166 Proceedings of the Royal Physical Society. 



is pure white, except (1) a few creamy feathers, with irregular 

 bars of pale greyish-brown, on the scapulars ; (2) that the 

 lower breast and abdomen are washed with pale umber, the 

 feathers of the latter being edged with white, producing a 

 mottled appearance ; and (3) that the under tail-coverts are 

 barred with pale'umber. Indeed, so white is this example, 

 that, when viewed from the distance of a few feet only, 

 the vestiges of its previous garb are not apparent. The 

 apical third of the bill is blackish, as in the previous 

 stages. 



At the subsequent moult, or during the fourth year, the 

 bird arrives at maturity. A pearl-grey mantle is assumed ; 

 the secondaries are tipped with white, forming a band that 

 contrasts with the grey ; the bill becomes yellow, with a red 

 patch at the angle of the lower mandible ; the rest of the 

 plumage pure white, except in winter, when the head and 

 neck, as in other members of its genus, become streaked and 

 mottled with pale brown. 



In this Orcadian specimen the wing measures 15 inches, 

 the culmen 1*62 inch, and the tarsus 2*07 inches. 



That examples in the white stage of plumage have remained 

 so long unknown may probably be explained by the following 

 facts : — {First) Because this phase of plumage is only worn 

 for a few months during the third year of the bird's existence. 

 {Second) The species is far from abundant. This is due in 

 some measure, perhaps, to its habitat being remarkably 

 circumscribed, since the bird is confined in summer to the 

 island of Jan Mayen, Greenland, and, possibly, the American 

 side of Baffin's Bay. {Third) Because the older individuals, 

 including the white birds, do not, as a rule, wander far from 

 their Arctic haunts, their regular winter range extending to 

 Iceland, the Faroes, and Scandinavia. It is almost entirely 

 the young birds that roam irregularly to the British seas, 

 and on rare occasions as far as the Bay of Biscay, and 

 on the American side of the Atlantic to the coast of 

 Massachusetts. 



When speaking on this species before the Eoyal Physical 

 Society, it is interesting to recall the fact that on the 8th 

 of March 1823, Mr Laurence Edmonston communicated to 



