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.