NATATORES. 429 



elevates itself in the air, rising and falling as if some concealed 

 power guided its various motions, without any muscular 

 exertion of its own, and then descending sweeps the air close 

 to the stern of the ship with an independence of manner as if 

 it were ' monarch of all it survey 'd.' It is from the very little 

 muscular exertion used by these birds that they are capable 



of sustaining such long flights without repose When 



seizing an object floating on the water they gradually descend 

 with expanded or upraised wings, or sometimes alight and 

 float like a Duck on the water, while devouring their food ; 

 then, elevating themselves, they skim the surface with ex- 

 panded wings, giving frequent impulses as they run along for 

 some distance, until they again soar in mid-air and recommence 

 their erratic flights." 



Like the other species of the genus, it is nocturnal as well 

 as diurnal, and no bird with which I am acquainted takes so 

 little repose ; it appears to be perpetually on the wing, 

 scanning the surface of the ocean for mollusks and medusae, 

 and the other marine animals that constitute its food. So 

 frequently does the boldness of this species cost it its life, 

 that hundreds are annually killed without, however, its num- 

 bers being apparently in any degree lessened; it readily 

 seizes a hook baited with fat of any kind, and if a boat be 

 lowered its attention is immediately attracted, and while 

 flying round it is easily shot. Many exaggerated and mar- 

 vellous accounts having been published respecting the weight 

 and the dimensions of this bird, particularly of the extent 

 from tip to tip of the wings, I paid much attention to the 

 subject, and, after killing numerous examples of both sexes 

 and of all ages, I found the average weight of the Diomedea 

 cxularis to be seventeen pounds, and the extent from tip to 

 tip of the wing ten feet one inch. Dr. McCormick, R.N., 

 however, informs me that he has met with examples weighing 

 as much as twenty pounds, the extent of whose outstretched 

 wings measui'ed twelve feet. The known breeding-places of 



