PETRELS. 



525 



on the water in great composure in the most tremendous seas ; but it is observed 

 that in heavy gales they fly extremely low, generally skimming along by the 

 surface of the water. They are extremely greedy of the fat of the whale, and 

 though few should be seen when a whale is about being captured, yet, as soon as 

 the flensing process commences, they rush in from all quarters, and frequently 

 accumulate to many thousands. They then occupy the greasy track of the ship ; 

 and being audaciously greedy, fearlessly advance within a few yards of the men 



FULMAR PETRELS (J nat. size). 



employed in cutting up the whale." Highly gregarious during the breeding-season, 

 the fulmars then collect on the turfy ledges of the St. Kilda cliffs in thousands. 

 The single white egg is laid either in a slight nest of dried grass, or on the bare 

 ground ; and although the birds sometimes excavate a hollow of a few inches deep 

 in the turf, they as often nest on its surface. 



Nearly allied to the fulmar is the silver-grey petrel (Thalassoica 

 glacialoides) of the Pacific and Southern Atlantic, distinguished by 

 its more slender beak, in which the nasal tubes are shorter and more depressed, with 

 their upper border concave. This species extends nearly as far south as the 

 Antarctic pack-ice, where it is replaced by the snowy petrel (Pagodroma nivea), a 



Allied Genera. 



