Latterly these creatures have frequently been brought over to England. They stand confinement very well, even in a little aquarium with sufficient water-weeds to keep the water fresh; and they do not require special heat. They greedily snap up worms, strips of liver, or meat, and poke the food in with their hands. A few kept by Boulenger in a glass jar have lived for the last eleven years in the ordinary temperature of a room in London. Curiously enough they are often in amorous embrace, regardless of the season, but they have never shown any signs of spawning.

Some of those in the Zoological Gardens in London laid eggs on Saturday the 27th of May, and on the morning of the following Monday the larvae were already hatched. They have been described by Beddard.^[74] The larvae are provided with an unpaired circular, ventral sucker. The tentacles begin to sprout out on the sixth day after hatching, at first not in connexion with the cranial cartilage, but soon a cartilaginous rod runs into the tentacle from the ethmoid "just above the joint with the under jaw.". Boulenger has most reasonably compared these organs with the "balancers" of Triton and Amitystoma (cf. p. 46 for the possible homologies of the balancers). The tentacles soon reach a great length and give the tadpole a curious appearance. In tadpoles of X. calcaratus, 65 mm. long, the tentacles are 30 mm. long, and are inserted just at the angle of the mouth. By the time that these tadpoles show their fore-limbs, the feelers are reduced to 4 mm. in length, and their relative position has been shifted to a little above the angle of the gape, and whilst the latter gradually extends further and further back, the feelers come to lie, or rather remain, below and a little in front of the eyes.

The tadpoles have no traces of horny teeth. External gills project as low conical or lamellar processes from the first three branchial arches, but so-called internal gills are not developed.

Amongst a number of Clawed Toads imported in the spring one female became swollen with eggs, but as they did not show signs of wanting to breed, a pair was put into the tropical tank in the Cambridge Botanic Gardens, a transfer which had the desired effect. Eggs were laid, and more during the following nights; they hatched out within thirty hours. The whole brood was lost, before any of them were older than a few days, since they were attacked, beyond the possibility of a cure, by a Saprolegnia or some similar pest.

Hymenochirus, represented by one species, H. boettgeri, has been discovered in the Ituri, German East Africa, and in the French Congo, and has no doubt a much wider distribution. It is scarcely 1½ inch long, and is easily recognised by the toothless mouth, the half-webbed fingers (hence the generic name), the incompletely webbed toes, the third of which is longer than the fourth, and the absence of sensory muciferous canals in the skin. The three inner toes are, as in Xenopus, furnished with small black claws. The skin is rough, beset with small granular tubercles. The general colour above and below is olive-brown. The vent is, as in Xenopus, produced into a spout or semi-canal, but is devoid of dorsal flaps of skin.

Pipa.–This Neotropical member of the Aglossa is quite toothless, but the jaws of the adult have horny substitutes. The only species is P. americana, the famous Surinam Toad, chiefly known from the Guianas, but undoubtedly extending much further, having recently been reported from the neighbourhood of Pará.

The general shape of this creature is very peculiar. The head is much depressed and triangular; the eyes are very small; the skin forms several short, irregularly-shaped flaps and tentacles on the upper lips and in front of the eye, and at the angle of the mouth. The tympanum is invisible. The pupil is round. The fingers are very slender and free, ending in star-shaped tips; the toes are broadly webbed. The whole skin is covered with small tubercles and is dark brown above, while the under parts of the very flat and depressed body are whitish, sometimes with a dark brown stripe along the middle line. In the female the skin of the back forms growths for the reception of the eggs, and in these the young undergo their whole metamorphosis.

The most characteristic feature of the skin,^[75] which has exactly the same structure in both sexes, is the papillae, which are spread over the whole surface, except on the webs of the toes, on the cornea and on the star-shaped points of the fingers. Each papilla carries a little horny spike, and a poison-gland frequently opens near its base. Larger poison-glands exist on the dorsal and ventral side in four rows, and smaller glands open upon the sides of the body, but there are no parotoid complexes. Slime-glands occur all over the surface. The epidermis consists of the usual layers, namely the Malpighian, the stratum corneum, and the part which is shed periodically. The latter is completely horny, appearing to be structureless like a cuticle, but it is in reality composed of polygonal cells with flattened nuclei; each little spike is one modified horny cell. The whole outermost layer contains black-brown pigment. The upper portion of the cutis is devoid of pigment, then follows a layer of clusters of ramified dark pigment-cells, and lastly the rest of the cutis.

Each of the four fingers ends in a four-armed star, the tips of which again carry four or five sensory papillae. The cartilage of the terminal phalanges is correspondingly star-shaped.

According to Klinckowstroem these toads, which are entirely aquatic, are easily collected at the end of the long dry period, when they are all confined to the half-dried-up pools. But they do not spawn there. This happens after the rains have inundated the forest, and then it is very difficult to get the females with eggs on their backs. Each of the eggs, when once they have been glued on to the back, sinks into an invagination of the skin. The initial stages are probably the same as those caused by the eggs on the belly of Rhacophorus reticulatus (see p. 248). Later, each egg is quite concealed in a cavity with a lid. These cavities are simply pouches of the skin, and are not formed by enlarged glands as has been suggested by some anatomists. Each cavity consists of the epidermal pouch and the lid. How the latter is produced is not known. According to the authors quoted above, the lid looks like a shiny or sticky layer which has hardened into horn-like consistency. It lies exactly like a lid upon the rim of the pouch itself, and is certainly not in structural or organic continuity with the epidermis. Most probably it is produced by the remnant of the egg-shell itself, which, after the larva is hatched, is cast up to and remains on the top of the cup.

Bartlett^[76] has described the spawning of specimens in the Zoological Gardens in London.

"About the 28th of April 1896 the males became very lively, and were constantly heard uttering their most remarkable metallic, ticking call-notes. On examination we then observed two of the males clasping tightly round the lower part of the bodies of the females, the hind parts of the males extending beyond those of the females. On the following morning the keeper arrived in time to witness the mode in which the eggs were deposited. The oviduct of the female protruded from her body more than an inch in length, and the bladder-like protrusion being retroverted, passed under the belly of the male on to her own back. The male appeared to press tightly upon this protruded bag and to squeeze it from side to side, apparently pressing the eggs forward one by one on to the back of the female. By this movement the eggs were spread with nearly uniform smoothness over the whole surface of the back of the female to which they became firmly adherent. On the operation being completed, the males left their places on the females, and the enlarged and projected oviduct gradually disappeared from one of the females. In the other specimen, the oviduct appears not to have discharged the whole of the eggs."

Boulenger, who examined this second specimen, which died, confirmed this egg-bound condition. He remarks further: "The ovipositor formed by the cloaca (not by the prolapsed uterus), was still protruding and much inflamed. It may be deduced from the observation made by the keeper, that fecundation must take place before the extrusion of the eggs, and it is probable that the ovipositor serves in the first instance to collect the spermatozoa which would penetrate into the oviducts, the eggs being laid in the impregnated condition, as in tailed Batrachians."

Sub-Order 2. Phaneroglossa–Fam. 1. Discoglossidae.–The tongue has the shape of a round disc, adherent by nearly the whole of its base, and it cannot be protruded. The vertebrae are opisthocoelous, and in the aquatic genera are of the most exaggerated epichordal type; the diapophyses of the second to the fourth vertebrae carry short, free ribs, and those of the sacral vertebra are dilated. The metasternum behind is forked. The upper jaw and the vomers are provided with teeth. The males have no vocal sac. The tadpoles are distinguished by having the opercular spiracle placed in the middle of the thoracic region (see general anatomical part, p. 44).

The few members of this family have a peculiar distribution. Liopelma is confined to New Zealand, where it is the solitary representative of the Amphibia. Ascaphus is found in North America. The other genera, Discoglossus, Bombinator, and Alytes, are typical of the Palaearctic sub-region, and are, with the exception of Bombinator, confined to the Western Provinces (cf. Map, Fig. 32, on p. 161).

Discoglossus.–The tympanum is frequently more or less concealed by the skin. The pupil is round or triangular. The omosternum is small. The vertebrae are of the epichordal type.

D. pictus, the only species, has a smooth and shiny skin, provided with numerous small mucous glands. The palms of the hands are provided with three tubercles, of which the innermost is the largest, and is carried by the vestige of the thumb. The coloration of this species is very variable. The ground-colour of the upper parts is a rich olive brown with darker, light-edged patches, which are either separate or confluent in various ways, forming broad, longitudinal bands, or a few larger asymmetrical patches, separated in some individuals by a broad and conspicuous light brown or yellowish vertebral stripe. An irregular reddish band frequently extends from the eyes backwards along the sides. The under parts are mostly yellowish white. This variability is purely individual, the most differently marked and variously coloured specimens being found in the same locality and even amongst the members of one and the same brood. The male develops various nuptial excrescences, consisting of minute, dark, horny spines, notably on the inner palmar pad, on the inner side of the first and second finger, on the chin and throat, and smaller and more scattered spicules on the belly and legs.

This pretty and extremely active little creature, which measures between 2 and 3 inches in length, is confined to the south-western corner of the Palaearctic sub-region, being found in Algiers and Morocco, Sicily, Sardinia, Corsica, and the southern and western parts of the Iberian Peninsula. Curiously enough it is absent in the Balearic Isles. Rather aquatic in its habits, frequenting pools and streams, it is also often found on land.

The male has a feeble voice, which sounds like "ha-a, ha-a-a," or "wa-wa-wa," uttered in rapid succession. The pairing season lasts a long time, in Algeria from January to October, but a much shorter time in the north of Portugal, where it extends over the spring and summer months. Boulenger has made extensive observations on many specimens kept in captivity. The embrace, which never lasts long, is lumbar. The eggs are small, 1 to 1.5 mm. in diameter, dark brown above and greyish below, each surrounded by a gelatinous capsule of 3-7 mm. in diameter. The eggs are laid singly, and a set amounts to from 300 to 1000, the whole mass sinking to the bottom of the pool. Each female lays several times during the season. The eggs are developed very rapidly, the larvae escaping sometimes after thirty-six hours, but usually from the second to the fourth day. The external gills are lost on the seventh day, when the tadpoles are 11 mm. long; the hind-limbs appear on the tenth, and after four weeks the tadpoles reach their greatest length, namely from 25-30 mm. The fore-limbs appear on the thirtieth day, and a few days later the most precocious specimens leave the water and hop about. Others, however, of the same brood took from two to three months in metamorphosing.

This species lives on insects and worms, and can swallow its prey under water.

Bombinator.–The tympanum is absent and the Eustachian tubes are very minute. The pupil is triangular. The omosternum is absent. The vertebrae are absolutely epichordal. The fingers are free, the toes are webbed. The upper parts are uniformly dark, and are covered with small porous warts. The general shape of the head and body is depressed or flattened downwards. The habits are eminently aquatic. This genus consists of three species, two of which are European, the third Chinese.

B. igneus.–The under parts are conspicuously coloured bluish black with large irregular red or orange-red patches; the upper parts are more or less dark grey or olive black. The iris is golden, speckled with brown. The male has a pair of internal vocal sacs by which the throat can be inflated; nuptial excrescences are developed on the inner side of the fore-arm and the first two fingers. Total length from 1½ to 2 inches, the males being generally smaller than the females. This "Fire-bellied toad," the "Unke" of the Germans, is essentially a native of lakes, ponds, and other standing waters of the plains.

It ranges through the whole of North Germany, Bohemia, and Hungary into Russia, eastwards as far as the Volga. The latter river, the Danube, and the Weser form, roughly speaking, its boundaries; northwards it extends into Denmark and the southern extremity of Sweden.

B. pachypus.–The under parts are yellow instead of red. The male is devoid of vocal sacs, but has nuptial excrescences on the under surface of most of the toes, in addition to those on the fore-arm and fingers. The "Yellow-bellied Toad" is the representative of the red-bellied species in Southern and Western Europe, preferring, although not exclusively, the hilly and mountainous districts. It ranges from France and Belgium through South-Western Germany, continental Italy, and the whole of Austria and Turkey in Europe. Where both species meet, for instance in the hilly districts between the Weser and the Rhine, in Thuringia and in Austria, the predilection of the yellow-bellied species for the hills, and that of the other for the plains, is well marked.

While B. igneus prefers standing waters with plenty of vegetation, B. pachypus is often found in the smallest occasional puddles produced by recent rain, for instance in the ruts of roads. Both species have otherwise much in common. They are essentially aquatic. They hang in the water, with their legs extended, nose and eyes just above the surface, and bask or lie in wait for passing insects, the fire-bellied kind preferring to conceal itself in the vegetation of the margins of ponds. During the pairing season, in Germany in the month of May, they are very lively and perform peculiar concerts, one male beginning with a slowly repeated note like "hoonk, hoonk," or "ooh, ooh," in which all the other males soon join, so that, when there are many, an almost continuous music is produced. This sound is not at all loud, a little mournful and very deceptive. It appears to be a long way off, certainly at the other end of the pond, until by careful watching you see the little creature almost at your very feet. But on the slightest disturbance the performance ceases, they dive below and hide at the bottom. The yellow-bellied kind, when surprised in a shallow puddle, skims over the mud, disturbs it, and allows it to settle upon its flat body, so that nothing but the little glittering eyes will betray its concealment. When these toads are surprised on land, or roughly touched, they assume a most peculiar attitude, as shown in Fig. 31. The head is partly thrown back, the limbs are turned upwards with their under surfaces outwards, and the whole body is curved up so that as much as possible of the bright yellow or red markings of the under parts is exposed to view. The creature remains in this strained position until all danger seems passed. In reality this is an exhibition of warning colours, to show the enemy what a dangerous animal he would have to deal with. The secretion of the skin is very poisonous, and the fire-toads are thereby well protected. I know of no creature which will eat or even harm them. I have kept numbers in a large vivarium, together with various snakes, water-tortoises, and crocodiles, but for years the little fire-bellies remained unmolested, although they shared a pond in which no other frog or newt could live without being eaten. Hungry water-tortoises stalk them under water, touch the intended prey with the nose in order to get the right scent, and then they withdraw from the Bombinator, which has remained motionless, well knowing that quick movements, or a show of escape, would most likely induce the tortoise to a hasty snap, with consequences to be regretted by both.

After they have been handled frequently, they do not readily perform, but simply lie still, or hop away. Miss Durham experienced considerable difficulty in inducing her tame specimens to assume and to keep up the correct warning attitude. The statement that they "turn over on the back" is a fable, graphically fixed in various illustrated works.

It has been said that these two species are diurnal and thoroughly aquatic. They are certainly active in the daytime, sing in full sunshine, and spend most of their time in the water, but they display much more liveliness towards the evening and during the night, especially when there is a moon. My fire-toads live by no means always in the water, but conceal themselves in the daytime under stones, while they are regularly all astir at night in search of worms and all kinds of small insects.

The spawning takes place several times during the spring and summer. The amplexus is lumbar, and the eggs are extruded singly. They sink to the bottom, or are attached to water-plants. The oviposition takes a long time, perhaps the whole night, and several dozen eggs, not hundreds as in the allied genera, make a set. The egg, with its swollen gelatinous capsule, is large for so small a creature, namely 7-8 mm. in diameter. The embryos escape after a week, and the tadpoles reach two inches in total length. Those of B. igneus have a triangular mouth, but in B. pachypus this is elliptical, as in Alytes and Discoglossus. Metamorphosis is completed in the same autumn; the little toad is then about 15 mm. long, and differs from the adult by the absence of the conspicuous coloration of the under parts. In reasonable conformity herewith it does not take up the warning attitude. The colour appears gradually during the second year, but full growth is generally not reached until the third year. They do not hibernate in the water, but hide on land out of the reach of frost.

Alytes.–The tympanum is distinct, the pupil vertical, the omosternum is absent. The only two species live in South-Western Europe. The male attaches the eggs to its hind limbs, and nurses them until they are hatched.

A. obstetricans, the "Midwife-toad," has the general appearance of a smooth toad. The upper parts are rather smooth, sometimes almost shiny, in spite of the numerous more or less prominent warts, of which those of the lateral lines, and those above the ear, are generally most marked. The colour of the upper parts varies a great deal according to the prevalence of greenish and reddish spots upon the grey or brown ground-colour. The red is sometimes, especially in the breeding males, rather conspicuous on the parotoid region and on the upper sides of the body. The under parts are whitish grey. The iris is pale golden, with black veins. The male has no vocal sac, and is as a rule smaller than the female, the latter reaching a length of two inches.

This species occurs in the whole of the Iberian Peninsula and in France, extending into Switzerland and beyond the Rhine valley into Thuringia. Altitude above the sea does not seem to have any influence upon its range, which reaches from sea-level to the tops of subalpine mountains. I have found great quantities of its tadpoles in Portugal on the Serra d'Estrella, nearly 6000 feet high, and they are recorded from 6500 feet in the Pyrenees. They seem to be ubiquitous in Spain and Portugal, not that they are often found or seen, but they are heard everywhere; besides, tadpoles are sure to be in the clear cold lakes on the tops of the mountain-ranges, in the dirty puddles caused by the village fountains, and in the sun-heated swampy ditches on the roadside with scarcely enough water to hold the wriggling mass. Wherever there is water within easy reach, on the lonely mountains, in fertile valleys, in the gardens of the busy towns, you hear during the whole night, from March to August, the double call-note of the male, sounding like a little bell; but to see the performer is quite a different matter. He sits in front of his hole, dug out by himself or appropriated from a mouse, in a crack of the bottom of a wall, under stones, or in a similar place into which he withdraws for the day.

The pairing and the peculiar mode of taking care of the eggs by the male, which habit has given it the specific name obstetricans, the midwife, have been most carefully observed by A. de l'Isle du Dréneuf, near Nantes. A condensed account has been given by Boulenger. Several males collect around a female on land, not in the water, and the successful one grasps her round the waist. For nearly half an hour the male lubricates the cloacal region of the female by more than one thousand strokes of his toes, whereupon the female extends the hind-limbs, forming with the bent hind-limbs of the male a receptacle for the eggs, which are then expelled with a sudden noise. The eggs are yellow and large, up to 5 mm. in diameter, and are fastened together in two rosary-like strings, several dozen making one set. During the expulsion of the eggs the male shifts its body forwards, clasps his fore-limbs round the female's head, and fecundates the eggs. After a rest he pushes first one hind-limb and then the other through the convoluted mass of eggs, which then have the appearance of being wound round the hind-limbs in a figure of 8. Then the sexes separate and the male withdraws with its precious load into its hole, which it, however, leaves during the following nights, in search of food, taking this opportunity to moisten the eggs in the dew, occasionally even immersing them in the water. After at least three weeks, when the larvae are nearly ready, he betakes himself to the nearest water, and the larvae burst the thereby softened gelatinous cover of the eggs. Not infrequently the same male ventures upon a second pairing, and adds another load to the one which already hampers its movements. The eggs being large, owing to the great amount of yellow food-yolk, the embryos are enabled to be hatched in a more advanced stage than in most other Anura. The larva develops only one pair of external gills within the egg. These appear first in the shape of oval bags upon the third branchial arch, which sprout out secondary branches, soon in their turn to be resorbed and replaced by the so-called internal gills before hatching.

Fischer-Sigwart^[77] gives the following account of the growth of this species. The male took to the water, with its load of twenty to thirty eggs, on the 6th of June. The larvae escaped out at once, 16-17 mm. long, the body measuring 5 mm. On the 14th they had reached 32 mm. in length, whereupon they grew very slowly, although they were well fed, in a temperature of about 50° F. This same brood did not metamorphose until May of the next year. The growth took place as follows:–The hind-limbs appeared on the 8th of September, when the tadpoles were 50 mm. long; by the middle of the next May they had reached their greatest length, 76 mm., the hind-limbs being 18 mm. long, whilst the fore-legs were just indicated. On the 21st of May the hind-limbs were 27 mm. long, and the whole creature was practically metamorphosed, except for the tail. The latter was resorbed on the 13th of July, and the little toads, 25 mm. in length, were actually smaller, certainly far less bulky and heavy, than the tadpoles, which had required one year and a quarter for their metamorphosis.

The early broods probably finish their development by the autumn of the same year, but those which are born later, in July and August, certainly hibernate in the water. I have found very small tadpoles, scarcely 15 mm. long, on the Cantabrian mountains as late as the end of September, and rather large ones in the spring at the time of first pairing; the fact that this takes place during the whole summer explains the occurrence of tadpoles in all stages of development almost the whole year round.

A. cisternasi has only two palmar tubercles, the middle or third one of A. obstetricans being absent; the outer finger is short and thick. Instead of a very long and wide fronto-parietal fontanelle, the fronto-parietal bones diverge only in front so that there are two fontanelles, a small one in the parietal and a large triangular one in the frontal region. The limbs are relatively shorter and stouter in conformity with the habits of this species, which prefers to burrow in sandy localities. Otherwise it leads the same kind of life as A. obstetricans, and the male carries the eggs. It has hitherto been found in Central Spain and in the middle provinces of Portugal.

Liopelma is intermediate between Alytes and Bombinator, agreeing with the latter, in conformity with its essentially aquatic life, in the absence of a tympanum, while the Eustachian tubes are entirely suppressed. The tongue is disc-shaped, but is slightly free behind. The pupil is triangular. The male is devoid of a vocal sac. L. hochstetteri is the sole representative of the Amphibia in New Zealand, where it is apparently rare. The upper parts are covered with smooth tubercles, and are dark brown with blackish spots; the under parts are whitish. Total length only 1½ inch.

Fam. 2. Pelobatidae.–The upper jaw and, as a rule, the vomers are provided with teeth. The tongue is oval, slightly nicked, and free behind, so that it can be thrown out, except in Asterophrys turpicola of New Guinea, which has a large but entirely adherent tongue. The vertebrae are procoelous, except in Asterophrys and the Malay genus Megalophrys, where they are opisthocoelous. The sacral diapophyses are strongly dilated. The omosternum is small and cartilaginous. The metasternum has a bony style, and ends in a cartilaginous, rounded or heart-shaped disc, but in Scaphiopus it forms an entirely cartilaginous plate. The tympanic disc is mostly hidden or indistinct, and is quite absent in Pelobates. The Eustachian tubes are very small in Pelobates, and exceedingly minute in Scaphiopus stagnalis of New Mexico. The pupil is vertical. This family contains seven genera with about twenty species, with a rather scattered distribution.

Pelobates ("Spade-foot").–The tympanum is absent; the toes are webbed. The inner tarsal tubercle is large, and is transformed into a shovel which is covered with a hard, sharp-edged, horny sheath. The skin of the upper surface of the head is partly co-ossified with the underlying cranial bones, giving them a pitted appearance. The general shape is toad-like.

P. fuscus.–The smooth skin is brown above, with darker marblings, while the under parts are whitish, but the coloration varies greatly, from pale to dark brown or olive-grey with more or less prominent irregular dark, sometimes confluent, patches. Some specimens are adorned with numerous red spots. The tarsal spur is yellow or light brown. The iris is metallic red or golden. The male has a long oval gland on the upper surface of the upper arm, and although possessed of a voice, has no vocal sacs. The total length of full-grown females is nearly 3 inches, that of males half an inch less.

The "Spade-footed Toad," which occurs throughout the whole of Central Europe, extends from Belgium and the middle of France to North-Western Persia, and from the southern end of Sweden to Northern Italy. It prefers sandy localities, in order to dig its deep hole, in which it sits concealed during the daytime. Owing to the looseness of the sand, the hole is filled up so that no trace of its inhabitant is left. The digging is done by means of the spades, and in suitable localities the animal soon vanishes, sinking backwards out of sight. Except in the breeding season, or at night, it is therefore found only accidentally. The sand-loving habits do not, however, prevent it from enjoying moist localities. Several which I have kept for years dig themselves into the wettest moss in preference to the drier parts of their habitation. Being thoroughly nocturnal, they hunt after nightfall, the food consisting of all sorts of insects and of worms. When captured they utter a startling shrill cry, and their skin becomes covered with a dermal secretion which smells like garlic, a peculiarity which has given them in Germany the name of "Knoblauchskröte," "garlic-toad." Although they become very tame, so that they no longer smell when handled, they can be made ill-tempered by being pinched or otherwise teased, whereupon they take up a defiant attitude, and with open mouth continue to cry for several minutes. Some such scenes occur now and then, without my interference, with the specimens which share their abode with several species of Amblystoma and Spelerpes; there are heard now and then sudden loud yells, like the squeak of a cat or the yapping of a little dog.

In the spring the Spade-footed Toads take to the water for about a week, and the male's call-note is an ever-repeated clucking sound, which can also be produced under water, with the mouth shut, the air being shifted backwards and forwards through the larynx. The male grasps his mate below the waist; the eggs are combined into one thick string, which is about 18 inches long, and is wound round and between the leaves and stalks of water-plants. The eggs measure 2-2.5 mm., and are very numerous, a large string containing several thousands. The larvae are hatched on the fifth or sixth day in a very unripe condition. They are only 4 mm. long, quite black, and still devoid of gills and tail. They attach themselves to the empty gelatinous egg-membranes, which they possibly live upon. On the following day the tail begins to grow; two days later fringed external gills sprout out and serve for about ten days, when they in turn give way to new, inner gills. The little tadpoles then leave their moorings and become independent. The hind-limbs appear in the ninth week, the fore-limbs in the twelfth. At the age of three months they begin to leave the water. The most remarkable feature is the enormous size of the full-grown tadpole, the body of which is as large as a pigeon's egg; the usual total length, including the tail, amounts to about 4 inches or 100 mm., but occasionally regular monsters are found. This was the case some thirty years ago, when the Berlin Museum received a number of tadpoles, the largest of which measured nearly 7 inches. They were found in the month of December near Berlin, in a deep clay-pit with high, steep walls, so that the tadpoles were prevented from leaving the water. Similarly hemmed-in broods probably hibernate in the water under the ice, and such instances have been recorded. Normally they metamorphose into the much smaller toad within the same year.

P. cultripes.–This is the Spade-foot of the whole of Spain and Portugal and of the southern and western parts of France. It is similar in habits to P. fuscus, from which it differs but slightly. The tarsal spur is black, and there is a parieto-squamosal bridge which completely roofs over the temporal fossa and closes the orbit behind.–Boulenger has discovered the rare, individual occurrence of minute teeth on the parasphenoid and on the pterygoids of this species. These teeth are unquestionably the last reminiscences of a condition almost entirely superseded in the recent Anura.

P. syriacus from Asia Minor and Syria agrees with P. cultripes in the cranial configuration, but has the yellow or brown spur of P. fuscus.

Scaphiopus.–The Spade-foot of North America and Mexico differs slightly from those of Europe, chiefly by the presence of a more or less hidden tympanum and of a subgular vocal sac, and by the sternum, which forms an entirely cartilaginous plate without a special style. The close relationship of these two genera is further indicated by the occurrence of peculiar large glandular complexes in some of the species, pectoral in S. solitarius, tibial in S. multiplicatus of Mexico. At the same time this genus approaches Pelodytes.–About eight species are known, two of which inhabit the United States, the others Mexico.

S. solitarius is the commonest species of the Southern States. It is brown above, with darker patches; its total length is about 2 inches. According to Holbrook it excavates small holes half a foot deep, in which it resides, seizing upon such unwary insects as may enter its dwelling. It never leaves the hole except in the evening or after long-continued rains. It appears early in March, and soon pairs; as an instance of hardiness Holbrook mentions that he has met it whilst there was still snow on the ground. When teased they assume a humble attitude, bending the head downwards with their eyes shut, as illustrated by Boulenger.^[78]

Pelodytes is, like the rest of the genera, devoid of the tarsal digging spur. The tympanic disc is rather indistinct; the male has a subgular sac. The general appearance of the slender body with long hind-limbs and toes is frog-like. Two species only are known, one in South-Western Europe, the other in the Caucasus.

P. punctatus.–The "Mud-diver" has the upper parts covered with small warts, and is about 1½ inch in length. Its coloration is variable, and changes much. One day it may appear greenish brown, the next day pale grey; in the daytime perhaps with many bright green spots, and in the evening spotless and unicoloured. The under parts are mostly white, sometimes with a fleshy tinge. The male has a voice like "kerr-kerr" or "creck-creck," uttered during the breeding season, which lasts from the end of February until May, according to the temperature and the more Southern or Northern locality. Occasionally they breed a second time in the summer or autumn. The male develops nuptial excrescences, chiefly three rough patches on the inner side of the fore-limbs or on the inner side of the first two fingers, while the belly and thighs are covered with small granules. In the mode of copulation, the laying of the small and numerous eggs, the hatching of the larvae in a tail- and gill-less condition, this genus closely resembles Pelobates; but the tadpoles never reach a colossal size, the usual length being 2 inches, and even this is comparatively large for so small a species. It inhabits the greater part of France, most of Portugal, and the southern half of Spain, avoiding, however, the central plateaux and the mountain-ranges. Its habits are essentially nocturnal, living in the immediate vicinity of the water, into which it hops with a long jump in order to hide in the mud. Easily kept, it breeds regularly in captivity, according to circumstances at almost any time of the year.

P. caucasicus has been discovered in the Caucasus at an altitude of 7000 feet. The remaining genera of this family contain only a few species each, and are restricted to South-Western Asia, the Malay and Papuan Islands. The commonest is Leptobrachium, which ranges from the Himalayas to Borneo and Java. Pupil vertical. Vomerine teeth sometimes absent. Tongue roundish, very slightly nicked behind. Tympanum indistinct. Omosternum small, cartilaginous. Male with internal vocal sacs. Tarsus with a roundish tubercle. Some of the species, e.g. L. carinense from the Karen Hills, attain to a large size, namely, 6 inches; they seem to live on rats and mice, and one specimen contained a young squirrel.

Fam. 3. Bufonidae (Toads).–The formula:–no teeth in the upper and lower jaws, vertebrae procoelous and without ribs, sacral diapophyses dilated,–is sufficiently diagnostic of this cosmopolitan family. The generally entertained notion that toads have a rather thick-set, short-limbed, warty appearance, does not apply to all the members of the family. The majority are quite terrestrial, many are burrowing, the Javanese Nectes is aquatic, the Afro-Indian Nectophryne is arboreal, while the Australian Myobatrachus and the Mexican Rhinophrynus eat termites and are correspondingly modified; lastly, Bufo jerboa is a slender, long-legged creature.

Teeth are almost entirely absent, except in Notaden, which has teeth on the vomers. The omosternum is mostly absent, except in Engystomops and in some species of Bufo, while in Notaden it is merely vestigial. The metasternum shows more variety. The tympanum is usually distinct, but varies even within the same genus, being hidden beneath the skin or being entirely absent. The terminal phalanges are modified according to the habits of the species, but they are never claw-shaped.

The Bufonidae are connected in various directions. The Neotropical Engystomops greatly resembles the likewise Neotropical Cystignathoid Paludicola, and the Australian Pseudophryne closely approaches the Australian Cystignathoid Crinia. It is therefore all the more remarkable that a similar approach, in another direction, namely, towards the Firmisternal family of the Engystomatidae, is indicated by the Mexican Rhinophrys and the Australian Myobatrachus. However, since there are no true Engystomatidae in Australia, although several genera occur in Papuasia, these cases may be instances of convergence without necessarily implying relationship. An unmistakable line of connexion leads, according to Boulenger, to the Pelobatidae, the link being the Himalayan Cophophryne, with very strongly dilated sacral diapophyses, with a single condylar articulation of the coccyx with the sacral vertebra (as in some Indo-Malayan Pelobatidae), while this articulation is bicondylar in all the other Bufonidae.

The whole family is divided into nine genera with more than a hundred species, of which only about fifteen do not belong to the genus Bufo. The distribution of the family is well-nigh cosmopolitan, with the remarkable exception of Madagascar, Papuasia, and the small islands of the Pacific; Bufo has been wrongly said to inhabit the Sandwich Islands. The greatest number of species, chiefly Bufo, occur in the Neotropical region, the greatest number of genera in Central America, where Bufo is rare, and in Australia, where it is absent.