[1] The figure represents four strigils, in which the hollow for
collecting the oil or perspiration from the body may be observed.
There is also a small ampulla or vessel containing oil, meant to keep
the strigils smooth, and a small flat patera or drinking vessel out
of which it was customary to drink after the bathing was finished.
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 seat 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 L2000 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 earl. Educated at Balliol College, Oxford, he was called to the
bar, and became a K.C. in 1745. In 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 1782. 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 (1790-1866), 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.
BATHURST, a city of Bathurst county, New South Wales, Australia, 144 m.
by rail W.N.W. of Sydney on the Great Western railway. Pop. (1901) 9223.
It is situated on the south bank of the Macquarie river, at an elevation
of 2153 ft., in a fertile undulating plain on the west side of the Blue
Mountains. Bathurst has broad streets,, crossing one another at right
angles, with a handsome park in the centre of the town, while many of
the public buildings, specially the town hall, government buildings, and
Anglican and Roman Catholic cathedrals, are noteworthy. Bathurst is the
centre of the chief wheat-growing district of New South Wales, while
gold, copper and silver are extensively mined in its vicinity. There are
railway works, coach factories, tanneries, breweries, flour-mills and
manufactures of boots and shoes and other commodities. The town was
founded in 1815 by Governor Macquarie, taking its name from the 3rd Earl
Bathurst, then secretary of state for the colonies, and it has been a
municipality since 1862.
BATHVILLITE, a naturally occurring organic substance. It is an
amorphous, opaque, and very friable material of fawn-brown 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 ([Greek: bathis], deep, and [Greek: 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 sea-water 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 Furtwangler, _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 thought to be his group of "Peace and War." Batoni painted
an unusual number of pictures, and was also celebrated for his
portraits.
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 Alien, 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 sub-tropic 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
and 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 near 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. Gunther 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 (_Capitosaurus 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).
[Illustration: FIG. 1.--Upper view of _Archegosaurus Decheni_.
(Outlines after Gredner.)
pm, Praemaxilla. st, Supratemporal.
n, Nasal. sq, Squamosal.
m, Maxilla. pto, Postorbital.
l, Lachrymal. qj, Quadrato-jugal.
pf, Praefrontal. o, Occipital.
f, Frontal. pt, Post-temporal.
j, Jugal. q, Quadrate.
ptf, Postfrontal.
p, Parietal.]
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. Dumeril in 1806 (_Zool. Anal_. pp.
90-94) these are termed "Anoures" and "Urodeles" in French, _Ecaudati_
and _Caudati_ in Latin. When Dumeril's pupil, M. Oppel, in 1811 (_Ordn.
Rept_. p. 72), added the Caecilians, he named the three groups _Apoda_,
_Ecaudata_ and _Caudata_. The Latin form being the only 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.
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 show the vertebral column to have been
evolved in the course of time from a notochordal condition with
segmented centra similar to that of early bony ganoid fishes (e.g.
_Caturus_, _Eurycormus_), 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.
[Illustration: FIG 2.--A, Dorsal vertebrae. B, Caudal vertebra of
_Archegosaurus_. na, Neural arch; ch, chorda; pl, pleurocentrum; ic,
intercentrum.
(Outline after Jaekel.)]
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 that
of the _Rhachitomi_, as shown by the structure of the vertebral column
in young specimens. Mostly large forms from the Trias (a few Permian),
with true labyrinthic dentition. Families: LABYRINTHODONTIDAE,
ANTHRACOSAURIDAE, DENDRERPETIDAE, NYRANIIDAE.
D. Microsauria, nearest the reptiles, with persistent notochord
completely surrounded by constricted cylinders on which the neural
arch rests. Teeth hollow, with simple or only slightly folded walls.
Mostly of small size and abundant in the Carboniferous and Lower
Permian. Families: UROCORDYLIDAE, LIMNERPETIDAE, 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: BRANCHIOSAURIDAE.
[Illustration: FIG. 3.--A, Dorsal vertebra of _Hylonomus_ (side view
and front view). B, Dorsal vertebra of _Branchiosaurus_ (side view and
front view). n, Neural canal; ch, chorda.
(After Credner.)]
II. 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 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 by
H. Credner to be identical in structure with those of Stegocephalians,
the Caecilian skull presents features which are not shared by any of
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 parietals 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, ENGYSTOMATIDAE, 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 column,
which is thus the most abbreviated among all the vertebrata.
Frogs and toads occur wherever insect food is procurable, and their
distribution is a world-wide one, with the exception of many islands.
Thus New Caledonia, which has a rich and quite special lizard-fauna,
has no batrachians of its own, although the Australian _Hyla aurea_
has been introduced with success. New Zealand possesses only one
species (_Liopelma hochstetteri_), which appears to be rare and
restricted to the North Island. The forest regions of southern Asia,
Africa and South America are particularly rich in species.
According to our present knowledge, the Ecaudata can be traced about
as far back in time as the Caudata. An unmistakable batrachian of this
order, referred by its describer to _Palaeobatrachus_, a determination
which is only provisional, has been discovered in the Kimmeridgian of
the Sierra del Montsech, Catalonia (25), in a therefore somewhat older
formation than the Wealden Caudata _Hylaeobatrachus_.
Apart from a few unsatisfactory remains from the Eocene of Wyoming,
fossil tailless batrachians are otherwise only known from the
Oligocene, Miocene and Pliocene of Europe and India. These forms
differ very little from those that live at the present day in the same
part of the world, and some of the genera (_Discoglossus, Bufo,
Oxyglossus, Rana_) are even identical. _Palaeobatrachus_ (26), of
which a number of species represented by skeletons of the perfect form
and of the tadpole have been described from Miocene beds in Germany,
Bohemia and France, seems to be referable to the _Pelobatidae_; this
genus has been considered as possibly one of the Aglossa, but the
absence of ribs in the larvae speaks against such an association.
Numerous additions have been made to our knowledge of the development
and nursing habits, which are extremely varied, some forms dispensing
with or hurrying through the metamorphoses and hopping out of the egg
in the perfect condition (27).
_Skeleton._--In the earliest forms of this order, the Stegocephalia,
we meet with considerable variety in the constitution of the
vertebrae, and these modifications have been used for their
classification. All agree, however, in having each vertebra formed of
at least two pieces, the suture between which persists throughout
life. In this they differ from the three orders which have living
representatives. Even the inferior arches or chevrons of the tail of
salamanders are continuously ossified with the centra. As a matter of
fact, these vertebrae have no centra proper, that part which should
correspond with the centrum being formed, as a study of the
development has shown (H. Gadow, 14), by the meeting and subsequent
complete co-ossification of the two chief dorsal and ventral pairs of
elements (tail-vertebrae of Caudata), or entirely by the pair of
dorsal elements. In the Ecaudata, the vertebrae of the trunk are
formed on two different plans. In some the notochord remains for a
long time exposed along the ventral surface, and, owing to the absence
of cartilaginous formation around it, disappears without ever becoming
invested otherwise than by a thin elastic membrane; it can be easily
stripped off below the vertebrae in larval specimens on the point of
metamorphosing. This has been termed the _epichordal_ type. In others,
which represent the _perichordal_ type, the greater share of the
formation of the whole vertebra falls to the (paired) dorsal
cartilage, but there is in addition a narrow ventral or hypochordal
cartilage which fuses with the dorsal or becomes connected with it by
calcified tissue; the notochord is thus completely surrounded by a
thick sheath in tadpoles with imperfectly developed limbs. This mode
of formation of both the arch and the greater part or whole of the
so-called centrum from the same cartilage explains why there is never
a neuro-central suture in these batrachians.
During segmentation of the dorsal cartilages mentioned above, which
send out the transverse processes of diapophyses, there appears
between each two centra an intervertebral cartilage, out of which the
articulating condyle of the centrum is formed, and becomes attached
either to the vertebra anterior (precoelous type) or posterior
(opisthocoelous type) to it, if not remaining as an independent,
intervertebral, ossified sphere, as we sometimes find in specimens of
_Pelobatidae_.
[Illustration: FIG. 4.--The first two vertebrae of _Necturus_. Vt^1,
Atlas; Vt^2, second vertebrae; a, intercondyloid process of the atlas;
b, the articular surfaces for the occipital condyles. The ribs of the
second vertebra are not represented. A, Dorsal; B, ventral; C, lateral
view. ]
In the Caudata and Apoda, cartilage often persists between the
vertebrae; this cartilage may become imperfectly separated into a
cup-and-ball portion, the cup belonging to the posterior end of the
vertebra. In such cases the distinction between amphicoelous and
opisthocoelous vertebrae rests merely on a question of ossification,
and has occasionally given rise to misunderstandings in the use of
these terms.
[Illustration: FIG. 5.--_Necturus_. Posterior (A) and ventral (B)
views of the sacral vertebrae (S.V.); S.R.^1, S.R.^2, sacral ribs; Il,
ilium; Is, ischium.]
[Illustration: FIG. 6.-Vertebral column of _Hymenochtrus_ (ventral
view).]
Amphicoelous (bi-concave) vertebrae are found in the Apoda and in some
of the Caudata; opisthocoelous (convexo-concave) vertebrae in the
higher Caudata and in the lower Ecaudata; whilst the great majority of
the Ecaudata have procoelous (concavo-convex) vertebrae.
[Illustration: FIG. 7.--Chondrocranium of _Rana esculenta_--ventral
aspect.
rp, The rhinal process.
pnl, The praenasal processes.
an, The alinasal processes, shown by the removal of part of the
floor of the left nasal chamber.
AO., The antorbital process.
pd, The pedicle of the suspensorium continued into cv, the
ventral crus of the suspensorium.
cd, Its dorsal crus.
tt, The tegmen tympani.
SE, The sphen-ethmoid.
EO., The exoccipitals.
Qu.J., The quadratojugal.
II. V. VI. Foramina by which the optic, trigeminal and abortio dura,
and abducens nerves leave the skull.]
All living batrachians, and some of the Stegocephalia, have transverse
processes on the vertebrae that succeed the atlas (fig. 4), some of
which, in the Caudata, are divided into a dorsal and a ventral
portion. Ribs are present in the lower Ecaudata (_Discoglossidae_ and
larval Aglossa), but they are never connected with a sternum. It is in
fact doubtful whether the so-called sternum of batrachians, in most
cases a mere plate of cartilage, has been correctly identified as
such. When limbs are present, one vertebra, rarely two (fig. 5) or
three, are distinguished as sacral, giving attachment to the ilia. In
the Ecaudata, the form of the transverse processes of the sacral
vertebra varies very considerably, and has afforded important
characters to the systematist. In accordance with the saltatorial
habits of the members of this order, the vertebrae, which number from
40 to 60 in the Caudata, to upwards of 200 in the Apoda, have become
reduced to 10 as the normal number, viz., eight praecaudal, one sacral
and an elongate coccyx or urostyle, formed by coalescence of at least
two vertebrae. In some genera this coccyx is fused with the ninth
vertebra, and contributes to the sacrum, whilst in a few others the
number of segments is still further reduced by the co-ossification of
one or two vertebrae preceding that corresponding to the normal sacral
and by the fusion of the two first vertebrae, the extreme of reduction
being found in the genus _Hymenochirus_, the vertebral column of which
is figured here (fig 6.)
[Illustration: FIG. 8.--The skull of _Ichthyophis glutinosus_ A,
Dorsal; B, ventral; C, lateral view. The letters have the same
signification as below.]
As stated above in the definition of the order, the Stegocephalia have
retained most of the cranial bones which are to be found in the
Crossopterygian fishes, and it is worthy of note that the bones termed
post-temporals may give attachment to a further bone so prolonged
backwards as to suggest the probability of the skull being connected
with the shoulder-girdle, as in most teleostome fishes. This
supposition is supported by a specimen from the Lower Permian of
Autun, determined as _Actinodon frossardi_, acquired in 1902 by the
British Museum, which shows a bone, similar to the so-called "epiotic
cornu" of the microsaurians, _Ceraterpeton_ and _Scincosaurus_, to
have the relations of the supra-cleithrum of fishes, thus confirming a
suggestion made by C.W. Andrews (28). As in fishes also, the sensory
canal system must have been highly developed on the skulls of many
labyrinthodonts, and the impressions left by these canals have been
utilized by morphologists for homologizing the various elements of the
cranial roof with those of Crossopterygians. The pineal foramen, in
the parietal bones, is as constantly present as it is absent in the
other orders. Although not strictly forming part of the skull,
allusion should be made here to the ring of sclerotic plates which has
been found in many of the Stegocephalia, and which is only found
elsewhere in a few Crossopterygian fishes as well as in many reptiles
and birds.
In the orders which are still represented at the present day, the
bones of the skull are reduced in number and the "primordial skull,"
or chondrocranium (fig. 7), remains to a greater or less extent
unossified, even in the adult. Huxley's figures of the skull of a
caccilian (_Ichthyophis glutinosus_), fig. 8, of a perennibranchiate
urodele (_Necturus maculosus = Menobranchus lateralis_), fig. 9, and
of a frog (_Rana esculenta_), fig. 10, are here given for comparison.
The skull, in the _Apoda_, is remarkably solid and compact, and it
possesses a postorbital or postfrontal bone (marked 1 in the figure)
which does not exist in any of the other living batrachians. The
squamosal bone is large and either in contact with the frontals and
parietals or separated from them by a vacuity; the orbit is sometimes
roofed over by bone. The presence, in some genera, of a second row of
mandibular teeth seems to indicate the former existence of a splenial
element, such as exists in _Siren_ among the Caudata and apparently in
the labyrinthodonts.
In the Caudata, the frontals remain likewise distinct from the
parietals, whilst in the Ecaudata the two elements are fused into one,
and in a few forms (Aglossa, some _Pelobalidae_) the paired condition
of these bones has disappeared in the adult. Prefrontal bones are
present in the _Salamandridae_ and _Amphiumidae_, but absent (or fused
with the nasals) in the other Caudata and in the Ecaudata. In most of
the former the palatines fuse with the vomers, whilst they remain
distinct, unless entirely lost, in the latter. The vomer is single, or
absent, in the Aglossa. In the lower jaw of most of the Ecaudata the
symphysial cartilages ossify separately from the dentary bones,
forming the so-called mento-meckelian bones; but these symphysial
bones, so distinct in the frog, are less so in the _Hylidae_ and
_Bufonidae_, almost indistinguishable in the _Pelobatidae_ and
_Discoglossidae_, whilst in the Aglossa they do not exist any more
than in the other orders of batrachians.
No batrachian is known to possess an ossified azygous supra-occipital.
[Illustration: FIG. 9.--Lateral, dorsal and ventral views of the
cranium of _Necturus maculosus_. In the dorsal view, the bones are
removed from the left half of the skull, in the ventral view, the
parasphenoid, palato-pterygoid, and vomers are given in outline. The
letters have, for the most part, the same signification as before.
VII.p, Posterior division of the seventh nerve.
VII. Chorda tympani
V^1, V^2, V^3, First, second and third divisions of the trigeminal.
s.s.l, Stapedio-suspensorial ligament.
h.s.l, Hyo-suspensorial ligament.
m.h.l, Mandibulo-hyoid ligament.
a, Ascending process of the suspensorium.
p, Pterygo-palatine process.
q, Quadrate process.
o, Otic process.
Na, Posterior nares.
Mck, Meckel's cartilage.
Gl (fig. 10), The position of the glottis.
Bb^1, Bb^2, Basilbranchials.]
Although there are four branchial arches in all the larval forms of
the three orders, and throughout life in the _Sirenidae_, the
perennibranchiate _Proteidae_ have only three (see fig. 11). In the
adult Apoda these arches and the hyoid fuse into three transverse,
curved or angular bones (see fig. 13), the two posterior disconnected
from the hyoid. In the Ecaudata, as shown by F. Gaupp (29) and by W.G.
Ridewood (30), the whole hyobranchial apparatus forms a cartilaginous
continuum, and during metamorphosis the branchialia disappear without
a trace. The hyoid of the adult frog (fig. 12) consists of a plate of
cartilage with two slender cornua, three processes on each side, and
two long bony rods behind, termed the thyro-hyals, which embrace the
larynx. In the Aglossa, which are remarkable for the large size and
complexity of the larynx, the thyro-hyal bones are incorporated into
the laryngeal apparatus, whilst the recently discovered _Hymenochirus_
is further remarkable for the large size and ossification of the
hyoidean cornua (ceratohyals), a feature which, though not uncommon
among the salamanders, is unique among the Ecaudata (31).
[Illustration: FIG. 10--Dorsal, ventral, lateral, and posterior views
of the skull of _Rana esculenta_. The letters have the same
signification throughout.
Pmx, Premaxilla.
Mx, Maxilla.
Vo, Vomer.
Na, Nasal.
S.e, Sphen-ethmoid.
Fr, Frontal.
Pa, Parietal.
E.O, Exoccipital.
Ep, Epiotic process.
Pr.O, Pro-otic.
t.t, Tegmentympani.
Sq, Squamosal.
Q.J, Quadrato-jugal.
Pt1, Pterygoid, anterior process.
Pt2, Internal process.
Pt3, Posterior or external process.
Ca, Columella auris.
St, Stapes.
Hy, Hyoidean cornu.
P.S, Parasphenoid.
An, Angulate.
D, Dentale.
V, Foramen of exit of the trigeminal.
H, Of the optic.
X, Of the pneumogastric and glosso-pharyngeal nerves.
V1. Foramen by which the orbito-nasal or first division of the fifth
passes to the nasal cavity.]
The pectoral girdle of the Stegocephalia is, of course, only known
from the ossified elements, the identification of which has given rise
to some diversity of opinion. But C. Gegenbaur's (32) interpretation
may be regarded as final. He has shown that, as in the Crossopterygian
and Chondrostean ganoid fishes, there are two clavicular elements on
each side; the lower corresponds to the clavicle of reptiles and
higher vertebrates, whilst the upper corresponds to the clavicle of
teleostean fishes, and has been named by him "cleithrum." As stated
above, there is strong evidence in favour of the view that some forms
at least possessed in addition a "supracleithrum," corresponding to
the supra-clavicle of bony fishes. The element often termed "coracoid"
in these fossils would be the scapula. The clavicles rest on a large
discoidal, rhomboidal, or T-shaped median bone, which clearly
corresponds to the interclavicle of reptiles.
The pectoral girdle of the living types of batrachians is
distinguishable into a scapular, a coracoidal, and a praecoracoidal
region. In most of the Caudata the scapular region alone ossifies, but
in the Ecaudata the coracoid is bony and a clavicle is frequently
developed over the praecoracoid cartilage. In these batrachians the
pectoral arch falls into two distinct types--the _arciferous_, in
which the precoracoid (+clavicle) and coracoid are widely separated
from each other distally and connected by an arched cartilage (the
epicoracoid), the right usually overlapping the left; and the
_firmisternal_, in which both precoracoid and coracoid nearly abut on
the median line, and are only narrowly separated by the more or less
fused epicoracoids. The former type is exemplified by the toads and
the lower Ecaudata, whilst the latter is characteristic of the true
frogs (_Ranidae_), although when quite young these batrachians present
a condition similar to that which persists throughout life in their
lower relatives. A cartilage in the median line in front of the
precoracoids, sometimes supported by a bony style, is the so-called
Omosternum; a large one behind the cora-coids, also sometimes provided
with a bony style, has been called the sternum. But these names will
probably have to be changed when the homologies of these parts are
better understood.
[Illustration: FIG. 11.--Hyoid and branchial apparatus of _Necturus
maculosus_.
Hh, Hypo-hyal.
Ch, Cerato-hyal.
Bb^1, First basibranchial.
Bb^2, Ossified second basibranchial.
Ep.b^1, Ep.b^2, Ep.b^3, First, second and third epibranchials.
Gl, Glottis.]
The pelvic arch of some of the Stegocephalia contained a well ossified
pubic element, whilst in all other batrachians only the ilium, or the
ilium and the ischium are ossified. In the Ecaudata the ilium is
greatly elongated and the pubis and ischium are flattened, discoidal,
and closely applied to their fellows by their inner surfaces; the
pelvic girdle looks like a pair of tongs.
The long bones of the limbs consist of an axis of cartilage; the
extremities of the cartilages frequently undergo calcification and are
thus converted into epiphyses. In the Ecaudata the radius and ulna
coalesce into one bone. The carpus, which remains cartilaginous in
many of the Stegocephalia and Caudata, contains six to eight elements
when the manus is fully developed, whilst the number is reduced in
those forms which have only two or three digits. Except in some of the
Stegocephalia, there are only four functional digits in the manus, but
the Ecaudata have a more or less distinct rudiment of pollex; in the
Caudata it seems to be the outer digit which has been suppressed, as
atavistic reappearance of a fifth digit takes place on the outer side
of the manus, as it does on the pes in those forms in which the toes
are reduced to four. The usual number of phalanges is 2, 2, 3, 2 in
the Stegocephalia and Caudata, 2, 2, 3, 3 in the Ecaudata. In the foot
the digits usually number five, and the phalanges 2, 2, 3, 3, 2 in the
Caudata, 2, 2, 3, 4, 3 in the Stegocephalia and Ecaudata. There are
occasionally intercalary ossifications between the two distal
phalanges (33). There are usually nine tarsal elements in the Caudata;
this number is reduced in the Ecaudata, in which the two bones of the
proximal row (sometimes coalesced) are much elongated and form an
additional segment to the greatly lengthened hind-limb, a sort of
_crus secundarium_. In the Ecaudata also, the tibia and fibula
coalesce into one bone, and two or three small bones on the inner side
of the tarsus form what has been regarded as a rudimentary digit or
"prehallux."
[Illustration: FIG. 12.--Ventral view of the hyoid of _Rana
esculenta_. a, Anterior; b, lateral; c, posterior processes; d,
thyro-hyals.]
_Integument._--In all recent batrachians, the skin is naked, or if
small scales are present, as in many of the Apoda, they are concealed
in the skin. The extinct Stegocephalia, on the other hand, were mostly
protected, on the ventral surface at least, by an armour of
overlapping round, oval, or rhomboidal scales, often very similar to
those of Crossopterygian or ganoid fishes, and likewise disposed in
transverse oblique lines converging forwards on the middle line of the
belly. Sometimes these scales assumed the importance of scutes and
formed a carapace, as in the "batrachian armadillo" discovered by E.D.
Cope. A few frogs have the skin of the back studded with stellate bony
deposits (_Phyllomedusa, Nototrema_), whilst two genera are remarkable
for possessing a bony dorsal shield, free from the vertebrae
(_Ceratorphrys_) or ankylosed to them (_Brachycephalus_). None of the
Stegocephalia appears to have been provided with claws, but some
living batrachians (_Onychodactylus, Xenopus, Hymenochirus_) have the
tips of some or all of the digits protected by a claw-like horny
sheath.
The integument of tailed and tailless batrachians is remarkable for
the great abundance of follicular glands, of which there may be two
kinds, each having a special secretion, which is always more or less
acrid and irritating, and affords a means of defence against the
attacks of many carnivorous animals. A great deal has been published
on the poisonous secretion of batrachians (34), which is utilized by
the Indians of South America for poisoning their arrows. Some of the
poison-secreting glands attain a greater complication of structure and
are remarkable for their large size, such as the so-called "parotoid"
glands on the back of the head in toads and salamanders.
[Illustration: FIG. 13.--Ventral view of the head and trunk of
_Ichthyophis glutinosus_.
Mn, Mandible.
Hy, Hyoid.
Br^1 Br^2, Br^3, Branchial arches.
Gl, Glottis.
Tr, Trachea.
Ivc, Inferior vena cava.
V, Ventricle.
Au, Auricles.
Rsvc, Lsvc, right and left superior cavae.
Ta, Truncus arteriosus.
Ao, Left aortic arch.
P.A. Right pulmonary artery. The pericardium (lightly shaded)
extends as far as the bifurcation of the synangium.]
In all larval forms, in the Caudata, and in a few of the Ecaudata
(_Xenopus_, for instance), the epidermis becomes modified in relation
with the termination of sensory nerves, and gives rise to organs of
the same nature as those of the lateral line of fishes. In addition to
diffuse pigment (mostly in the epidermis), the skin contains granular
pigment stored up in cells, the chromatophores, restricted to the
cutis, which are highly mobile and send out branches which, by
contraction and expansion, may rapidly alter the coloration, most
batrachians being in this respect quite comparable to the famous
chameleons. Besides white (guanine) cells, the pigment includes black,
brown, yellow and red. The green and blue, so frequent in frogs and
newts, are merely subjective colours, due to interference. On the
mechanism of the change of colour, cf. W. Biedermann (35).
One of the interesting recent discoveries is that of the "hairy" frog
(_Trichobatrachus_), in which the sides of the body and limbs are
covered with long villosities, the function of which is still unknown
(36).
The nuptial horny asperities with which the males of many batrachians
are provided, for the purpose of clinging to the females, will be
noticed below, under the heading _Pairing and Oviposition_.
_Dentition._--In the Microsauria and Branchiosauria among the
Stegocephalia, as in the other orders, the hollow, conical or slightly
curved teeth exhibit simple or only slightly folded walls. But in the
Labyrinthodonta, grooves are more or less marked along the teeth and
give rise to folds of the wall which, extending inwards and ramifying,
produce the complicated structure, exhibited by transverse sections,
whence these batrachians derive their name; a somewhat similar
complexity of structure is known in some holoptychian (dendrodont)
Crossopterygian fishes. In the remarkable salamander _Autodax_, the
teeth in the jaws are compressed, sharp-edged, lancet shaped. The
teeth are not implanted in sockets, but become ankylosed with the
bones that bear them, and are replaced by others developed at their
bases. Teeth are present in the jaws of all known Stegocephalia and
Apoda and of nearly all Caudata, _Siren_ alone presenting plates of
horn upon the gingival surfaces of the premaxillae and of the dentary
elements of the mandible. But they are nearly always absent in the
lower jaw of the Ecaudata (exceptions in _Hemiphractus,
Amphignathodon, Amphodus, Ceratobatrachus_, the male of
_Dimorphognathus_), many of which (toads, for instance) are entirely
edentulous.
There is great variety in the distribution of the teeth on the palate.
They may occur simultaneously on the vomers, the palatines, the
pterygoids and the parasphenoid in some of the Stegocephalia
(_Dawsonia, Seeleya, Acanthostoma_), on the vomers, palatines and
parasphenoid in many salamandrids (_Plethodontinae_ and
_Desmognathinae_), on the vomers, pterygoids and parasphenoid (some
_Pelobates_), on the vomers and parasphenoid (_Triprion, Amphodus_),
whilst in the majority or other batrachians they are confined to the
vomers and palatines or to the vomers alone (37).
As regards the alimentary organs, it will suffice to state, in this
very brief sketch, that all batrachians being carnivorous in their
perfect condition, the intestine is never very long and its
convolutions are few and simple. But the larvae of the Ecaudata are
mainly herbivorous and the digestive tract is accordingly extremely
elongate and coiled up like the spring of a watch. The gullet is
short, except in the Apoda. The tongue is rudimentary in the
perennibranchiatea Caudata, well developed, and often protrusile, in
the _Salamandridae_ and most of the Ecaudata, totally absent in the
Aglossa.
The organs of circulation cannot be dealt with here; the most
important addition made to our knowledge in recent years being found
in the contributions of F. Hochstetter (38) and of G.B. Howes (39),
dealing with the azygous (posterior) cardinal veins in salamanders and
some of the Ecaudata. The heart is situated quite forward, in the
gular or pectoral region, even in those tailed batrachians which have
a serpentiform body, whilst in the Apoda (fig. 13) it is moved back to
a distance which is comparable to that it occupies in most of the
snakes.
_The Respiratory Organs._--The larynx, which is rudimentary in most of
the Caudata and in the Apoda, is highly developed in the Ecaudata, and
becomes the instrument of the powerful voice with which many of the
frogs and toads are provided. The lungs are long simple tubes in some
of the perennibranchiate Caudata; they generally shorten or become
cellular in the salamandrids, and attain their highest development in
the Ecaudata, especially in such forms as the burrowing _Pelobates_.
Although the lungs are present in such forms as preserve the gills
throughout life, it is highly remarkable that quite a number of
abranchiate salamanders, belonging mostly to the subfamilies
_Desmognathinae_ and _Plethodontinae_, are devoid of lungs and breathe
entirely by the skin and by the bucco-pharyngeal mucose membrane (20).
Some of the _Salamandrinae_ show the intermediate conditions which
have led to the suppression of the trachea and lungs. In the Apoda, as
in many serpentiform reptiles, one of the lungs, either the right or
the left, is much less developed than the other, often very short.
_Urino-genital Organs._--The genital glands, ovaries and testes, are
attached to the dorsal wall of the body-cavity, in the immediate
vicinity of the kidneys, with which the male glands are intimately
connected. The oviducts are long, usually more or less convoluted
tubes which open posteriorly into the cloaca, while their anterior
aperture is situated far forward, sometimes close to the root of the
lung; their walls secrete a gelatinous substance which invests the ova
as they descend. In most male batrachians the testes are drained by
transverse canals which open into a longitudinal duct, which also
receives the canals of the kidneys, so that this common duct conveys
both sperma and urine. In some of the discogloesid frogs, however, the
seminal duct is quite independent of the kidney, which has its own
canal, or true ureter. Many of the Ecaudata have remnants of oviducts,
or Mullerian ducts, most developed in _Bufo_, which genus is also
remarkable as possessing a problematic organ, Bidder's organ, situated
between the testis and the adipose or fat-bodies that surmount it.
This has been regarded by some anatomists as a rudimentary ovary.
Female salamandrids are provided with a _receptaculum seminis_.
Copulatory organs are absent, except in the Apoda, in which a portion
of the cloaca can be everted and acts as a penis. The urinary bladder
is always large.
The spermatozoa have received a great share of attention, on the part
not only of anatomists and physiologists, but even of systematic
workers (40). This is due to the great amount of difference in
structure and size between these elements in the various genera, and
also to the fact that otherwise closely allied species may differ very
considerably in this respect. The failure to obtain hybrids between
certain species of _Rana_ has been attributed principally to these
differences. The spermatozoa of _Discoglossus_ are remarkable for
their great size, measuring three millimetres in length.
_Pairing and Oviposition_--Batrachians may be divided into four
categories under this head:--(1) no amplexation; (2) amplexation
without internal fecundation; (3) amplexation with internal
fecundation; (4) copulation proper. The first category embraces many
aquatic newts, the second nearly all the Ecaudata, the third the rest
of the Caudata, and the fourth the Apoda.
In the typical newts (_Molge_) of Europe, the males are adorned during
the breeding season with bright colours and crests or other ornamental
dermal appendages, and, resorting to the water, they engage in a
lengthy courtship accompanied by lively evolutions around the females,
near which they deposit their spermatozoa in bundles on a gelatinous
mass, the spermatophore, probably secreted by the cloacal gland. This
arrangement facilitates the internal fecundation of the female without
copulation, the female absorbs the spermatozoa by squeezing them out
of the spermatophore between the cloacal lips. Other newts, and many
salamanders, whether terrestrial or aquatic, pair, the male embracing
the female about the fore limbs or in the pelvic region, and the males
of such forms are invariably devoid of ornamental secondary sexual
characters; but in spite of this amplexation the same mode of
fecundation by means of a spermatophore is resorted to, although it
may happen that the contents of the spermatophore are absorbed direct
from the cloaca of the male. The spermatozoa thus reach the eggs in
the oviducts, where they may develop entirely, some of the salamanders
being viviparous.
In all the tailless batrachians (with the exception of a single known
viviparous toad), the male clings to the female round the breast, at
the arm-pits, or round the waist, and awaits, often for hours or days,
the deposition of the ova, which are immediately fecundated by several
seminal emissions.
The fourth category is represented by the Apoda or Caecilians in
which, as we have stated above, the male is provided with an
intromittent organ. Some of these batrachians are viviparous.
In those species in which the embrace is of long duration the limbs
of the male, usually the fore limbs (pleurodele newt, Ecaudata),
rarely the hind limbs (a few American and European newts), according
to the mode of amplexation, acquire a greater development, and are
often armed with temporary horny excrescences which drop off after the
pairing season. These asperities usually form brush-like patches on
the inner side of one or more of the digits, but may extend over the
inner surface of the limbs and on the breast and chin; the use of them
on these parts is sufficiently obvious, but they are sometimes also
present, without apparent function, on various parts of the foot, as
in _Discoglossus, Bombinator_, and _Pelodytes_. In some species of the
South American frogs of the genus _Leptodactylus_ the breast and hands
are armed with very large spines, which inflict deep wounds on the
female held in embrace.
In most of the Caudata, the eggs are deposited singly in the axils of
water plants or on leaves which the female folds over the egg with her
hind limbs. The eggs are also deposited singly in some of the lower
Ecaudata. In many of the Ecaudata, and in a few of the Caudata and
Apoda, the eggs are laid in strings or bands which are twined round
aquatic plants or carried by the parent; whilst in other Ecaudata they
form large masses which either float on the surface of the water or
sink to the bottom.
A few batrachians retain the ova within the oviducts until the young
have undergone part or the whole of the metamorphosis. Viviparous
parturition is known among the Caudata (_Salamandra, Spelerpes
fuscus_), and the Apoda (_Dermophis thomensis, Typhlonectes
compressicauda_); also in a little toad (_Pseudophryne vivipara_)
recently discovered in German East Africa (41).
_Development and Metamorphosis._--In a great number of batrachians,
including most of the European species, the egg is small and the
food-yolk is in insufficient quantity to form an external appendage of
the embryo. But in a few European and North American species, and in a
great many inhabitants of the tropics, the egg is large and a
considerable portion of it persists for a long time as a yolk-sac.
Although the segmentation is always complete, it is very irregular in
these types, some of which make a distinct approach to the meroblastic
egg.
With the exception of a number of forms in which the whole development
takes place within the egg or in the body of the mother, batrachians
undergo metamorphoses, the young passing through a free-swimming,
gill-breathing period of considerable duration, during which their
appearance, structure, and often their _regime_, are essentially
different from those of the mature form. Even the fossil Stegocephalia
underwent metamorphosis, as we know from various larval remains first
described as _Branchiosaurus_. They are less marked or more gradual in
the Apoda and Caudata than in Ecaudata, in which the stage known as
tadpole is very unlike the frog or toad into which it rather suddenly
passes (see TADPOLE). In the Caudata, external gills (three on each
side) persist until the close of the metamorphosis, whilst in the
Apoda and Ecaudata they exist only during the earlier periods, being
afterwards replaced by internal gills.
Many cases are known in which the young batrachian enters the world in
the perfect condition, as in the black salamander of the Alps
(_Salamandra atra_), the cave salamander (_Spelerpes fuscus_), the
caecinan _Typhlonectes_, and a number of frogs, such as _Pipa,
Rhinoderma, Hylodes_, some _Nototrema, Rana opisthodon_, &c. A fairly
complete bibliographical index to these cases and the most remarkable
instances of parental care in tailless batrachians will be found in
the interesting articles by Lilian V. Sampson (42), and by G. Brandes
and W. Schoenichen (43). It will suffice to indicate here in a
synoptic form, as was done by the present writer many years ago, when
our knowledge of these wonders of batrachian life was far less
advanced than it is now, the principal modes of protection which are
resorted to:--