292 iNTaoDUCTioK to zoology. 



fir plank about an inch and a-half thick, and which was used 

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

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

 neck. Pennant adds, that these bii'ds are sometimes taken at 

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

 to a floatmg 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 accui-ate 

 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 theu* haimts), 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 128 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 +he water, buo3'ant as the foam 

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

 swimming evmce its extreme hghtness ; its force of descent 

 no less establishes its possession of a certain degree of densit}"". 

 How are these opposite qualities united in the same individual? 

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

 facts which anatomists have made known from a careful exami- 

 nation 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 completely 

 filled, especially that which is situated in front of the merry- 

 thought. Further investigation showed that a free communi- 

 cation 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 communicating directly with 

 tbe lungs themselves. Numerous strips of muscular fibre 



* A fathom is six fi-et. Tbe facts are recorded by Mr. Wm. Thompson, 

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

 t Proceedings of Zoological Society, 1831. 



