PROCELLARIIOE PBION 489 



Description. Adult. Above pale ashy-blue, darker on _ the 

 crown, nape, lesser wing-coverts, outer webs of the outer primaries 

 and scapulars, the last tipped with white ; feathers of the middle 

 of the forehead and anterior part of the crown largely tipped with 

 white ; rest of the forehead and whole of the under surface pure 

 white ; sides of the breast ashy-blue; under wing coverts, primaries 

 beneath, and axillaries white ; outer tail-feathers white, the next 

 two ashy, with the base of the inner web white, the three next ashy 

 with white tips, widest on the middle feather, a slightly darker 

 subterminal ashy band. Bill black ; edge of the mandible blue ; 

 tarsi and toes blue ; webs flesh colour. 



Length about 11-0; wing 8*5; tail 3'6 ; bill 1-4; tarsus 1'3; 

 middle toe 1*6. 



Distribution. The Blue Petrel is found throughout the Southern 

 Ocean, usually between lat. 40 and 60 S., though occasionally 

 wandering beyond those limits. It appears to be a somewhat rare 

 bird in the seas immediately surrounding the coasts of South Africa, 

 though occasionally driven northwards by gales. An instance of 

 this occurred to Mr. Eickard at East London. Professor Van- 

 hoffen identified a considerable number of these birds at sea two 

 days out from Cape Town towards the Bouvet Islands, in about 

 40 S., lat., 15 E. long. 



Habits. There is but little of special interest in regard to the 

 habits of the Blue Petrel. Kidder and Eaton both found it breeding 

 on Kerguelen ; a single egg is laid at the end of a long and some- 

 what tortuous burrow placed in the hill-side near the sea. The 

 birds can be easily traced by the curious dove-like coo, to which 

 they give vent from their burrows when any one approaches. The 

 egg is ovoid and dull white in colour, measuring about 2 f O x 1'5. 





798. Prion banksi. Banks' Blue Petrel. 



A 



Pachyptila banksi, Smith, III. Zool. S. Afr. Aves, pi. 55 (1840). 

 Prion banksi, Gurney, Ibis, 1864, p. 355 [Natal Coast] ; Layard, B. S. 

 Afr. p. 362 (1867) ; id. Ibis, 1867, p. 460 ; Sperling, Ibis, 1868, p. 293 ; 

 Salvin, Cat. B. M. xxv, p. 434 (1896); Shelley, B. Afr. i, p. 168 

 (1896) ; Reichenow, Vog. Afr. i, p. 32 (1900) ; Shortridge, Ibis, 1904, 

 p. 204. 

 Prion vittatus, Sharpe, Phil. Trans, vol. 168, p. 135, pi. vii, fig. 7 



(1879) ; id. ed. Layard's B. S. Afr. p. 769 (1884). 

 Description. Adult. General colour above ashy-blue, darker on 

 the head, nape, and on a streak below and behind the eye, above 



