64 CLASS III. REPTILES. ORDER IV. BATRACHIA. 



long and slender bodies without limbs, and by the great ex 

 tensibility of their jaws, mouth, and throat, which enables 

 them often to swallow animals of greater diameter than them- 

 selves. They are always provided with teeth, which are 

 sharp and bent backwards. 



They are divided, as is well known, into the venomous and 

 those that are not venomous. The number of the latter kind 

 is the x greatest, and includes the largest animals. Among 

 them are the great Boa constrictor, the Aboma, and the Ana- 

 conda, which sometimes attain the length of thirty or forty 

 feet, and inhabit marshy and fenny places in the tropical 

 parts of America. They attach themselves by the tail to the 

 branches of trees, leaving their bodies swinging in the air, 

 in order to seize upon animals approaching them, which they 

 generally swallow whole. The Ular Sawa, or the great Py- 

 thon, is another serpent of the same kind and size, and in- 

 habits the ancient continent. The smaller and less celebrated 

 species are very numerous, and are distributed over every part 

 of the earth. 



The venomous serpents are generally armed with fangs, for 

 the specific purpose of infusing poison into the wounds they 

 inflict. These fangs are situated in the upper jaw, and per- 

 forated by a small canal, which, opening on their extremities, 

 gives passage to a fluid, secreted by a gland under the 

 eye. When the tooth pierces the flesh of any animal, a por- 

 tion of this fluid is injected into the opening, and produces 

 eifects more or less dangerous, according to the virulence of 

 the poison and the kind of animal wounded. When broken 

 or injured, these fangs are renewed, and when not employed, 

 are hidden from sight by a fold or projection of the gum. 

 The largest and most celebrated of these animals- is the rat- 

 tlesnake of America. It is so called from a peculiar instru- 

 ment at the end of its tail, denominated its rattle, which pro- 

 duces a slight rustling sound, when it is shaken, and is 

 intended to give warning of the animal's anger. This and 

 the other venomous serpents are not malignant or ferocious 

 in their dispositions, and soldom make use of their poison 

 unless provoked. 



IV. Batrachia. The reptiles of this order have only one 

 auricle to the heart, into which the veins from the lungs and 

 from the body both enter. In it are included the toad, frog, 

 salamander, and other similar animals. They are principally 

 remarkable for a transformation which takes place in their 

 offspring after leaving the egg. When first hatched, they 



