362 NATATORES. 



is the web continued to the hind toe, and the general position 

 of the web being inwards rather than forwards, as may be 

 seen in the annexed figure of the right foot of the cormorant, 

 with the side outwards which is turned towards the centre of 

 the bird. 



If the prey is on the surface and small, these birds can 

 capture it by a snap of the bill, and ascend again without 

 losing the wing, in the same manner that the skimming 

 birds take the greater part of their food ; but, if the prey is 

 under the surface and larger, the wing must not only suspend 

 its action, but be considerably closed ; and the bird must 

 thus enter the water, using its wings as agents in again 

 ascending. In this operation, the head and gullet (the latter 

 often loaded with the prey) are thrown back by the flexure 

 of the neck, which is long and very elastic ; the feet are at 

 the same time brought forward till they are under the centre 

 of gravity, and by acting against the water, like two inverted 

 cups, jerk the body upward till the points of the wings clear 

 the surface, and the bird is on the wing in an instant. In 

 the gannet, which comes from the loftiest heights and with 

 by far the most velocity, the ascent is facilitated, the fall 

 broken, and indeed the plunge to so great a depth as the 

 rush of the descent would produce is prevented, by the pecu- 

 liarly buoyant structure of the bird. This buoyancy is pro- 

 duced by a quantity of air distributed in cells under the skin, 

 not exclusively for the purpose of respiration certainly, for 

 the gannet never has the head so long under water as to 

 require a reservoir of air for such a purpose. The descents of 

 the gannet from its greatest heights, (and as it descends 

 from these upon its prey, it has always the greatest initial, 

 and consequently by far the greatest final velocity,) head- 

 long as they are, and delivered upon the breast, very 

 differently from those of the osprey, would be sufficient to 

 stun the bird, and even to immerse it to a depth from which 



