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 which the genital pleurae are quite obsolete, and yet lateral septa occur (e.g. Ptychodera ruficollis), seeming to indicate that the pleural folds have in such cases been secondarily suppressed.

Development.—The development of Balanoglossus takes place according to two different schemes, known as direct and indirect, correlated with the occurrence in the group of two kinds of ova, large and small. Direct development, in which the adult form is achieved without striking metamorphosis by a gradual succession of stages, seems to be confined to the family Balanoglossidae. The remaining two families of Enteropneusta, Ptychoderidae and Spengelidae, contain species of which probably all pursue an indirect course of development, culminating in a metamorphosis by which the adult form is attained. In these cases the larva, called Tornaria, is pelagic and transparent, and possesses a complicated ciliated seam, the longitudinal ciliated band, often drawn out into convoluted bays and lappets. In addition to this ciliated band the form of the Tornaria is quite characteristic and unlike the adult. The Tornaria larva offers a certain similarity to larvae of Echinoderms (sea-urchins, star-fishes, and sea-cucumbers), and when first discovered was so described. It is within the bounds of possibility that Tornaria actually does indicate a remote affinity on the part of the Enteropneusta to the Echinoderms, not only on account of its external form, but also by reason of the possession of a dorsal water-pore communicating with the anterior body-cavity. In the direct development Bateson showed that the three divisions of the coelom arise as pouches constricted off from the archenteron or primitive gut, thus resembling the development of the mesoblastic somites of Amphioxus. It would appear that while the direct development throws light upon the special plan of organization of the Enteropneusta, the indirect development affords a clue to their possible derivation. However this may be, it is sufficiently remarkable that a small and circumscribed group like the Enteropneusta, which presents such a comparatively uniform plan of composition and of external form, should follow two such diverse methods of development.

Distribution.—Some thirty species of Balanoglossus are known, distributed among all the principal marine provinces from Greenland to New Zealand. The species which occurs in the English Channel is Ptychodera sarniensis. The Ptychoderidae and Spengelidae are predominantly tropical and subtropical, while the Balanoglossidae are predominantly arctic and temperate in their distribution. One of the most singular facts concerning the geographical distribution of Enteropneusta has recently been brought to light by Benham, who found a species of Balanoglossus, sensu stricto, on the coast of New Zealand hardly distinguishable from one occurring off Japan. Finally, Glandiceps abyssicola (Spengelidae) was dredged during the “Challenger” expedition in the Atlantic Ocean off the coast of Africa at a depth of 2500 fathoms.

.—W. Bateson, “Memoirs on the Direct Development of Balanoglossus,” ''Quart. Journ. Micr. Sci. (vols. xxiv.-xxvi., 1884–1886); W. B. Benham, “Balanoglossus otagoensis, n. sp,” Q. J. M. S.'' (vol. xlii. p. 497, 1899); Yves Delage and Éd. Hérouard, Traité de zoologie concrète (t. viii.), “Les Procordés” (1898); S. F. Harmer, “Note on the Name Balanoglossus,” ''Proc. Camb. Phil. Soc. (x. p. 190, 1900); T. H. Morgan, “Memoirs on the Indirect Development of Balanoglossus,” Journ. Morph. (vol. v., 1891, and vol. ix., 1894); W. E. Ritter, “Harrimania maculosa, a new Genus and Species of Enteropneusta from Alaska,” Papers from the Harriman Alaska Exhibition (ii.), Proc. Washington Ac. (ii. p. 111, 1900); J. W. Spengel, “Die Enteropneusten,” Eighteenth Monograph on the Fauna und Flora des Golfes von Neapel (1893); A. Willey, “Enteropneusta from the South Pacific, with Notes on the West Indian Species,” Zool. Results (Willey), part iii., 1899; see also Q. J. M. S. (vol. xlii. p. 223, 1899); J. P. Hill, “The Enteropneusta of Funafuti,” Mem. Austral. Mus.'' (iii., 1897–1898); M. Caullery and F. Mesnil, “Balanoglossus Kochleri, n. sp. English Channel,” ''C. R. Soc. Biol.'' lii. p. 256 (1900).

BALARD, ANTOINE JERÔME (1802–1876), French chemist, was born at Montpellier on the 30th of September 1802. He started as an apothecary, but taking up teaching he acted as chemical assistant at the faculty of sciences of his native town, and then became professor of chemistry at the royal college and school of pharmacy and at the faculty of sciences. In 1826 he discovered in sea-water a substance which he recognized as a previously unknown element and named bromine. The reputation brought him by this achievement secured his election as successor to L. J. Thénard in the chair of chemistry at the faculty of sciences in Paris, and in 1851 he was appointed professor of chemistry at the Collège de France, where he had M. P. E. Berthelot first as pupil, then as assistant and finally as colleague. He died in Paris on the 30th of April 1876. While the discovery of bromine and the preparation of many of its compounds was his most conspicuous piece of work, Balard was an industrious chemist on both the pure and applied sides. In his researches on the bleaching compounds of chlorine he was the first to advance the view that bleaching-powder is a double compound of calcium chloride and hypochlorite; and he devoted much time to the problem of economically obtaining soda and potash from sea-water, though here his efforts were nullified by the discovery of the much richer sources of supply afforded by the Stassfurt deposits. In organic chemistry he published papers on the decomposition of ammonium oxalate, with formation of oxamic acid, on amyl alcohol, on the cyanides, and on the difference in constitution between nitric and sulphuric ether. BALA SERIES, in geology, a series of dark slates and sandstones with beds of limestone which occurs in the neighbourhood of Bala, Merionethshire, North Wales. It was first described by A. Sedgwick, who considered it to be the upper part of his Cambrian System. The series is now placed at the top of the Ordovician System, above the Llandeilo beds. The Bala limestone is from 20 to 40 ft. thick, and is recognizable over most of North Wales; it is regarded as the equivalent of the Coniston limestone of the Lake District. The series in the type area consists of the Hirnant limestone, a thin inconstant bed, which is separated by 1400 ft. of slates from the Bala limestone, below this are more slates and volcanic rocks. The latter are represented by large contemporaneous deposits of tuff and felsitic lava which in the Snowdon District are several thousand feet thick. In South Wales the Bala Series contains the following beds in descending order:—the Trinucleus seticornis beds (Slade beds, Redhill shales and Sholeshook limestone), the Robeston Wathen beds, and the Dicranograptus shales. The typical graptolites are, in the upper part, Dicellograptus anceps and D. complanatus; in the lower part, Pleurograptus linearis and Dicranograptus Clingani. In Shropshire this series is represented by the Caradoc and Chirbury Series; in southern Scotland by the Hartfell and Ardmillan Series, and by similar rocks in Ireland. See and. BALASH (in the Greek authors, Balas; the later form of the name Vologaeses), Sassanian king in 484-488, was the brother and successor of Pērōz, who had died in a battle against the Hephthalites (White Huns) who invaded Persia from the east. He put down the rebellion of his brother Zareh, and is praised as a mild and generous monarch, who made concessions to the Christians. But as he did nothing against his enemies, he was, after a reign of four years, deposed and blinded, and his nephew, Kavadh I., raised to the throne.

BALASORE, a town and district of British India, in the Orissa division of Bengal. The town is the principal one and the administrative headquarters of the district, and is situated on the right bank of the river Burabalang, about 7 m. from the sea-coast as the crow flies and 16 m. by the river. There is a station on the East Coast railway. The English settlement of Balasore, formed in 1642, and that of Pippli in its neighbourhood seven years earlier, became the basis of the future greatness of the British in India. The servants of the East India Company here fortified themselves in a strong position, and carried on a brisk investment in country goods, chiefly cottons and muslins. They flourished in spite of the oppressions of the Mahommedan governors, and when needful asserted their claims to respect by arms. In 1688, affairs having come to a crisis, Captain William Heath, commander of the company’s ships, bombarded the town. In the 18th century Balasore rapidly declined in importance, on account of a dangerous bar which formed across the mouth of the river. At present the bar has 12 to 15 ft. of water at spring-tides, but not more than 2 or 3 ft. at low water in the dry season. Large ships have to anchor outside in the open roadstead. The town still possesses a large maritime trade, despite the silting-up of the river mouth. Pop. (1901) 20,880.

The district forms a strip of alluvial land between the hills and the sea, varying from about 9 to 34 m. in breadth; area, 2085 sq. m. The hill country rises from the western boundary line. The district naturally divides itself into three well-defined tracts—(1) The salt tract, along the coast; (2) The arable tract, or rice country; and (3) The submontane tract, or jungle lands. The salt tract runs the whole way down the coast, and forms a desolate strip a few miles broad. Towards the beach it rises into sandy ridges, from 50 to 80 ft. high, sloping inland and covered with a