twentieth day the beak, furnished with the hard "egg-tooth," is thrust through the inner shell membrane, and the bird begins to breath the air contained in the chamber. Thereupon the pulmonary circulation becomes functionally active and blood ceases to flow through the umbilical vessels from and to the allantois. The latter shrivels up, the navel becomes completely closed, and the chick by repeated filing motions pierces the shell at the broad end of the egg with its egg-tooth. A small crack in the shell is sufficient to destroy the surprising strength of the intact egg, the chick casts off the dried, now no longer useful, remains of allantois and amnion, and steps out into the world.

The length of the period of incubation seems to depend upon, first, the state of perfection in which the young bird leaves the egg, the Nidifugæ requiring a much longer time than the Nidicolæ ; secondly, the size of the bird,-large birds requiring more days than small birds; thirdly, climate and season, because an occasional slight cooling of the eggs retards the development of the embryo. The amount of cooling will naturally be greater in cold than in hot climates, while the temperature of the sitting bird varies within small limits only. However, there seem to be no observations made on the question if there is a difference in the length of incubation between polar and tropical individuals of the same species. Experience with artificial incubators has shewn that during the earliest days of incubation the growth of the embryo can be much retarded or even be stopped temporarily by a temperature below the normal point; on the other hand, a higher than normal temperature does not shorten the time of incubation but is rather detrimental to the embryo's life (cf. W. Evans, Ibis, 1891, pp. 52-93).

EMEU, evidently from the Portuguese Ema,1 a name which has in turn been applied to each of the earlier-known forms of Ratite Birds, but has in all likelihood finally settled upon that which inhabits Australia, though, until less than a century ago, it was given by most authors to the bird now commonly called CASSOWARY.

1 By Moraes (1796) and Sousa (1830) the word is said to be from the Arabic Naáma or Na'êma, an Ostrich (Struthio camelus); but no additional evidence in support of the assertion is given by Dozy in 1869 (Glossaire des mots espagnols et portugais dérivés de l'arabe. Ed. 2, p. 260). According to Gesner in 1555 (lib. iii. p. 709), it was the Portuguese name of the Crane, Grus communis, and had been transferred with the qualifying addition of "di Gei" (i.e. Ground-Crane) to the Ostrich. This statement is confirmed by Aldrovandus (lib. ix. cap. 2). Subsequently, but in what order can scarcely now be determined, the name was naturally enough used for the Ostrich-like birds inhabiting the lands discovered by the Portuguese, both in the Old and in the New World. The last of these are now known as Rheas, and the preceding as Cassowaries.

Of the Emeus (as the word is now restricted) the best-known is the Casuarius nova-hollandiæ of Latham, made by Vieillot the type of his genus Dromæus,1 whence the name of the Family, Dromæidæ, is taken. This bird immediately after the colonization of New South Wales (in 1788) was found to inhabit the southeastern portion of Australia, where, according to Hunter (Hist. Journ. etc. pp. 409, 413), the natives called it Maracry, Marryang,

or Maroang; but it has now been so hunted down that not an example remains at large in the districts that have been fully settled. It is said to have existed also on the islands of Bass's Straits and in Tasmania, but it has been extirpated in both,

1 The obvious misprint of Dromeicus in this author's work (Analyse &c., p. 54) has been foolishly followed by many naturalists, forgetful that he corrected it a few pages further on (p. 70) to Dromaius-the properly latinized form of which is Dromæus.

without, so far as is known, any ornithologist having had the opportunity of determining whether the race inhabiting those localities was specifically identical with that of the mainland or distinct.1 Next to the OSTRICH the largest of existing birds, the Emeu is an inhabitant of the more open country, feeding on fruits, roots, and herbage, and generally keeping in small companies. The nest is a shallow pit scraped in the ground, and from nine to thirteen eggs, in colour varying from a light bluish-green to a dark bottle-green, are laid therein. These are hatched by the cock-bird, the period of incubation lasting from 70 to 80 days. The young at birth are striped longitudinally with dark markings on a light ground. A remarkable structure in Dromæus is a singular opening in the front of the windpipe, communicating with a tracheal pouch. This has attracted the attention of several anatomists, and has been well described by Dr. Murie (Proc. Zool. Soc. 1867, pp. 405-415).2 Various conjectures have been made as to its function, the most probable of which seems to be that it is an organ of sound in the breeding-season, at which time the henbird has long been known to utter a remarkably loud booming note. Due convenience being afforded to it, the Emeu thrives well, and readily propagates its kind in Europe. Like the South American RHEA it will take naturally to the water, and examples have been seen voluntarily swimming a wide river.

The existence in Australia of a second species of Dromæus had long been suspected, and Broderip in 1842 stated (Penny Cyclop. xxiii. p. 145) that Mr. Gould had even supplied a name (D. parvulus) for it; but there can be little doubt that this suggestion was founded on a mistake. However, in 1859 Mr. Bartlett described, under the name of D. irroratus, what has since been generally admitted to be a good species, and it now seems certain that this fills in Western Australia the place occupied by the olderknown form in the eastern part. It is a more slender bird, and when adult has the feathers barred with white and dark-grey ending in a black spot which has a rufous margin, while those of D. nova-hollandiæ are of a uniform blackish grey from the base to near the tip, which is black with a broad subterminal rufous band. Both species have been figured from admirable drawings by Mr. Wolf (Trans. Zool. Soc. iv. pls. 75, 76), and interesting particulars as to their domestication in England are given by Mr. Harting (Ostriches and Ostrich Farming, pp. 131-174).

1 Latham (Gen. Hist. B. viii. p. 384, pl. 138) in 1823 described and absurdly figured what he called “Van Diemen's Cassowary" from one of two young birds exhibited alive in London; but there is nothing to shew that they really came from Tasmania, and as they were apparently the only Emeus he had ever seen, he had no means of determining whether they differed from the Australian form. 2 See also Gadow (Zoolog. Jahrb. v. pp. 636-638), and above, AIR-SACS.

EMMET-HUNTER, a common local name of the WRYNECK.

ERN or ERNE, Scandin. Orn, the Sea-EAGLE; but hardly used now except in poetry or as the name of a pleasure-yacht.

ERODY (corrupted from Herodias, a Heron) Latham's name (Gen. Hist. B. ix. p. 139) for Dromas ardeola (CRAB-PLOVER).

EROLIA, a genus proposed by Vieillot (Nouv. Anab. p. 55), and the name Englished by Stephens in 1819 (Shaw's Zoology, xi. p. 497), but believed to be founded on a specimen of Tringa subarquata (SANDPIPER) which had lost its hind toes.

ERYTHRISM, the abnormal replacement of other colours, generally green or yellow, by red (see COLOUR and HETEROCHROSIS). ESTRIDGER, an old word signifying a Falconer.

EXTERMINATION, literally a driving out of bounds or banishment, is a process which, intentionally or not, has been and still is being carried on in regard to many more species of Birds than most people-not excepting professed ornithologists-seem to recognize, and one that has frequently led to the Extinction,1 or dying out, of the species affected. The inhabitants of islands are especially subject to this fate. In them each species has long been brought into harmony with its circumstances, and relations with its fellow-creatures have so far become mutually adjusted that in the long run the balance between them is preserved, and the stock of each remains the same one year with another. But the appearance

on the scene of man, and especially of civilized man, upsets the equilibrium. Even if he do not immediately begin to bring the virgin soil under cultivation by felling the primeval forest or burning the brushwood, he almost always introduces certain animals which make war on the aboriginal population-directly in the case of Cats and Rats, indirectly in that of Goats and Rabbits, or both ways in that of Hogs. Against such enemies, whether forcibly attacking them or insidiously robbing them of food, the most part of the indigenous species are unprepared and absolutely helpless. In the majority of instances each of the islands so colonized has its own peculiar Fauna, largely consisting, that is, of species not found elsewhere, and if the island be small it is soon overrun by the newcomers, and its ancient inhabitants with difficulty preserve their existence, or wholly succumb.

The best known if not the most remarkable case of this kind is that of the DODO, Didus ineptus, which, on the rediscovery of Cerne,

1 In some instances the still stronger word, Extirpation, or rooting out, might be appropriately used; but this would be most applicable in those where destruction of the species is purposely intended, and attempts of that kind have rarely proved to be successful, unless carried on for a long period of time, or by poison.

or Mauritius, by the Dutch under Van Neck at the end of the 16th century, was found to inhabit that island. Voyagers have vied with each other in describing or depicting its uncouth appearance, and its name has almost passed into a byword expressive of all that is effete. Clumsy, flightless, and defenceless, it soon succumbed, not so much to the human invaders of its realm as to the domestic beasts-especially Hogs 1-which accompanied them, and there gaining their liberty, unchecked by much of the wholesome discipline of nature, ran riot, to the utter destruction (as will be seen) of no inconsiderable portion of the Mauritian fauna.

EXTINCT CRESTED PARROT OF MAURITIUS, Lophopsittacus mauritianus. Adapted from a tracing by M. A. Milne-Edwards of the original drawing in a MS. Journal kept during Wolphart Harmanszoon's voyage to Mauritius, A.D. 1601-1602 (cf. Proc. Zool. Soc. 1875, p. 350).

But the Dodo is not the only member of its Family that has vanished. The little island which has successively borne the name of Mascaregnas, England's Forest, Bourbon, and Réunion, and lies. to the southward of Mauritius, had also an allied Bird, now dead

1 In La Roque's account of the Voyage de l'Arabie Heureuse (Paris: 1715) in 1708-10 (the first made by the French) it is stated that the ships touched at Mauritius in September 1709 and that "de l'autre côté de l'isle audelà des montagnes on trouvoir force sangliers, qui faisoient un tel dégât, qu'on avoit depuis peu ordonné une chasse générale pour les détruire, & que les habitans s'étant assemblez, on en tua en un jour plus de quinze cens (p. 175). A few days after he writes: "en me promenant dans leur jardin, j'eus le plaisir de voir de derriere la haye plus de quatre mille singes dans le champ voisin" (p. 183). In regard to