Encyclopædia Britannica, Ninth Edition/Toad

moment of extrusion, as in the frog, the parents resorting to the water for the purpose of reproduction. The ova are laid in spring, and are arranged, not in shapeless masses, but in a string containing a double series of eggs adher ing by their gelatinous envelopes; the string extends to a length of three or four feet. The tadpoles are similar to those of the frog, but blacker; their metamorphosis takes place in the same manner, the three pairs of external gills being first absorbed and replaced for a time by internal gills, which are in their turn lost, the branchial slits being closed by the coalescence of the opercular membrane with the skin. The metamorphosis is complete in autumn. The toad is carnivorous, feeding on flies and other insects and worms. It hibernates in winter, passing its period of torpidity in holes or burrows in the earth. The finding of toads in a state of hibernation has given rise to stories of their being found in the centre of trunks of trees or imbedded in solid rock. The myth of the jewel in the head (Shakespeare) is probably founded on the brightness of the eyes, in which the iris is flame-coloured. There are two kinds of toad in Britain, the Common Toad, which is almost black in colour, and the Natter-jack Toad, which is lighter, smaller, and has a bright yellow line along the middle of the back. The length of the common toad is 3| inches, of the natter-jack 2f inches. The male natter-jack possesses a bladder or vocal sack beneath the throat communicating with the mouth, which acts as a resonator to its voice; its cry is " gluck-gluck." The vocal sack is absent in the common toad, and only in completely developed in the Green Toad of the Continent.

In zoological classification the toad belongs to the genus Bufo, first constituted by Laurenti in the Synopsis Reptilium, of which the fol lowing diagnosis is given in the Brit. Mus. Cat. Batr. Sal., 1882: Pupil horizontal. Tongue elliptical or pyriform, entire and free behind. Vomerine and maxillary teeth none. Tympanum dis tinct or hidden, seldom absent. Fingers free; toes more or less webbed; the tips simple or dilated into small disks. Outer metatarsals united. Omosternum generally missing; if present cartila ginous; sternum a cartilaginous plate, sometimes more or less ossified along the median line. Diapophyses of sacral vertebrae more or less dilated. Terminal phalanges obtuse or triangular. Distribution cosmopolitan, except Australia.

Bufo vulgaris, Laurenti, the Common Toad, is thus distinguished. Crown without bony ridges. First finger as long as or longer than the second. Parotids distinct. Tympanum smaller than the eye. Toes hall webbed; no tarsal fold; subarticular tubercles of toes double. The species is widely distributed, occurring throughout Europe, Asia, and north-west Africa.

Bufo calamita, Laurenti, the Natter-jack Toad, shows the follow ing differences from B. vulgaris: toes not half webbed; tympanum rather indistinct; a tarsal fold. It is distributed throughout Europe.

According to Boulenger there are 77 species of Bufo known, of which 35 are confined to the Old World, the rest to the American continent. No species is common to the two great continents. The only other species occurring in Europe besides the two which are found in Britain is Bufo viridis, Laurenti, which, ranges through out Europe, Asia, and North Africa.