FROGS 87 



Anodonta, the freshwater mussel, has a peculiar life history. 

 The larvae hatch inside the parent, and remain there until the 

 end of the summer. They are then ejected, or perhaps leave 

 on their own account, and swim about until they happen 

 to meet a member of the pisces (fish) ; no sooner have they 

 touched their unlucky host than they hold on to the best of 

 their abilities, and remain until mature. Strangely enough, 

 not only are they carried about by the fish, but also its skin 

 grows so as to cover the parasitic mollusc, thus preventing it 

 from dropping off should an accident occur. 



Snails' eggs are so frequently found that they deserve men- 

 tion. Molluscs are hermaphrodites that is to say, both male 

 and female in the same individual. On two snails meeting a 

 peculiar battle takes place. In a sac kept for the sole and 

 special purpose a number of darts are kept, and on this aus- 

 picious occasion they are fired at each other by the molluscs. 

 What the use of this conduct may be is difficult to say, as it 

 hardly seems affectionate to hurl darts on such a trivial pre- 

 text ; when this preliminary battle is over the two snails join 

 together. It is interesting to know that one snail is tem- 

 porarily male, whilst the other is temporarily female. The eggs 

 are laid on sticks, stones, weeds, or the glass of the aquarium, 

 in long jelly-like masses. The u time being " male, his work 

 accomplished, now changes into a temporary female, and sub- 

 sequently meets some other snail of the opposite sex, which 

 will later in the season become a female. 



CHAPTER X 



FROGS 



A BOOK on pond life would hardly be complete unless some 

 pages were devoted to frogs and newts. Few people care to 

 keep frogs except in a conservatory. Their incessant croaking, 

 especially during the night, is far from pleasant, and owing to 

 their surprising agility, sooner or later one or more frogs are 

 certain to evacuate their home and perambulate the house, 

 much to the horror of the gentler members of the household. 

 How they have managed to escape is often a difficult question 

 to solve. 



The life history of the frog is of particular interest, because 

 the young are so very different to the adult. It is hard to 



