318 VENOMS 



Toads &re 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 Cloez.^ 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 VAcademie des Sciences, April 21, 1851, and May, 1852. 



