180 THE ADVENTURES OF 



when the time of their metamorphosis arrives, this skin will 

 split all down their back, and a little frog will come out of 

 it. Look at this tadpole I have just caught; you can see 

 the feet through its transparent skin. To-day it is a fish, 

 that is to say, it bi'eathes through gills those little tufts 

 you see on each side of its head and perhaps to-morrow it 

 will undergo that metamorphosis which will cause it to 

 breathe through its mouth. The Toltecs, the great nation 

 which preceded the Aztecs in Mexico, counted the frog 

 among their gods." 



When putting the tadpole back into the pool, I noticed 

 some whitish insects, which were incessantly rising in jerks 

 to the surface of the water, and diving down again direct- 

 ly. Lucien, astonished at their movements, cried out 



" But, papa, they are walking on their backs !" 



" You are quite right ; they are hydrocorises, allied to 

 the tettigones, and consequently hemipterce." 



The young naturalist was more successful than in his 

 gyrin-hunting, and succeeded in catching two or three of 

 these water-bugs. 



" What is the use of their wings ?" he inquired. 



" Why, to fly with, and to move from place to place." 



" Then water-bugs are really able to fly, swim, and walk ?" 



" Yes ; and I'm sure they can see in the dark, too," said 

 1'Encuerado, who, it may be remembered, envied animals 

 this privilege. 



"We are certainly justified in thinking so," I answer- 

 ed, smiling, " for they nearly always choose the night for 

 travelling. Take care they don't bite you, for the water- 

 bug bites as hard as its kinsmen of the woods and houses." 



A little farther on, Lucien stopped in front of an herba- 

 ceous plant, covered from top to bottom with round, flat 

 black insects, speckled with red, and almost resembling mo- 

 saic-work. He was very proud of his beautiful discovery, 



