TENTH ANNUAL REPORT. 153- 



Pond Frog {R. clam at a) live about two years in a larval state. 

 The Wood Frog {R. sylvatica), a terrestrial species, undergoes 

 its metamorphosis within the course of a single warm season. 

 Though the latter species transforms from tadpole to perfect ani- 

 mal in a much shorter time than the semiaquatic frogs, it is quite 

 tardy as compared with the Toad (Bufo). Strictly terrestrial, 

 except during the breeding season, the latter creature completes 

 its transformation, from the appearance of the egg to the fully 

 developed land animal, within two months. The tadpoles of the 

 toads never reach any but a diminutive size, and the young ani- 

 mal is very small. With the semiaquatic frogs the tadpole may 

 grow to a length of six inches. The difference in size between 

 these land and amphibious species is clearly shown in the photo- 

 graphs. 



It appears that Nature has hastened the transformation of the 

 terrestrial species as a matter of necessity. They lay their eggs 

 in temporary bodies of water, left by the spring freshets and rains. 

 Such pools evaporate during the summer. The aquatic species 

 deposit their eggs in the permanent bodies of water about which 

 they lurk. Moreover, the ponds and streams fed by permanent 

 sources are colder than the ditch or lowland pool selected by the 

 toad, and temperature plays an important part in the growth of 

 the batrachian larva. 



The greater number of frogs and toads have an intense fear of 

 snakes. A brown snake {Storcria), barely larger than an earth- 

 worm, will cause a bulky pond frog or a big toad to cringe, point 

 its snout downward, then puff up prodigiously. INIost of the 

 bull frogs in the Reptile House exhibit quite different habits. 

 If a snake of moderate size (about one and a half feet long) be 

 placed in their cage it is seized at once. Despite its struggles 

 it is drawn into the capacious interior of the frog, partly by 

 the muscular action of the throat and partly by repeated grasp- 

 ings of the forefeet. When placed in a cage containing several 

 striped snakes one of these voracious frogs exhibited abso- 

 lutely no fear, but gorged himself to the limit of his very 

 elastic capacity. 



During the summer months the collection of frogs and toads 

 is supplied with an abundance and variety of food that as far as 

 possible corresponds to what such creatures obtain in a wild 

 state. Each day a keeper is assigned to " sweep " the meadows 

 bordering the aquatic mammals pond for an hour or more. This 

 man is provided with several glass jars and a large sweeping net. 

 consisting of a stout iron ring, on a short handle, provided with 



