ORDER BATRACHIA. 455 



the sun on toads, and we are informed by Adanson, that 

 the evaporation from the skin of these animals is so great, 

 that the negroes in traversing the burning sands of Senegal, 

 are in the habit of applying one of them alive to the fore- 

 head, for the purpose of cooling it. 



The sense of touch must be delicate in these animals, from 

 the nakedness of the toes, which are without claws. 



The point of the tongue is not bifurcated, as in most 

 of the frogs. 



The length of the intestines to that of the body is in the 

 proportion of two to one. The rectum is cylindrical. 



The structure of the heart is the most simple imaginable. 

 There is but one rounded auricle, wider than the basis of the 

 heart, and strengthened by fleshy columns ; and there is but 

 a single conical ventricle, whose cavity has fleshy columns 

 adherent to it, and opens into the common trunk of the 

 arteries by a single orifice below the auriculo-ventricular 

 aperture. 



The aorta is soon divided into two branches, each of which 

 produces a pulmonary, a common carotid, an axillary, and a 

 vertebral artery. Then they approach one another and 

 unite into a trunk, which furnishes the coeliac and all the 

 other arteries of the abdominal aorta. In this manner a part 

 of the blood only passes into the lungs. The veins have a 

 similar distribution. 



The toads do not possess the sonorous vesicles which are 

 in the mouth of the male frogs, and which give to their 

 croaking its resounding noise. 



The toads, like the other batracians, have no generative 

 organs of intromission. 



The young, on quitting the egg, have the head and belly 

 united in a spherical mass, and terminated by a fish-like tail. 

 Their metamorphoses are similar to those of frogs. The 

 eggs acquire a marked development in the ovaries, and 



