318 VENOMS 
Toads are easy to distinguish from frogs owing to their squat 
and clumsy shape, and to the mass of glands with which each 
side of the neck and a more or less extensive portion of the body is 
furnished in these animals. According to G. A. Boulenger, the 
number of known species amounts to seventy-six, which are found 
in the Old and New Worlds, but have no representatives in 
Australia. The species that are the most common, and most 
interesting from the point of view of their venoms, are :— 
The Common Toad (Bufo vulgaris), in which the skin, which is 
very thick and rugose, is covered on the back with large rounded 
tubercles with reddish summits. This species is a great destroyer 
of insects, and, as such, is very useful to agriculturists. 
The Natter-Jack (Bufo calamita), in which the digits are 
palmate at the base. When irritated it contracts its skin and covers 
itself with a white frothy exudation, which gives off an odour of 
burnt powder. 
The Green Toad (Bufo viridis), which is especially abundant in 
Southern Europe, the Levant, and North Africa. 
The Musical Toad (Bufo musicus), a species distributed through- 
out North America as far south as Mexico, and in which the back is 
covered with pointed conical tubercles resembling spines. 
The Brown Pelobates (Pelobates fuscus), common in the neigh- 
bourhood of Paris, the skin of which is almost entirely smooth. 
Although it appears to be nearly destitute of glands, this animal 
secretes a very active venom, which has a penetrating odour and 
kills mice in a few minutes, producing vomiting, convulsions, and 
tetanic spasms of the muscles. 
The toxicity of the venom of toads was long ago demonstrated 
by the experiments of Gratiolet and Cloéz.' It is manifest only in 
the case of small animals, and in man merely produces slight 
inflammation of the mucous membranes, especially of the con- 
junctiva. 
! Comptes rendus de l'Académie des Sciences, April 21, 1851, and May, 1852. 
