are used by the birds as a playing-house or 'run,' as it is termed, and are used by the males to attract the females. The 'run' of the Satin-bird is much smaller, being less than one foot in length, and moreover differs from that just described in being decorated with the highly-coloured feathers of the Parrot-tribe; the Chlamydera, on the other hand, collects around its 'run' a quantity of stones, shells, bleached bones, etc.; they are also strewed down the centre within."

This statement, marvellous as it seemed, has been proved by many subsequent observers to be strictly true, and it must be borne in mind that these structures,1 each of which as above described he next year (1 Sept. 1841) figured (B. Austral. iv. pls. 8, 10), have nothing to do with nests of the birds-indeed, their mode of nidification, which was not made known until some years later, presents no extraordinary feature. Moreover, the birds will build their "bowers" in confinement, and therein disport themselves, as has been repeatedly shewn in the Zoological Gardens 2 by the Satin-bird last mentioned, Ptilorhynchus violaceus. Subsequently it was found that the Regent-bird, Sericulus melinus, a species long before known, had the habit of making a "bower" of similar kind, though built, so to speak, in another style of architecture, and having for its chief decoration the shells of a small species of Helix.

The account of these curious birds which may be most conveniently consulted is that in Gould's Handbook to the Birds of Australia (i. pp. 441-461), published in 1865; but since that time discoveries still more wonderful have been made. A bird of New Guinea, originally referred to the genus Ptilorhynchus, but now recognized as Amblyornis inornatus, has been found by Sign. Beccari to present not only a modification of bower-building, but an appreciation of beauty perhaps unparalleled in the animal world. His interesting observations (Annali del Mus. Civ. de Storia Nat. di Genova, ix. pp. 382-400, tav. viii.) shew that this species, which he not inaptly calls the "Gardener" (Gjardiniere), builds at the foot of a small tree a kind of hut or cabin (capanna) some two feet in height, roofed with orchid-stems that slope to the ground, regularly

1 Gould brought home with him at least two examples, which he gave to the British Museum. There is no reason to suppose that this extraordinary habit had been described before the date above given, or that the name "Bower-bird" had been previously used, and yet we find Trelawny in his Memoirs of Shelley, published in 1878, referring to himself (i. p. 136) as saying, in a conversation not later than 1822, "You two have built your nest after the fashion of the Australian bower-birds"!

2 The ordinary visitor to these gardens seems to regard the structures of the Bower-birds without any intelligent interest. He perhaps supposes that they are the handiwork of one or other of the keepers. From my own long connexion with the Zoological Society, I think I am able to state that neither in this nor anything else of the kind is any deception practised. The Bower-birds are supplied with materials, and that is all.

radiating from the central support, which is covered with a conical mass of moss, and sheltering a gallery round it. One side of this hut is left open, and in front of it is arranged a bed of verdant moss, bedecked with blossoms and berries of the brightest colours. As these ornaments wither they are removed to a heap behind the hut, and replaced by others that are fresh. The hut is circular, and some three feet in diameter, and the mossy lawn in

(After Beccari. From The Gardeners' Chronicle, N.S., vol. ix. p. 333.) front of it of nearly twice that expanse. Each hut and garden are, it is believed, though not known, the work of a single pair of birds, or perhaps of the male only; and it may be observed that this species, as its trivial name implies, is wholly inornate in plumage.1 Not less remarkable is the more recently described

1 Another species referred to the same genus, A. subalaris, the female of which was originally described by Mr. Sharpe (Journ. Linn. Soc. xvii. p. 40) as being still more dingy, turned out to have the male embellished with a wonderful crest of reddish-orange (Finsch and Meyer, Zeitschr. f. ges. Orn. 1885, p. 390, tab. xxii.).

"bower" of Prionodura, a genus of which the male, like the Regentbird, is conspicuous for his bright orange coloration. This structure is said by Mr. Devis (Trans. Roy. Soc. Queensland, 14 June 1889) to be piled up almost horizontally round the base of a tree to the height of from 4 to 6 feet, and around it are a number of hut-like fabrics, having the look of a dwarfed native camp. Allied to the forms already named are two others, Scenopous and Ailuroedus, which, though not apparently building "bowers," yet. clear a space of ground some 8 or 9 feet in diameter, on which to display themselves, ornamenting it "with tufts and little heaps of gaily tinted leaves and young shoots" (Ramsay, Proc. Zool. Soc. 1875, p. 592). The former of them, which, according to Mr. Lumholtz (Among Cannibals, pp. 139, 140), covers a space of about a square yard with large fresh leaves neatly laid, and removes them as they decay, inhabits Queensland, and to the latter belongs the "Cat-bird," so well known to Australians from its loud, harsh, and extraordinary cries.

By most systematists these birds are placed among the Paradiseida (BIRD-OF-PARADISE); but in

the British Museum Catalogue of Birds (vi. pp. 380-396) they are to be found in the "limbo large and broad" of Timeliida-though allowed the rank of a subfamily "Plilonorhynchina," the name being taken from the feathered and not the bare (as might from its etymology have been expected) condi

tion of the base of the bill shewn in the figure of that part in the Satin-bird.

BRACHIAL ARTERY, see VASCULAR SYSTEM: BRACHIAL PLEXUS, see NERVOUS SYSTEM.

BRAIN, the part of the Central NERVOUS SYSTEM which is enclosed by the cranium, and in Birds consists of three principal divisions, named after their position-Hind- Mid- and Forebrain. The hindbrain is composed of the medulla oblongata, the direct and comparatively little modified continuation of the spinal cord, and of the cerebellum, these two parts being connected with each other by the pedunculi or crura cerebelli. The midbrain contains the peduncles of the great or forebrain, and the cortex or rind of the optic lobes. The forebrain is subdivided into the thalamencephalon and into the cerebral hemispheres. The ventral parts of the thalamencephalon form the hypophysis and the chiasma or crossing of the optic nerves, the lateral parts contain the inner portions of the optic lobes, which are partly homologous with

the corpora bigemina of Mammals, and the optic thalami; the dorsal roof forms the epiphysis or pineal gland, the corpus callosum and the anterior commissure, both of which consist of bundles of white nerve fibres and connect the right with the left hemisphere. The ventral portion of the hemispheres consists of the corpora striata, which are masses of grey brain-substance, and of the olfactory lobes, which mark the anterior end of the brain.

The central canal, which runs through the spinal cord, is continued into the brain, and forms the fourth ventricle in the hindbrain, extending dorsally into the cerebellum; and is then continued as "aquæductus Sylvii" through the midbrain, with lateral extensions into the optic lobes. The dilatation of this canal in the thalamencephalon is the third ventricle: it extends ventrally towards the hypophysis as the infundibulum, in a similar way

dorsally towards the epiphysis, and communicates through the foramen of Monro with the second and first ventricles; these being the cavities of the two hemispheres.

The hypophysis cerebri or pituitary body is lodged in the "sella turcica," a niche or recess formed by the anterior and posterior basisphenoid bones. This peculiar body is probably the degenerated remnant of a special sense-organ in the mouth of early Vertebrata, it being developed partly as an outgrowth from the roof of the mouth which fuses with a corresponding growth from the brain and then loses its connexion with the mouth.

The epiphysis cerebri or pineal body is the remnant of a sense-organ, possibly visual, as it is still functional in many Lizards possessing a lens, a retina-like accumulation of black pigment and a nerve, but quite degenerated in all Birds and Mammals.

The cerebellum of Birds is homologous only with the "worm or middle portion of the cerebellum of Mammals, the lateral lobes being absent, although a pair of flocculi are present. Externally it exhibits a number of transverse furrows, which divide it into

lamellæ. On a vertically longitudinal, or "sagittal," section, it has

a beautiful tree-like appearance.

cavity branch-like

white medullary fibres spread out, surrounded by a layer of reddish ganglionic cells, followed by larger ganglia (Purkinje's layer), and externally covered by a grey mantle of smaller ganglionic cells. Such a thin section, especially when stained with carmine, forms a fascinating object for the microscope, and is easily made.

The surface of the cerebral hemispheres in Birds exhibits no convolutions or gyrations as in the higher Mammals. In the Ratitæ and in many Passeres the surface is entirely smooth, but in Swimmers, Waders, Pigeons, Fowls, and Birds

From the walls of the central

(After A. Meckel.)

I-XII, the twelve pairs of cranial nerves; Ch. Chiasma of the

of-Prey, there is a optic nerves cut across; Fl. Flocculus; H. Hypophysis; L.o. very slight furrow Optic lobe; Lq. Laqueus; F.S. Sylvian fissure; Sp. I. First spinal which might be

nerve.

compared with the Sylvian fissure. There is also very little grey substance in the surface layers of the hemispheres. Various attempts have been made, by Tiedemann,1 Serres,2 Leuret,3 and Bumm, to compare the weight of the whole brain with that of the body, or

1 Anatomie und Naturgeschichte der Vögel. Heidelberg: 1810.

2 Anatomie comparée du cerveau. Paris: 1824.

3 Anatomie comparée du système nerveux. Paris: 1839-57.

4

4 Das Grosshirn der Vögel. Zeitschr. für wissensch. Zool. xxxviii. (1883) pp. 430-466, tabb. xxiv. -xxv.