COMMON GANNET. 419 



inflation to communicate witli the cavity of the body and 

 the trachea. Montaj^u imagines this singiihir conformation 

 in the Gannet to be intended chiefly for the retention of 

 heat, as well as to give lightness and buoyancy to the bird, 

 and thereby enable it to exist in the midst of tempests, far 

 from land, where it is necessary for it to remain, while in 

 pursuit of its food. It appears, however, much more pro- 

 bable that the singular anatomy of the Gannet is connected 

 with its mode of plunging after its prey. 



In dissecting- a male bird of the same species from Boston, 

 Massachusetts, I observed, among many other details, some 

 of which are related in the fourth volume of Mr. Audubon's 

 work, the peculiarities above alluded to. " The cellular 

 tissue of the back exhibits vacuities of very large size, inter- 

 vening between the skin and the muscles : one, at the lower 

 part of the neck behind, being 5 inches in length ; another 

 5^ inches long, extending from the furcula down the humerus ; 

 and behind the wings four others, extending to the last rib. 

 Branches from these pass between the muscles, w-hich present 

 the appearance of having been, as it were, dissected. A cell 

 of enormous size covers the side of the abdomen, and another 

 pair run down the middle of it, separated by a partition in 

 the median line. That part of the cellular tissue which 

 adheres to the bases of the feathers is also remarkably loose ; 

 and close to each of them is a roundish aperture of large size, 

 communicating with the great cavities mentioned above. 

 Between the pectoralis major and the subjacent muscles is a 

 large interspace, formed by a great cell. The internal tho- 

 racic and abdominal cells are also very large." 



American specimens have been compared by me with 

 Scottish, both by inspection of the exterior and by dissection, 

 and I have no doubt as to their being of the same species. 

 Mr. Audubon found it breeding on a rock in the Gulf of St. 

 Lawrence, and frequently saw it on the Gulf of Mexico in 

 winter. 



I have still to say a few words respecting a Black-tailed 

 Gannet. 



Whether Mr. Gould's Sula melcmura be a good species, 

 or whether the specimen to which I allude belong to it, I 



