NATATOllES. 451 



brown ; back, wing-coverts, and upper tail-coverts slate-grey, 

 each feather margined with dark brown ; face and all the 

 under surface brown, washed with grey on the abdomen ; 

 bill, tarsi, toes, and membranes black. 



Total length 16 inches ; bill 1 j ; wing 12 ; tail 5^ j tarsi f ; 

 middle toe and nail 2f . 



Genus ^ESTRELATA, Bonaparte. 



The members of this well-marked genus, as might be ex- 

 pected from the length of their wings, have great powers of 

 flight. In the delicate form and colour of their feet and legs 

 they differ very considerably from the PterodromcB. One 

 species — JEstrelata hasitata {Procellaria hasitata, Temm.) — 

 has been killed in England. 



Sp. 630. ^STRELATA LEUCOCEPHALA. 



White-headed Petrel. 



Procellaria leucocephala, Forst. Drawings, No. 98. 



lessonii, Garn. Ann. des Sci. Nat,, torn. vii. t. 4. 



vagahunda, Sol. MSS. 



JEstrelata leucocephala, Bouap. Consp. Gen. Av., torn. ii. p. 189, 



^strelata, sp. 4. 

 Rhantistes lessoni, Bonap. Compt. Rend, de PAcad. Sci., 1856. 



Procellaria lessonii, Gould, Birds of Australia, fol., vol. vii. pi. 49. 



While engaged in watching the movements of the several 

 species of the great family of Frocellaridcs, which at one time 

 often and often surrounded the ships that conveyed me round 

 the world, a bright speck would appear on the distant 

 horizon, and, gradually approaching nearer and nearer, at 

 length assumed the form of the White-headed Petrel, whose 

 wing-powers far exceed those of any of its congeners; at 

 one moment it would be rising high in the air, at the next 

 sweeping comet-like through the flocks flying around ; never, 



2 G 2 



