The Common Bullfrog 



will always sing when other sounds are being produced, whether 

 these are musical or not. He always becomes enthusiastic at 

 the sound of running water. 



The Bullfrog has two internal vocal sacs, which act as 

 resonators. These are in the pouch of the throat, and the open- 

 ings into them are on the floor of the mouth. (See Fig. 279.) 

 When the frog croaks, the yellow throat over the vocal sacs, 

 and the sides of the body in the region of the lungs, are forcibly 

 distended with air drawn in through the nostrils. Throat and 

 sides immediately relax as the air passes out over the vocal 

 cords of the throat and the sound is produced. 



The frog's vocal powers do not stop with the croaking de- 

 scribed. If we live in the country, or if we are given to camping 

 and fishing, it is possible that at least once in a lifetime we shall 

 hear this species of frog give voice to quite another sound. This 

 comes when he is forcibly seized by a huge enemy, such as a hawk 

 or an otter. The unexpected sound given at such a time is most 

 distressing to hear. It is a loud, prolonged, high-pitched scream, 

 containing anguish and antagonism, to such an extent that we 

 cannot but think that the cry is made by the human voice. 

 Sometimes, when we take into our hands a masterful, untamed 

 Bullfrog, just brought from the pond, he gives this same cry 

 with wide-opened mouth. The scream of distress is so penetrat- 

 ing, and so prolonged, that we hasten to release the frog, for 

 fear our neighbours will accuse us of cruelty to children. 



However, as the mouth is held wide open while the cry is 

 given, we find a most excellent opportunity to see various things 

 about which we may have been curious. (Fig. 279.) The 

 tongue has a forked posterior end, and has its front end fastened 

 just back of the lower lip.^ There is a circle of small, sharp 

 teeth on the upper jaw. Two large openings at the sides back 

 of the tongue lead into the vocal sacs. Two smaller openings 

 on the roof of the mouth are the openings of the tubes leading 

 from the nostrils. Their situation so far in front of the throat 

 makes it clear why it is that the frog must swallow the air that 

 passes in at the nostrils in order to get it down to the lungs. 

 The great rounded elevations on the roof of the mouth are made 

 by the eyes. These extensions from the roof of the mouth 



1 See description of toad's tongue, p. 8i. 



