SHEATH-BILLS— ANTARCTIC SKUA — ALBATROSES 315 



it invariably walks from left to right. In colour the wry-bill is grey, with white 



under-parts, and a black collar, broader on the left than on the right side, round 



the neck. Although bilateral asymmetry is extremely rare among vertebrated 



animals, it occurs in the skulls of dolphins and all the other cetaceans furnished 



with teeth, in the internal ear of certain owls, and, most markedly, in the male 



narwhal of the Arctic, which normally has but one properly developed tusk. 



Intermediate in certain respects between the plover and the gull 



tribes are the exclusively Antarctic birds known as sheath-bills, or 



kelp-pigeons, one of which (Chionis alba) was discovered by Captain Cook on New 



Year Island, and has been subsequently observed on many other islands to the 



south of the Strait of Magellan, while the second species, C. minor, the lesser 



sheath -bill, inhabits the Crozets and Kerguelen Island. In appearance these 



sheath-bills resemble white pigeons ; the beak in the larger species being yellow 



and pink, with the sheath flattened, while in the smaller kind it is black with the 



sheath curved. On Kerguelen, where they abound, these birds feed chiefly on 



penguin eggs; but they also consume carrion and vegetable substances. They 



lay, in a rude nest of grass placed among rocks, two large, dull, greyish blue eggs 



spotted with dark reddish brown and violet, from which in due course are hatched 



the wholly black chicks. 



The Antarctic skua, or sea-hen (Megalestris antarctica), which 

 Antarctic Sfccuii. 



equals the great skua of northern Europe in point of size, and also 



resembles that bird in its predatory mode of life, is sooty brown in colour, both 



above and beneath. 



Largest of all sea-birds is the wandering albatros (Diomedia 

 Albatroses. = . . , , & 



exukms), m which the expanse 01 wing reaches to as much as 

 10 feet, although the weight of the whole bird may not exceed 17 lb. This 

 magnificent species — of which the plumage is pure creamy white with black wings 

 — seldom ranges much to the north of 35° S. latitude, and breeds on the Auckland 

 and other islands in the far south. The smaller black-eyed albatros (D. melanophrys), 

 characterised by the presence of a black band on each side of the eye, as well as by 

 the dark grey wings and paler grey tail, is, however, the species to which the epithet 

 " wandering " is really more appropriate, since it may frequently be seen so far 

 north of the equator as California, and may even occasionally straggle to the British 

 islands. The name albatros, it may be mentioned, has a distinctly curious origin, 

 being a corruption of the Spanish and Portuguese alcatraz, or alcaduz, which is 

 commonly applied to the pelican, as well as to other large birds, and is itself a 

 derivative from the Arabic al-cadous, which is again derived from kudos, the Greek 

 term for a water-pot or bucket, and more especially the leather bucket of an old- 

 fashioned irrigating machine, such as those still in use on the Nile. The trans- 

 ference of the name to the pelican, which was supposed to carry water to its young 

 in the great pouch of skin attached to the lower half of the beak, is perfectly easy 

 to understand. The generic name Diomedia, meaning the bird of Diomedes, and 

 the equivalent of Pliny's Avis Diomedece, appears to belong of right to a species 

 of shearwater inhabiting certain Mediterranean islands. But the misapplication 

 of names in connection with these birds does not end here, for the name " molly - 

 mauk," applied by sailors to the yellow-beaked albatros (D. culminata), of Tristan 



