308 INTRODUCTION TO ZOOLOGY. 



in the curing of tlic fish, and darted down with such violence 

 that it struck its bill quite through the hoard, and broke its 

 neck. Pennant adds, that these birds are sometimes taken 

 at sea by a similar deception, a fish being fastened for the 

 purpose to a floating plank. 



But perhaps a juster estimate of the impetus of the descent 

 may be formed from the depth to which it propels the bird in 

 the water. Respecting this we possess the means of accurate 

 information; for Gannets are not unfrequently found entangled 

 in fishing-nets, and the depth at which these nets are fixed is 

 ascertained. Thus, at Ballintrae, on the west coast of Scot- 

 land," and not remote from the Craig of Ailsa (which has been 

 mentioned as one of their haunts), the Gannets are not un- 

 frequently taken in nets sunk to the depth of from nine to 

 twenty fathoms, and sometimes to that of thirty fathoms.* 

 On one occasion, so many as 1 28 of these birds were thus 

 captured at one time, and in their struggles brought the nets 

 with their sinkers and fish to the surface. 



The Gannet swims high in the water, buoyant as the foam 

 which crests the wave on which it rides. Its flight and its 

 swimming evince its extreme lightness; its force of descent 

 no less establishes its possession of a certain degree of density. 

 How are these opposite qualities united in the same individual? 

 On this point we are not left to conjectures, but can appeal 

 to facts which anatomists have made known from a careful 

 examination of its structure. Thus, a Gannet which died in 

 the Zoological Gardens of London, was examined by Professor 

 Owen,t chiefly with reference to the air-cells, which, in this 

 bird, as in the Pelican, have a most extensive distribution. 

 By means of a gentle but continued inflation through the 

 wind-pipe, the integuments of the whole of the lateral and 

 inferior parts of the body rose, and the air-cells seemed com- 

 pletely filled, especially that which is situated in front of the 

 merry-thought. Further investigation showed that a free 

 communication existed among these, with the exception of 

 that in front of the breast. This cell was found to be of a 

 globular form, about four inches in diameter, and communi- 

 cating directly with the lungs themselves. Numerous strips 

 of muscular fibre passed from various parts of the surface of 



* A fathom is six feet. The facts are recorded by Mr. Win. Thompson, 

 Magazine of Natural History, vol. ii. No. 13. 

 f Proceedings of Zoological Society, 1831. 



