30 BATEACHIANS. 



In the meantime tte respiratory cavity is formed, the communicat- 

 ing duct advances with the elongation of the oesophagus, and at 

 the point of communication the larynx is ultimately developed. 

 The lungs themselves extend as simple elongated sacs, slightly re- 

 ticulated on the inner surface backwards into the abdominal cavity. 

 These receptacles being formed, air passes into and expands the 

 cavity, and respiration is commenced, the fore limbs are liberated 

 from the branchial chambers, and the first transformation is 

 accomplished. 



The alleged venemous character of the Common Toad has been 

 altogether rejected by many naturalists ; but Dr. Davy found that 

 venemous matter was really contained in follicles in the true skin, 

 and chiefly about the head and shoulders, but also distributed 

 generally over the body, and on the extremities in considerable 

 quantities. Dr. Davy found it extremely acrid, but innocuous 

 when introduced into the circulation. A chicken inoculated 

 with it was unaffected, and Dr. Davy conjectures that this acrid 

 liquid is the animaPs defence against carnivorous Mammalia. A 

 dog when urged to attack one will drop it from its mouth in a 

 manner which leaves no doubt that it had felt the effects of the 

 secretion. 



In opposition to these opinions the story of a lad in France is 

 told, who had thrust his slightly wounded hand into a hole, intend- 

 ing to seize a Lizard which he had seen enter. In place of the 

 Lizard he brought out a large Toad. While holding the animal, 

 it discharged a milky yellowish white fluid which introduced itself 

 into the wound in his hand, and this poison occasioned his death ; 

 but then it is not stated that the boy was previously healthy. 



Warm and temperate regions with abundant moisture are the 

 localities favourable to all the Batrachians. Extreme cold, as 

 well as dry heat, and all sudden changes are alike unfavourable 

 to them. In temperate climates, where the winters are severe 

 they bury themselves under the earth, or in the mud at the bottom 

 of pools and ponds, and there pass the season without air or food, 

 till returning spring calls them forth. 



The species of this family are very numerous. MM. Dumeril 

 and Bibron state that the Frogs, Rana, number fifty-one species ; 

 the Tree Frogs, Hyla, sixty- four ; and the Toads, Bufo, thirty-five. 



