk and the penguins came to lose the power of flight. They could fly in two ways, either through the air or the water. The first—as long as they retained it at all, probably—was much the quicker; but the other was quick enough for their purposes, and the effort required to rise from the water was thus dispensed with. These razorbills dived in order to get more quickly to some point for which they were making. They might have got there still sooner by flying, but the time saved was evidently not worth that effort to them. But the power of flight might be long retained by a bird—though useless to it
