Bufonidae 



from the time of laying to find the tadpoles out of the jelly- 

 mass clinging to its outer surface or to nearby waterweeds. (Fig. 

 35.) The rounded head is uppermost, the tail with its thin fin 

 hangs downward. At the place where we should expect the 

 mouth to be, there are two small black elevations, called suckers. 

 (Fig. 210.) These secrete a sticky substance by means of which 

 the young tadpoles attach themselves to weeds or grasses. The 

 jelly-mass is now almost wholly disintegrated and the unfertil- 

 ised eggs are very conspicuous swollen gray-and-white objects. 

 These are masses of foul matter, which should be removed if the 

 tadpoles are developing in a small amount of water under arti- 

 ficial conditions. 



By Thursday the head, body, and tail are still more clearly 

 differentiated one from another, and finger-like extensions from 

 the neck are conspicuous when the tadpole is viewed from above 

 or below. These are the gills for breathing; they have been 

 present fully forty-eight hours, but were so small and delicate 

 that they were very, difficult to see. Ever since the tadpoles 

 emerged from the jelly-mass (which has now totally disappeared), 

 they have moved with a vigorous wiggling of the tail whenever 

 disturbed. Now they are becoming more active and start off 

 on short circuitous voyages when there seems to be no visible 

 disturbance. 



On Friday, when they are a week old, their activity is still 

 greater. The head is apparently much larger, but the gills are less 

 conspicuous than before and seem to be farther back on the 

 neck. The fact is, a membrane is growing backward from the 

 anterior part of the head. This membrane will eventually cover 

 the gills and the neck region, making the tadpole look as though 

 it consisted of a large head and a tail, but no body, because head 

 and body become so thoroughly blended. 1 



On Saturday they are still clinging quietly, except for occa- 

 sional sallies to neighbouring weeds by very circling routes. The 

 gills are wholly covered, except for two minute finger-like ends on 

 the left side. (See Fig. 211.) 



On Monday, the tenth day, we have veritable " pollywogs," 

 as black as tiny coals, with tails that are in a continual wiggle, 

 and small round mouths that are in constant search for something 

 to eat. For the mouths are now open for the first time. These 



1 For details of the development, see Leopard Frog, pp. 176 to 181. 



68 



