1911 Encyclopædia Britannica/Toad

From Wikisource
Jump to: navigation, search

TOAD, a name commonly applied in contradistinction to "frog," to tailless batrachians of stout build, with more or less warty skin. Thus, of the two closely related discoglossid genera Bombinator and Discoglossus, the former is called a toad and the latter a frog. But the true toads are the Bufonidae. arci- ferous batrachians with dilated processes to the sacral vertebra and without any teeth in the jaws. The type of the family is our common toad, Bufo vulgaris, and round it cluster a large of number of species of the same genus, and the smaller genera; Eupemphix, Pseudophryne, Nectophryne, Nectes, Notaden, Myo- batrachus, Rhynophrynus and Cophophryne. That the shape of the body is not a safe guide in judging of the batrachians is shown by certain species, such as Bufo jerboa, which in its slender form and extremely long limbs surpasses the typical frogs, while on the other hand, some true frogs (Rana'), adapted to burrowing habits, are absolutely toad-like.The Bufonidae include terrestrial, burrowing, thoroughly aquatic and arboreal types; Rhinophrynus, of Mexico, might be described as an ant- eater.

The genus Bufo embraces about 100 species, and is repre- sented in nearly every part of the world except the Australian region and Madagascar. Two species are found in the British Isles: the common toad, Bufo vulgaris, and the natterjack, Bufo calamita. The former is found almost everywhere; the second, which differs in its shorter limbs with nearly free toes (which are so short that the toad never hops but proceeds in a running gait) and it usually possessing a pale yellow line along the middle of the back, is local in England, the south-west of Scotland, and the west of Ireland; it is further remarkable for the very loud croak of the males, produced by a large vocal bladder on the throat which, when inflated, is larger than the head. Toads lay their eggs in long strings, forming double files in straight jelly-like tubes.

A small toad, Pseudophryne vivipara, recently discovered in German East Africa, has proved to be viviparous, this being the only such instance known among tailless batrachians.