SHEATHBILL, a bird so-called by Pennant in 1781 (Gen. Birds, ed. 2, p. 43) from the horny case' which ensheaths the basal part of its bill. It was first made known from having been met with on New-Year Island, off the coast of Staten Land, where Cook anchored on New Year's eve 1774.2 A few days later he discovered the islands that now bear the name of South Georgia, and there the bird was again found, - in both localities frequenting the rocky shores. On his third voyage, while seeking some land reported to have been found by Kerguelen, Cook in December 1776 reached the cluster of desolate islands now generally known by the name of the French explorer, and here, among many other kinds of birds, was a Sheathbill, which for a long while no one suspected to be otherwise than specifically identical with that of the western Antarctic Ocean ; but, as will be seen, its distinctness has been subsequently admitted.

The Sheathbill, so soon as it was brought to the notice of naturalists, was recognized as belonging to a genus hitherto unknown, and the elder Forster in 1788 (Enchiridion, p. 37) conferred upon it, from its snowy plumage, the name Chionis, which has most properly received general acceptance, though iu the same year the compiler Gmolin termed the genus l'aginalis, as a rendering of Pennant's English name, and the species alba. It has thus become the Chionis alba of ornithology. It is about the size of and has much the aspect of a Pigeon ;3 its plumage is pure white, its bill somewhat yellow at the base, passing into pale pink towards the tip. Round the eyes the skin is bare, and beset with cream-coloured papilla, while the legs are bluish-grey. The second or eastern species, first discriminated by Dr Hartlaub (Rev. Zoologigne, 1841, p. 5 ; 1842, p. 402, pl. 2)4 as C. minor, is smaller in size, with plumage just as white, but having the bill and bare skin of the face black and the legs much darker. The form of the bill's "sheath" in the two species is also quite different, for in C. alba it is almost level throughout, while in C. minor it rises in front like the pommel of a saddle. Of the habits of the western and larger species not much has been recorded. It gathers its food, consisting chiefly, as Darwin and others have told us, of sea-weeds and shell-fish, on rocks at low water ; but it is also known to eat birds' eggs. There is some curiously conflicting evidence as to the flavour of its flesh, some asserting that it is wholly uneatable, and others that it is palatable, - a difference which may possibly be due to the previous diet of the particular example tasted, to the skill of the cook, or the need of the taster. Though most abundant as a shore-bird, it is frequently met with far out at sea, and its most northern recorded limit is by Fkurieu ( Vey. de Marchand, i. p. 19), in lat. 44* S., some 260 miles from the eastern coast of Patagonia. It is not uncommon on the Falkland Isles, where it is said to breed (This, 1861, p. 154), though confirmation of the report is as yet wanting, and from thence is found at both extremities of the Strait of Magellan, and southward. to Louis-Philippe Land in lat. 60° S. On the other hand, thanks to the naturalists of the British and United States expeditions to Kerguelen Land for the observation of the transit of Venus in 1874, especially Mr Eaton (Philos. Transactions, clxviii. pp. 103-105) and Dr Kidder (Bull. U. S. Xational Mu-scum, 1875, No. 2, p. 1-4), much more has been recorded of the eastern and smaller species, which had already been ascertained by Mr Layard (Proc. Zool. Society, 1871, p. 57, pl. iv. fig. 7) to breed on the Crozet Islands,4 and was found to do so still more numerously on Kerguelen, while it probably frequents Prince Edward's Islands for the same purpose. The eggs, of which a considerable number have now been obtained, though of peculiar appearance, bear an unmistakable likeness to those of some Plovers, while occasionally exhibiting a resemblance - of little significance, however - to those of the Tropic-birds.

The systematid position of the Sheathbills has been the subject of much hesitation - almost useless since 1836, when De Blainville (Ann. Sc. Xaturelles, ser. 2, vi. p. 97) made known certain anatomical facts proving their affinity to the OYSTER-CATCHERS (vol. xvii. p. 111), though pointing also to a more distant relationship with the Guus (vol. xi. p. 274). These he afterwards described more fully (Yoy. " Bonite," Zoologie, i. pt. 3, pp. 107-132, pl. 9), so as to leave no doubt that Chionis was a form intermediate between those groups. Yet some writers continued to refer it to the Gallinx and others to the Columbx. The matter may now be regarded as settled for ever. In 1876 Dr Reichenow in Germany (Jour. f. Om., 1876, pp. 84-89) and in America Drs Kidder and Cones (Bull. U. S. .1.Vat. Museum, No. 3, pp. 85-116) published elaborate accounts of the anatomy of C. minor, the first wholly confirming the view of De Blainville, the last two a agreeing with him in the main, but concluding that the Sheathbills formed a distinct group Chionomorphx, in rank equal to the Cecomorpltx and Charadriomorphw of Prof. Huxley (which are, to speak roughly, the Garim and Limicolea of older systematists), and regarding this group as being " still nearer the common ancestral stock of both." These authors also wish to separate the two species generically; but their proposals are considered needless by Garrod (P. Z. S., 1877, p. 417) and M. Alph. Milne-Edwards (Ann. Sc. Naturelles, ser. 6, xiii. art. 4, p. 24). The opinions of De Blainville and Dr Reichenow are borne out by the observations of 'Mr Eaton (lee. cit.), and no one knowing the habits of an Oyster-catcher can read his remarks without seeing how nearly related the two forms are. Their differences may perhaps justify the separation of each form into what is vaguely called a "Family," but the differences will be seen by the comparative anatomist to be of slight importance, and the intimate affinity of the Gavin and Limicam, already recognized by Prof. Parker and some of the best taxonomers (cf. ORNITHOLOGY, VOL xviii. p. 45) is placed beyond dispute.? (A. N.)