422 CLASS REPTILIA. 



manders, in which this organ resembles a bladder ; the tra- 

 chea is always very simple ; there is no epiglottis nor inferior 

 larynx. Respiration is carried on by the muscles of the 

 throat, which perform the office of the diaphragm, an organ 

 not existing in these animals. For the inspiration of air, it 

 is necessary that the mouth should be closed, so that a frog 

 or toad, placed in the water, and the mouth kept forcibly 

 open, would perish immediately. The majority of the batra- 

 cians, however, have a voice which is termed croaking, which 

 is produced by means of certain air-sacs, or extended mem- 

 branes, on which the air expelled from the lungs impinges 

 and vibrates. 



Linnaeus comprehended the major part of the animals of 

 this order in his genus rana. The salamanders he placed 

 among the lizards ; of the siren, that great naturalist formed 

 his order Meantes, which subsequent naturalists rejected ; 

 and in Dr. Turton"'s Linnaeus, the siren forms a separate genus 

 after lacerta, and before the serpents. 



We shall commence our more peculiar investigation of the 

 batracians with the genus rana, taking first the frogs, pro- 

 perly so called. 



There is so great a relation between the first three sub- 

 divisions of the batracians, that so far from blaming Lin- 

 naeus for having united them together at the time in which 

 he wrote, we cannot think that he could reasonably have 

 done otherwise. Many species are, indeed, sufficiently well 

 distinguished by their characters ; but many others are so 

 little so, that it is a matter of some difficulty to determine 

 where they should be placed. It is principally in the species 

 of toads and frogs that this uncertainty exists, for the sub- 

 division of the hylae is much more neatly characterized. 



" This great resemblance to ignoble beings," (says Count 

 Lacepede, in the true spirit of a Frenchman,) " is a great 

 misfortune. The frogs conform in external appearance so 



