may be partially absorbed. In the case of medicated baths we therefore only look (in addition to the action of heat and cold, or more properly to the abstraction or communication and retention of heat) to any stimulant action on the skin that the ingredients of the bath may possess.

The powerful influence of water on the capillaries of the skin, and the mode and extent of that operation, depend primarily on the temperature of the fluid. The human system bears changes of temperature of the air much better than changes of the temperature of water. While the temperature of the air at 75° may be too warm for the feelings of many people, a continued bath at that temperature is felt to be cold and depressing. Again, a bath of 98° to 102° acts far more excitingly than air of the same temperature, both because, being a better conductor, water brings more heat to the body and because it suppresses the perspiration which is greatly augmented by air of that temperature. Further, a temperature a few degrees below blood heat is that of indifferent baths, which can be borne longest without natural disturbance of the system.

Cold baths act by refrigeration, and their effects vary according to the degree of temperature. The effects of a cold bath, the temperature not being below 50°, are these:-there is a diminution of the temperature of the skin and of the subjacent tissues; there is a certain feeling of shock diffused over the whole surface, and if the cold is intense it induces a slight feeling of numbness in the skin. It becomes pale and its capillaries contract. The further action of a cold bath reaches the central nervous system, the heart and the lungs, as manifested by the tremor of the limbs it produces, along with a certain degree of oppression of the chest and a gasping for air, while the pulse becomes small and sinks. After a time reaction takes place, and brings redness to the skin and an increase of temperature.

The colder the water is, and the more powerful and depressing its effects, the quicker and more active is the reaction. Very cold baths, anything below 50°, cannot be borne long. Lowering of the temperature of the skin may be borne down to 9°, but a further reduction may prove fatal. The diminution of temperature is much more rapid when the water is in motion, or when the bather moves about; because, if the water is still, the layer of it in immediate contact with the body is warmed to a certain degree.

A great deal depends on the form of the cold bath; thus one may have (1) Its depressing operation,-with a loss of heat, retardation of the circulation, and feeling of weariness, when the same water remains in contact with the skin, and there is continuous withdrawal of heat without fresh stimulation. This occurs with full or sitz baths, with partial or complete wrapping up the body in a wet sheet which remains unchanged, and with frictions practised without removing the wet sheets. (2) Its exciting operation, with quickening of the action of the heart and lungs, and feeling of glow and of nervous excitement and of increased muscular power. These sensations are produced when the layer of water next the body and heated by it is removed, and fresh cold water causes fresh stimulus. These effects are produced by full baths with the water in motion used only for a short time, by frictions when the wet sheet is removed from the body, by douches, shower baths, bathing in rivers, &c. The depressing operation comes on much earlier in very cold water than in warmer; and in the same way the exciting operation comes on faster with the colder than with the warmer water. The short duration of the bath makes both its depressing and its exciting action less; its longer duration increases them; and if the baths be continued too long, the protracted abstraction of animal heat may prove very depressing.

Tepid baths, 85° to 95°.-The effects of a bath of this temperature are confined to the peripheral extremities of the nerves, and are so slight that they do not reach the central system. There is no reaction, and the body temperature remains unchanged. Baths of this kind can be borne for hours with impunity.

Warm baths from 96° to 104°.-In these the action of the heat on the peripheral surface is propagated to the central system, and causes reaction, which manifests itself in moderately increased

flow of the blood to the surface, and in an increased frequency of pulse.

With a hot bath from 102° up to Iro° the central nervous and circulating systems are more affected. The frequency of the pulse increases rapidly, the respiration becomes quickened, and is interrupted by deep inspirations. The skin is congested, and there is profuse perspiration.

Very hot baths.-Everything above 110° feels very hot; anything above 120° almost scalding. Baths of from 119° to 126° have caused a rise of 2° to 41° in the temperature of the blood. Such a bath can be borne for only a few minutes. It causes great rapidity of the pulse, extreme lowering of the blood-pressure, excessive congestion of the skin, and violent perspiration. In the use of hot baths a certain amount of vapour reaches the parts of the body not covered by the water, and is also inhaled. Vapour baths produce profuse perspiration and act in cleansing the skin, as powerful hot water baths do. Vapour, owing to its smaller specific heat, does not act so fast as water on the body. A vapour bath can be borne for a much longer time when the vapour is not inhaled. Vapour baths can be borne hotter than water baths, but cannot be continued too long, as vapour, being a bad conductor, prevents radiation of heat from the body. A higher heat than 122° is not borne comfortably. The vapour bath though falling considerably short of the temperature of the hot air bath, raises the temperature much more.

Hot air baths differ from vapour baths in not impeding the respiration as the latter do, by depositing moisture in the bronchial tubes. The lungs, instead of having to heat the inspired air, are subjected to a temperature above their own. Hot air baths, say of 135°, produce more profuse perspiration than vapour baths. If very hot, they raise the temperature of the body by several degrees. Vapour baths, hot air baths, and hot water baths agree in producing violent perspiration. As perspiration eliminates water and effete matter from the system, it is obvious that its regulation must have an important effect on the economy. In comparing the general effects of cold and hot baths, it may be said that while the former tend to check perspiration, the latter favour it.

The warm bath causes swelling and congestion of the capillaries of the surface in the first instance; when the stimulus of heat is withdrawn their contraction ensues. A cold bath, again, first causes a contraction of the capillaries of the surface, which is followed by their expansion when reaction sets in. A warm bath elevates the temperature of the body, both by bringing a supply of heat to it and by preventing the radiation of heat from it. It can be borne longer than a cold bath. It draws blood to the surface, while a cold bath favours internal congestions.

But baths often produce injurious effects when used injudiciously. Long continued warm baths are soporific, and have, owing to this action, often caused death by drowning. The effects of very hot baths are swimming in the head, vomiting, fainting, congestion of the brain, and, in some instances, apoplexy.

The symptoms seem to point to paralysis of the action of the heart. It is therefore very evident how cautious those should be, in the use of hot baths, who have weak hearts or any obstruction to the circulation. Fat men, and those in whom the heart or blood-vessels are unsound, should avoid them. Protracted indulgence in warm baths is relaxing, and has been esteemed a sign of effeminacy in all ages. Sleepiness, though it will not follow the first immersion in a cold bath, is one of the effects of protracted cold baths; depression of the temperature of the surface becomes dangerous. The risk in cold baths is congestion of the internal organs, as often indicated by the lips getting blue. Extremely cold baths are always dangerous.

For the medical use of baths see BALNEOTHERAPEUTICS. Public Baths. It was not till 1846 that it was deemed advis. able in England, for the "health, comfort, and welfare" of the inhabitants of towns and populous districts, to encourage the establishment therein of baths by the local authority acting through commissioners. A series of statutes, known collectively The Baths and Wash-houses Acts 1846 to 1896," followed By the Public Health Act 1875, the urban authority was declared

as

to be the authority having power to adopt and proceed under the previous acts, and in 1878 provision was for the first time expressly made for the establishment of swimming baths, which might be used during the winter as gymnasia, and by an amending act of 1899, for music or dancing, provided a licence is obtained. By the Local Government Act 1894, it was provided that the parish meeting should be the authority having exclusive power of adopting the Baths and Wash-houses Acts in rural districts, which should, if adopted, be carried into effect by the parish council. Up to 1865 it seems as if only twenty-five boroughs had cared to provide bathing accommodation for their inhabitants. There is no complete information as to the number of authorities who have adopted the acts since 1865, but a return of reproductive undertakings presented to the House of Commons in 1899 shows that 110 local authorities outside the metropolis applied for power to raise loans to provide baths, of whom 48 applied before 1875 and 62 after 1875. In the year 1907 the loans sanctioned for the purpose amounted to £53,026. The revenues of parish councils are so limited that it has not been possible for them to take much advantage of the acts. In the metropolis, by the Local Government Act of 1894, the power of working the act was given to vestries, and by the act of 1899 this power was transferred to the borough councils. There are 35 parishes in London in which the acts have been adopted, all of which except 11 have taken action since 1875. These establishments, according to the return made in 1908, provided 3502 private baths and 104 swimming baths. The maximum charge for a second-class cold bath is id., for a hot bath 2d. In 1904-1905 the number of bathers was 6,342,158, of whom 3,064,998 were bathers in private baths and 3,277,160 bathers in swimming baths. In 1896-1897 the gross total had been only 2,000,000. In cases where the proportion between the sexes has been worked out, it is found that only 18% of the users of private baths, and 10% of the users of swimming baths, are females. In 1898 the School Board was authorized to pay the fees for children using the baths if instruction in swimming were provided, and in 1907-1908 the privilege was used by 1,556,542 children. The cost of this public provision in London -water being supplied by measure-is over £80,000 a year. No account can be given of the numbers using the ponds and lakes in the parks and open spaces, but it is computed that on a hot Sunday 25,000 people bathe in Victoria Park, London, some of the bathers starting as early as four o'clock in the morning. These returns show how great is the increase of the habit of bathing, but they also show how even now the habit is limited to a comparatively small part of the population. People require to be tempted to the use of water, at any rate at the beginning. There are still authorities in London responsible for 800,000 persons who have provided no baths, and those who have made provision have not always done so in a sufficiently liberal and tempting way. The comparison between English great towns and those of the continent is not in favour of the former.

For the literature of baths in earlier periods we may refer to the Architecture of Vitruvius, and to Lucian's Hippias; see art. "Bäder" in Pauly-Wissowa, Realencyclopadie (1896), by A. Mau;" Balneum " in Daremberg and Saglio, Dict. des antiquités; J. Marquardt, Das Privatleben der Römer (1886), pp. 269-297; Becker's Gallus, and the article "Balneae " by Rich, in Dr Smith's Dictionary of Greek and Roman Antiquities (rev. ed. 1890); also the bibliography to HYDROPATHY.

BATHURST, EARLS. ALLEN BATHURST, 1st Earl Bathurst (1684-1775), was the eldest son of Sir Benjamin Bathurst (d. 1704), by his wife, Frances (d. 1727), daughter of Sir Allen Apsley of Apsley, Sussex, and belonged to a family which is said to have settled in Sussex before the Norman Conquest. He was educated at Trinity College, Oxford, and became member of parliament for Cirencester in May 1705, retaining his scat until December 1711, when he was created Baron Bathurst of Battlesden, Bedfordshire. As a zealous Tory he defended Atterbury, bishop of Rochester, and in the House of Lords was an opponent of Sir Robert Walpole. After Walpole left office in 1742 he was made a privy councillor, and in August 1772 was created Earl

Bathurst, having previously received a pension of £2000 a year chargeable upon the Irish revenues. He died on the 16th of September 1775, and was buried in Cirencester church. In July 1704 Bathurst married his cousin, Catherine (d. 1768), daughter of Sir Peter Apsley, by whom he had four sons and five daughters. The earl associated with the poets and scholars of the time. Pope, Swift, Prior, Sterne, and Congreve were among his friends. He is described in Sterne's Letters to Eliza; was the subject of a graceful reference on the part of Burke speaking in the House of Commons; and the letters which passed between him and Pope are published in Pope's Works, vol. viii. (London, 1872).

HENRY, 2nd Earl Bathurst (1714-1794), was the eldest surviving son of the 1st carl. Educated at Balliol College, Oxford, he was called to the bar, and became a K.C. in 1745In April 1735 he had been elected member of parliament for Cirencester, and was rewarded for his opposition to the government by being made solicitor-general and then attorney-general to Frederick, prince of Wales. Resigning his seat in parliament in April 1754 he was made a judge of the court of common pleas in the following month, and became lord high chancellor in January 1771, when he was raised to the peerage as Baron Apsley. Having become Earl Bathurst by his father's death in September 1775, he resigned his office somewhat unwillingly in July 1778 to enable Thurlow to join the cabinet of Lord North. In November 1779 he was appointed lord president of the council, and left office with North in March 1783. He died at Oakley Grove near Cirencester on the 6th of August 1794. Bathurst was twice married, and left two sons and four daughters. He was a weak lord chancellor, but appears to have been just and fair in his distribution of patronage.

HENRY, 3rd Earl Bathurst (1762-1834), the elder son of the second earl, was born on the 22nd of May 1762. In April 1789 he married Georgiana (d. 1841), daughter of Lord George Henry Lennox, and was member of parliament for Cirencester from 1783 until he succeeded to the earldom in August 1794. Owing mainly to his friendship with William Pitt, he was a lord of the admiralty from 1783 to 1789; a lord of the treasury from 1789 to 1791; and commissioner of the board of control from 1793 to 1802. Returning to office with Pitt in May 1804 he became master of the mint, and was president of the Board of Trade and master of the mint during the ministries of the duke of Portland and Spencer Perceval, only vacating these posts in June 1812 to become secretary for war and the colonies under the earl of Liverpool. For two months during the year 1809 he was in charge of the foreign office. He was secretary for war and the colonies until Liverpool resigned in April 1827; and deserves some credit for improving the conduct of the Peninsular War, while it was his duty to defend the government concerning its treatment of Napoleon Bonaparte. Bathurst's official position caused his name to be mentioned frequently during the agitation. for the abolition of slavery, and with regard to this traffic he seems to have been animated by a humane spirit. He was lord president of the council in the government of the duke of Wellington from 1828 to 1830, and favoured the removal of the disabilities of Roman Catholics, but was a sturdy opponent of the reform bill of 1832. The earl, who had four sons and two daughters, died on the 27th of July 1834. Bathurst was made a knight of the Garter in 1817, and held several lucrative sinecures.

His eldest son, HENRY GEORGE, 4th Earl Bathurst (17001866), was member of parliament for Cirencester from 1812 to 1834. He died unmarried on the 25th of May 1866, and was succeeded in the title by his brother, WILLIAM LENNOX, 5th Earl Bathurst (1791-1878), member of parliament for Weobley from 1812 to 1816, and clerk of the privy council from 1827 to 1860, who died unmarried on the 24th of February 1878.

ALLEN ALEXANDER, 6th Earl Bathurst (1832-1892), was the son of Thomas Seymour Bathurst, and grandson of the 3rd earl He was member of parliament for Cirencester from 1857 until he became Earl Bathurst in February 1878, and died on the 2nd of August 1892, when his eldest son, SEYMOUR HENRY (b. 1864), became 7th Earl Bathurst.

BATHVILLITE, a naturally occurring organic substance. It is an amorphous, opaque, and very friable material of fawnbrown colour, filling cavities in the torbanite or Boghead coal of Bathville, Scotland. It has a specific gravity of 1.01, and is insoluble in benzene.

BATHYBIUS (Balís, deep, and Bios, life), a slimy substance at one time supposed to exist in great masses in the depths of the ocean and to consist of undifferentiated protoplasm. Regarding it as an organism which represented the simplest form of life, Huxley about 1868 named it Bathybius Haeckelii. But investigations carried out in connexion with the "Challenger " expedition indicated that it was an artificial product, composed of a flocculent precipitate of gypsum thrown down from seawater by alcohol, and the hypothesis of its organic character was abandoned by most biologists, Huxley included.

BATHYCLES, an Ionian sculptor of Magnesia, was commissioned by the Spartans to make a marble throne for the statue of Apollo at Amyclae, about 550 B.C. Pausanias (iii. 18) gives us a detailed description of this monument, which is of the greatest value to us, showing the character of Ionic art at the time. It was adorned with scenes from mythology in relief and supporting figures in the round.

For a reconstruction, see Furtwängler, Meisterwerke der griech. Plastik, p. 706.

BATLEY, a municipal borough in the West Riding of Yorkshire, England, within the parliamentary borough of Dewsbury, 8 m. S.S.W. of Leeds, on the Great Northern, London & North Western, and Lancashire & Yorkshire railways. Pop. (1900) 30,321. Area 2039 acres. The church of All Saints is mainly Perpendicular, and contains some fine woodwork, mostly of the 17th century, and some good memorial tombs. The market square contains an excellent group of modern buildings, including the town hall, public library, post office and others. The town is a centre of the heavy woollen trade, and has extensive manufactures of army cloths, pilot cloths, druggets, flushings, &c. The working up of old material as" shoddy "is largely carried on. There are also iron foundries, manufactures of machinery, and stone quarries. The town lies on the south-west Yorkshire coalfield, and there are a number of collieries in the district. The borough is governed by a mayor, six aldermen, and eighteen councillors.

BATON (Fr. baton, baston, from Late Lat. basto, a stick or staff), the truncheon carried by a field marshal as a sign of authority, by a police constable, &c.; in music, the stick with which the conductor of an orchestra beats time; in heraldry, the fourth part of a bend, frequently broken off short at the ends so as to be shaped like a rod; in English coats of arms, only as a mark of illegitimacy, the "baton sinister."

BATONI, POMPEO GIROLAMO (1708-1787), Italian painter, was born at Lucca. He was regarded in Italy as a great painter in the 18th century, and unquestionably did much to rescue the art from the intense mannerism into which it had fallen during the preceding century. His paintings, however, are not of the highest order of merit, though they are generally graceful, well designed, and harmoniously coloured. His best production is

BATON ROUGE, the capital of Louisiana, U.S.A., and of East Baton Rouge parish, on the E. bank of the Mississippi river, about 70 m. N.W. of New Orleans. Pop. (1890) 10,478; (1900) 11,269, of whom 6596 were of negro descent; (1910 census) 14,897. It is served by the Yazoo & Mississippi Valley railway and by the Louisiana Railway & Navigation Company; and the Texas & Pacific enters Port Allen, just across the river. The city lies on the river bluff, secure against the highest floods. Old houses in the Spanish style give quaintness to its appearance. The state capitol was built in 1880-1882, replacing another burned in 1862. At Baton Rouge is the State University and Agricultural and Mechanical College (1860), of which the Audubon Sugar School, "for the highest scientific training in the growing of sugar cane and in the technology of sugar manufacture," is an important and 'distinctive feature. The university grew out of the Louisiana State Seminary of Learning and Military Academy, founded in 1855 near Alexandria and opened in 1860 under the charge of W. T. Sherman. In 1869 the institution was removed to Baton Rouge, and in 1877 it was united with the Agricultural and Mechanical College, established in 1873 and in 1874 opened at New Orleans. The campus of the university is the former barracks of the Baton Rouge garrison, occupied by the college since 1886 and transferred to it by the Federal government in 1902. The enrolment of the university in 1907-1908 was 636. Other important institutions at Baton Rouge are a State Agricultural Experiment Station, asylums and schools for the deaf and dumb, for the blind, and for orphans, and the state penitentiary. The surrounding bluff and alluvial country is very rich. Sugar and cotton plantations and subtropic fruit orchards occupy the front-lands on the river. The manufactures include lumber and cotton seed products, and sugar. The value of the city's factory products increased from $717,368 in 1900 to $1,383,061 in 1905 or 92.8%. The city is governed under a charter granted by the legislature in 1898. This charter is peculiar in that it gives to the city council the power to elect various administrative boards-of police, finance, &c.—from which the legislative council of most cities is separated.

Baton Rouge was one of the earliest French settlements in the state. As a part of West Florida, it passed into the hands of the British in 1763, and in 1779 was captured by Bernardo Galvez, the Spanish governor of Louisiana. The town was incorporated in 1817. In 1849 it was made the state capital, remaining so until 1862, when Shreveport became the Confederate state capital. In 1864 the Unionists made New Orleans the seat of government. The Secession Ordinance of Louisiana was passed on the 26th of January 1861 by a convention that met at Baton Rouge. On the 2nd of May 1862 the city was captured by the forces of the United States under Col. Benjamin H. Grierson (b. 1826), who had led raiders thither from Tennessee; on the 12th of May it was formally occupied by troops from New Orleans, and was successfully defended by Brig.-Gen. Thomas Williams (1815-1862) against an attack by Confederate forces under General John C. Breckinridge on the 5th of August 1862; Gen. Williams, however, was killed during the attack. Baton Rouge was soon abandoned for a month, was then reoccupied, and was held throughout the rest of the war. It became the state capital again in 1882, in accordance with the state constitution of 1879. For several years after 1840 Zachary Taylor made his home on a plantation ncar Baton Rouge.

BATRACHIA. The arguments adduced by T. H. Huxley, in his article on this subject in the ninth edition of the Encyclopaedia Britannica, for applying the name Amphibia to those lung-breathing, pentadactyle vertebrates which had been first severed from the Linnaean Amphibia by Alexandre Brongniart, under the name of Batrachia, have not met with universal acceptance. Although much used in text-books and anatomical works in Great Britain and in Germany, the former name has been discarded in favour of the latter by the principal authors

on systematic herpetology, such as W. Peters, A. Günther and E. D. Cope, and their lead is followed in the present article. Bearing in mind that Linnaeus, in his use of the name Amphibia, was not alluding to the gill-breathing and air-breathing periods through which most frogs and newts pass in the course of their existence, but only wished to convey the fact that many of the constituents of the group resort to both land and water (e.g. crocodiles), it seems hard to admit that the term may be thus diverted from its original signification, especially when such a change results in discarding the name expressly proposed by Brongniart to denote the association which has ever since been universally adopted either as an order, a sub-class or a class. Many authors who have devoted special attention to questions of nomenclature therefore think Reptilia and Batrachia the correct names of the two great classes into which the Linnaean Amphibia have been divided, and consider that the latter term should be reserved for the use of those who, like that great authority, the late Professor Peters, down to the time of his death in 1883, would persist in regarding reptiles and batrachians as mere sub-classes (1). However extraordinary it may appear, especially to those who bring the living forms only into focus, that opposition should still be made to Huxley's primary division of the vertebrates other than mammals into Sauropsida (birds and reptiles) and Ichthyopsida (batrachians and fishes), it is certain that recent discoveries in palaeontology have reduced the gap between batrachians and reptiles to such a minimum as to cause the greatest embarrassment in the attempt to draw a satisfactory line of separation between the two; on the other hand the hiatus between fishes and batrachians remains as wide as it was at the time Huxley's article Amphibia (Encyclopaedia Britannica, 9th ed.) was written.

The chief character which distinguishes the Batrachians from the reptiles, leaving aside the metamorphoses, lies in the arrangement of the bones of the palate, where a large parasphenoid extends forwards as far or nearly as far as the vomers and widely separates the pterygoids. The bones which bear the two occipital condyles have given rise to much discussion, and the definition given by Huxley in the previous edition-" two occipital condyles, the basi-occipital region of the skull either very incompletely or not at all ossified "-requires revision. Some authors have held that the bone on which the occipital condyles have been found most developed in some labyrinthodonts (2) represents a large basi-occipital bearing two knobs for the articulation with the first vertebra, whilst the skull of the batrachians of the present day has lost the basi-occipital, and the condyles are furnished by the exoccipitals. On the other hand, some reptiles have the occipital condyle divided into two and produced either by the basi-occipital or by the exoccipitals. But the recent find of a well preserved skull of a labyrinthodont (Capilosaurus stantonensis) from the Trias of Staffordshire has enabled A. S. Woodward (3) to show that, in that form at any rate, the condyles are really exoccipital, although they are separated by a narrow basi-occipital. It is therefore very probable that the authors quoted in (2) were mistaken in their identification of the elements at the base of the foramen magnum. The fact remains, however, that some if not all of the stegocephalous batrachians have an ossified basi-occipital. As a result of his researches on the anomodont reptiles and the Stegocephalia (4), as the extinct order that includes the well known labyrinthodonts is now called, we have had the proposal by H. G. Seeley (5) to place the latter with the reptiles instead of with the batrachians, and H. Gadow, in his most recent classification (6), places some of them among the reptiles, others being left with the batrachians; whilst H. Credner, basing his views on the discovery by him of various annectent forms between the Stegocephalia and the Rhynchocephalian reptiles, has proposed a class, Eotetrapoda, to include these forms, ancestors of the batrachians proper on the one hand, of the reptiles proper on the other. Yet, that the Stegocephalia, notwithstanding their great affinity to the reptiles, ought to be included in the batrachians as commonly understood, seems sufficiently obvious from the mere fact of their passing through

a branchiate condition, i.e. undergoing metamorphosis (7). The outcome of our present knowledge points to the Stegocephalia, probably themselves derived from the Crossopterygian fishes (8), having yielded on the one hand the true batrachians (retrogressive series), with which they are to a certain extent connected through the Caudata and the Apoda, on the other hand the reptiles (progressive series), through the Rhynchocephalians and the Anomodonts, the latter being believed, on very suggestive evidence, to lead to the mammals (9).

pm

The division of the class Amphibia or Batrachia into four orders, as carried out by Huxley, is maintained, with, however, a change of names: Stegocephalia, for the assemblage of minor groups that cluster round the Labyrinthodonta of R. Owen, which name is restricted to the forms for which it was originally intended; Peromela, Urodela, Anura, are changed to Apoda, Caudata, Ecaudata, for the reason that (unless obviously misleading, which is not the case in the present instance) the first proposed name should supersede all others for higher groups as well as for genera and species, and the latter set have the benefit of the law of priority. In the first subdivision of the batrachians into two families by C. Duméril in 1806 (Zool. Anal. pp. 90-94) these are termed Anoures " and "Urodeles

in French,

FIG. 1.

j

st

- Upper view of Archegosaurus Decheni. (Outlines after Gredner.)

poral.

sq, Squamosal. plo, Postorbital. qi. Quadratojugal.

Ecaudati and Caudati in pm, Praemaxilla. st, SupratemLatin. When Duméril's n, Nasal. pupil, M. Oppel, in 1811 m, Maxilla. Lachrymal. (Ordn. Rept. p. 72), added pf. Praefrontal. the Caecilians, he named f. Frontal. the three groups Apoda, j, Jugal. Ecaudata and Caudata. The ptf, Postfrontal. Latin form being the only P. Parietal. q, Quadrate. one entitled to recognition in zoological nomenclature, it follows that the last-mentioned names should be adopted for the three orders into which recent batrachians are divided.

o, Occipital. pt. Post-temporal.

I. STEGOCEPHALIA (10).-Tailed, lacertiform or serpentiform batrachians, with the temporal region of the skull roofed over by postorbital, squamosal, and supratemporal plates similar to the same bones in Crossopterygian fishes, and likewise with paired dermal bones (occipitals and post-temporals) behind the parietals and supratemporals. A parietal foramen; scales or bony scutes frequently present, especially on the ventral region, which is further protected by three large bony plates-interclavicle and clavicles, the latter in addition to cleithra.

Extinct, ranging from the Upper Devonian to the Trias. Our knowledge of Devonian forms is still extremely meagre, the only certain proof of the existence of pentadactyle vertebrates at that period resting on the footprints discovered in Pennsylvania and described by O. C. Marsh (11) as Tinopus antiquus. Sundry remains from Belgium, as to the identification of which doubts are still entertained, have been regarded by M. Lohest (12) as evidence of these batrachians in the Devonian. Over 200 species are now distinguished, from the Carboniferous of Europe and North America, the Permian of Spitsbergen, Europe, North America and South Africa, and the Trias of Europe, America, South Africa, India and Australia. The forms of batrachians with which we are acquainted time from a notochordal condition with segmented centra similar show the vertebral column to have been evolved in the course of to that of early bony ganoid fishes (e.g. Caturus Eurycormas), to biconcave centra, and finally to the socket-and-ball condition that prevails at the present day. However, owing to the evolution of the vertebral column in various directions, and to the inconstant state of things in certain annectent groups, it is not possible, it seems, to apply the vertebral characters to taxonomy with that rigidity which E. D. Cope and some other recent authors have attempted to enforce.

This is particularly evident in the case of the Stegocephalians; and recent batrachians, tailed and tailless, show the mode of articulation of the vertebrae, whether amphicoelous, opisthocoelous or procoelous, to be of but secondary systematic importance in dealing with these lowly vertebrates. The following division of the Stegocephalians into five sub-orders is therefore open to serious criticism; but it seems on the whole the most natural to adopt in the light of our present knowledge.

A. Rhachitomi, (figs. 1, 2), in which the spinal cord rests on the notochord, which persists uninterrupted and is surrounded by three bony elements in addition to the neural arch: a so-called pleurocentrum on each side, which appears to represent the centrum proper of reptiles and mammals, and an intercentrum or hypocentrum below, which may extend to the neural arch, and probably answers to the hypapophysis, as it is produced into chevrons in the caudal region. Mostly large forms, of Carboniferous and Permian age, with a more or less complex infolding of the walls of the teeth. Families: ARCHEGOSAURIDAE, ERYOPIDAE, TRIMERORHACHIDAE, DISSORHOPHIDAE. The last is remarkable for an extraordinary endo- and exo-skeletal carapace, Dissorhophus being described by Cope (13) as a batrachian armadillo."

B. Embolomeri, with the centra and intercentra equally developed disks, of which there are thus two to each neural arch; these disks perforated in the middle for the passage of the notochord. This type may be directly derived from the preceding, with which it appears to be connected by the genus Diplospondylus. Fam.: CRICOTIDAE, Permian.

C. Labyrinthodonta, with simple biconcave vertebral disks, very slightly pierced by a remnant of the notochord and supporting the loosely articulated neural arch. This condition is derived from

arch rests.

D. Microsauria, nearest the reptiles, with persistent notochord completely surrounded by constricted cylinders on which the neural Teeth hollow, with simple or only slightly folded walls. Mostly of small size and abundant in the Carboniferous and Lower Permian. Families: UROCORDYLIDAE, LIMNER PETIDAE, HYLONOMIDAE (fig. 3), MICROBRACHIDAE, DOLICHOSOMATIDAE; the latter serpentiform, apodal.

E. Branchiosauria, nearest to the true batrachians; with persistent non-constricted notochord, surrounded by barrel-shaped, bony cylinders formed by the neural arch above and a pair of intercentra below, both these elements taking an equal share in the formation of a transverse process on each side for the support of the rib. This plan of structure, apparently evolved out of the rhachitomous type by suppression of the pleurocentra and the downward extension of the neural arch, leads to that characteristic of frogs in which, as development shows, the vertebra is formed wholly or for the greater part by the neural arch (14). Small forms from the Upper Carboniferous and Permian formations. A single family: BRANCHIOII. APODA (15).-No limbs. Tail vestigial or absent. Frontal bones distinct from parietals; palatines fused with maxillaries. Male with an intromittent copulatory organ. Degraded, worm-like batrachians of still obscure affinities, inhabiting tropical Africa, south-eastern Asia and tropical America. Thirty-three species are known. No fossils have yet been discovered. It has been attempted of late to do away with this order altogether and to make the Caecilians merely a family of the Urodeles. This view has originated

SAURIDAE.

out of the very remarkable superficial resemblance between the Ichthyophis-larva and the Amphiuma. Cope (16) regarded the Apoda as the extremes of a line of degeneration from the Salamanders, with Amphiuma as one of the annectent forms. In the opinion of P. and F. Sarasin (17), whose great work on the development of Ichthyophis is one of the most important recent contributions to our knowledge of the batrachians, Amphiuma is a sort of neotenic Caecilian, a larval form become sexually mature while retaining the branchial respiration. If the absence of limbs and the reduction of the tail were the only characteristic of the group, there would be, of course, no objection to unite the Caecilians with the Urodeles; but, to say nothing of the scales, present in many genera of Apodals and absent in all Caudates, which have been shown

A

by H. Credner to be identical in structure with those of Stegocephalians, FIG. 3.-A, Dorsal vertebra of Hylonothe Caecilian skull pre- mus (side view and front view). B, Dorsal sents features which are vertebra of Branchiosaurus (side view and not shared by any of front view). n, Neural canal; ch, chorda.

(After Credner.)

the tailed batrachians. G. M. Winslow (18), who has made a study of the chondrocranium of Ichthyophis, concludes that its condition could not have been derived from a Urodele form, but points to some more primitive ancestor. That this ancestor was nearly related to, if not one of, the Stegocephalians, future discovery will in all probability

show.

III. CAUDATA (19).-Tailed batrachians, with the frontals distinct from the parictals and the palatines from the maxillary. Some of the forms breathe by gills throughout their existence, and were formerly regarded as establishing a passage from the fishes to the air-breathing batrachians. They are now considered as arrested larvae descended from the latter. One of the most startling discoveries of the decade 1890-1900 was the fact that a number of forms are devoid of both gills and lungs, and breathe merely by the skin and the buccal mucose membrane (20). Three blind cave-forms are known: one terrestrial-Typhlotriton, from North America, and two perennibranchiate-Proteus in Europe and Typhlomolge in North America.

This order contains about 150 species, referred to five families: HYLAEOBATRACHIDAE, SALAMANDRIDAE, AMPHIUMIDAE, ProteiDAE, SIRENIDAE.

Fossil remains are few in the Upper Eocene and Miocene of Europe and the Upper Cretaceous of North America. The oldest Urodele known is Hylaeobatrachus Dollo (21) from the Lower Wealden of Belgium. At present this order is confined to the northern hemisphere, with the exception of two Spelerpes from the Andes of Ecuador and Peru, and a Plethodon from Argentina.

IV. ECAUDATA (22).-Frogs and toads. Four limbs and no tail. Radius confluent with ulna, and tibia with fibula; tarsus (astragalus and calcaneum) elongate, forming an additional segment in the hind limb. Caudal vertebrae fused into a urostyle or coccyx. Frontal bones confluent with parietals.

This order embraces about 1300 species, of which some 40 are fossil, divided into two sub-orders and sixteen families:A.

Aglossa,-Eustachian tubes united into a single ostium pharyngeum; no tongue. DACTYLETHRIDAE, PIPIDAE,

B. Phaneroglossa,-Eustachian tubes separated; tongue present. DiscOGLOSSIDAE, PELOBATIDAE, HEMIPHRACTIDAE, AMPHIGNATHODONTIDAE, HYLIDAE, BUFONIDAE, DENDROPHRYNISCIDAE, CYSTIGNATHIDAE, DYSCOPHIDAE, GENYOPHRYNIDAE, ENGYSTOMA

TIDAE, CERATOBATRACHIDAE, RANIDAE, DENDROBATIDAE. The Phaneroglossa are divided into two groups; Arcifera and Firmisternia, representing two stages of evolution. The family characters are mainly derived from the dilatation or non-dilatation of the sacral diapophyses, and the presence of teeth in one or both jaws, or their absence. The Discoglossidae are noteworthy for the presence of short ribs to some of the vertebrae, and in some other points also they approach the tailed batrachians; they may be safely regarded as, on the whole, the most generalized of known Ecaudata. Distinct ribs are present at an early age in the Aglossa, as discovered by W. G. Ridewood (23). The recent addition of a third genus of Aglossa, Hymenochirus (24) from tropical Africa, combining characters of Pipa and Xenopus, has removed every doubt as to the real affinity which connects these genera. Hymenochirus is further remarkable for the presence of only six distinct pieces in the vertebral