B. melanostictus is the common toad of the whole Indian region and of the Malay Archipelago. The epidermis of the fingers and toes is thicker and more cornified than usual, and is stained black brown, hence its specific name. The male has a subgular vocal sac. In other respects the Indian species much resembles the more spinous or rough-skinned and brown varieties of the European species. According to S. S. Flower this toad is very common in the Straits Settlements, hiding by day under stones or logs, or in holes, coming out shortly before sunset, and remaining abroad till dawn; it may be met with on the roads and in the grass, hopping or crawling about in search of ants, bees, and similar food. It utters a rather feeble, plaintive cry when handled for the first time. It can change its colour from light yellowish to dark brown. The spawn, which resembles that of B. vulgaris, may be seen in March and April in ponds, in long strings twined about the water-weeds. The tadpoles are very like those of the common English toad in form, size, colour, and structure of mouth. The largest adult found in Penang measured 115 mm. (about 4 inches) from snout to vent.
B. lentiginosus s. americanus is the common toad of North America, from Mexico to the Great Bear Lake. It is worth noting that this species resembles in its coloration the Eastern races of B. vulgaris, in so far as they generally have a light vertebral line, and frequently dark spots on the under surface. The upper parts are brown and olive, with darker spots, two of which form a chevron behind the eyes. But the tympanum is large, and the male has a subgular vocal sac; the inner metatarsal tubercle is very large, and is used as a kind of digging spur. During the pairing time they take to the pools in great numbers, uttering their music, which consists of a prolonged trill, continued by different individuals, both day and night. Holbrook knew an individual which was kept for a long time, and became perfectly tame. During the summer months it retired to a corner of the room into a habitation which it had prepared for itself in a small quantity of earth placed there for its convenience. Towards the evening it wandered about in search of food. Some water having been squeezed from a sponge upon its head one hot day in July, it returned the next day to the spot, and seemed well pleased with the repetition, nor did it fail during the extreme heat of the summer to repair to it frequently in search of its shower-bath.
Several varieties of this widely distributed species, whose average length is 2½ inches, have been described. The prettiest was called B. quercinus by Holbrook–according to whom it is mostly found in sandy places covered with a small species of oak–which springs up abundantly where pine-forests have been destroyed. It is called the "oak-frog," as it spends most of its time in concealment under fallen oak-leaves, or partially buried in the sand.
B. marinus s. agua is the giant among toads, and is one of the commonest species of the Neotropical region, ranging from the Antilles and Mexico to Argentina. It frequently reaches a length of 6 inches, with a width of 4 inches when squatting down in its favourite attitude. The upper parts are rough, owing to the prominent warty glands, of which the parotoid complex is enormous. The general colour above is dark brown, with sooty dark patches; below whitish, often with blackish patches. This creature appears at dusk, often in large numbers, especially during the rainy season, hopping about, not crawling, with surprising activity. The voice of the male, strengthened by a subgular sac, is said to be a kind of loud snoring bark. The pairing time begins, according to Hensel,[[82]] with the winter rainy season, especially June, and lasts several months, until October, but it is interrupted by the cold, which in the hills of South-Eastern Brazil covers the ponds with ice. Then the tremulous bass voice of the males is heard no longer; they have all withdrawn beneath stones and trees in the neighbourhood of the water. The eggs are laid in strings. The larvae are at first quite black and very small, and the young baby-toads are only 1 cm. in length. They differ considerably from the adult until they are more than 1 inch long; the upper parts are yellowish brown, with darker ocellated patches, each with a light seam, most conspicuous along the sides of the head and back. The under parts are grey, finely stippled with yellow.
Budgett[[83]] remarks that B. marinus feeds on all kinds of insects. "One half-grown specimen sitting by a man's foot picked off fifty-two mosquitoes in the space of one minute, picking them up with the tongue as they settled. The call of this very common toad consists of three bell-like notes; the middle one being the highest. The enormous parotoid glands are discharged like squirts when the creature is roughly handled. When wet weather comes on it hops out from its hiding-place to sit in a puddle, with its head out."
In many species of Bufo the crown of the head forms more or less prominent ridges, especially strong in the region between the eyes; for instance, in B. melanostictus and B. lentiginosus. The skin overlying these ridges is liable to be involved in the cranial ossification, and this reaches its greatest extent in the two Cuban species B. empusus and B. peltocephalus. It is a curious coincidence, to say the least, that such dermal ossifications should be best developed in Neotropical species, in those very countries which amongst the Cystignathidae have produced the abnormal genera Triprion, Calyptocephalus, and Pternohyla. The most peculiar and odd-looking species is Bufo ceratophrys, a native of Ecuador, which has the upper eyelid produced into a horn-like appendage, the two sharply-pointed cones standing out transversely, reminding us of several species of the Cystignathoid genus Ceratophrys; there is also a series of four small pointed appendages on each side of the body. Protective concealment is possibly the reason of these queer outgrowths.
B. viridis s. variabilis, the Green or Variable Toad, reaches a length of about 3 inches, and is the prettiest toad of Europe. The skin is distinctly smooth, the numerous porous, large and small warts being flattened. Parotoid glands are well developed, and a similar pair of glands sometimes occurs on the inner side of the calf, especially in Central Asiatic and in Algerian specimens. The coloration is very variable and changeable. The ground-colour of the upper parts is creamy, with large and small, partly confluent and irregularly shaped spots and patches of green, here and there interspersed with vermilion-red specks, especially along the sides of the back. The under parts are whitish, sometimes spotted with black. The iris is brass-coloured, greenish-yellow, with fine dark dots. The male does not differ from the female in size, but has an internal subgular vocal sac, a conspicuous callosity on the inner side of the first finger, and nuptial brushes on the first three fingers and on the inner palmar tubercle.
The changing of colour affects mainly the intensity of the green; the same individual which now looks almost uniformly dull, almost grey, with dusky olive patches, will, if put into grass and sprinkled with water, within a few minutes appear in a tastefully combined garb of grass-green on a creamy ground. Some Southern and Eastern specimens have a creamy stripe along the vertebral line, thereby closely resembling B. calamita, from which, however, they can always be distinguished by the little pads below the joints of the toes; these pads being single in B. viridis, and double in B. calamita and in B. vulgaris.
The Green Toad spends most of the day in holes, although it is not averse to daylight, and it roams about chiefly in the evening. It can jump well, much better and oftener than the Brown Toad. The food consists strictly of insects of all kinds, and most individuals prefer slow starvation to eating an earthworm. Although continuing to live four or five years in captivity, they do not readily become tame; they are indeed no longer wild, and when handled they no longer emit their peculiar insipid smell, but on being approached they still crouch deeply into the grass, or withdraw into their holes, just as they did when recently caught. The voice is heard during the pairing season, and sounds like the slow creaking of a door, or a combination of a spinning top and rattle. In Germany, during the months of April and May, they take to the ponds, or, improvident like the common frog, to a roadside ditch. The male sits upon the female and grasps her below the arms, his hands on her breast, and in this position they remain for days. The eggs are laid in two strings, twisted around water-plants, and are very numerous. Héron-Royer has calculated them at 10,000 or more in one set. The embryos are hatched, like those of the Common Toad, before the appearance of the external gills and of the tail. In this imperfect condition they remain in the jelly of the egg-strings for a few days, while their external gills sprout out like unbranched little stumps, only to disappear again. In about eight weeks the tadpoles, which reach a length little more than 1½ inch or 40 mm., have metamorphosed and leave the water as baby-toads scarcely half an inch in length.
This species has a very wide range, namely, the whole of Middle Europe excepting the British Isles, France and the Iberian Peninsula; the region between the Elbe and Rhine being its western limit; southwards it extends over all the Mediterranean islands and the north coast of Africa, eastwards through the whole of Russia, Western and Central Asia, not entering India, but spreading along the Himalayas into China. Stoliczka mentions its having been found in the Himalayas at an altitude of 15,000 feet, the highest record of any Amphibian, at least in such latitudes.