544 TEXTBOOK OF ZOOLOGY 



toads have poor vision, due to the lack of accommodation in the 

 eye, the toad appears to see better. Toads also retain sound im- 

 pulses longer than do frogs. Sound is of greater importance to the 

 toad, for in his terrestrial hunting ground he is dependent to a 

 large extent on sound in locating insect food. 



Embryology 



The eggs pass continuously through the oviduct with the result 

 that they are laid in long strings or tubes of albuminous jelly. The 

 egg mass is laid underwater, and the toad moves around during 

 the egg laying process with the result that the strings may be con- 

 siderably tangled around submerged vegetation. Shallow creeks 

 provide a favorite breeding ground. 



The length of time taken for the eggs to develop and hatch de- 

 pends upon the temperature. They usually hatch in from two to 

 four days. The tadpoles may transform into young toads in from 

 30 to 60 days after hatching. They measure % to % of an inch 

 at this time. 



Toad tadpoles are black. Usually toad tadpoles can be distin- 

 guished from frog tadpoles by the position of the anus. The anus 

 in toad tadpoles is median, while in frog tadpoles it is somewhat 

 on the right side. The spiracle of toad tadpoles is very small and 

 is on the left side. 



