152 THE INDUSTRIES OF ANIMALS. 



{Cottus gobid) of our rivers, which spawns in the Seine 

 in May, June, and July, acts in this manner. Beneath 

 a rock in the sand it prepares a cavity ; then seeks 

 females and brings them to lay eggs in its little 

 lodging. During the four or five vi^eeks before they 

 come out it watches the eggs, keeping away as far as 

 possible every danger which threatens them. It only 

 leaves its position when pressed by hunger, and as 

 soon as the hunt is concluded, returns to the post of 

 duty. 



Other animals when digging have a double object ; 

 they wish to shelter themselves, and at the same time 

 to find the water which they need for themselves or 

 for the development of their young. 



It is well known that Frogs and Toads generally go 

 in the spring to lay their eggs in streams and ponds. 

 A Batrachian of Brazil and the hot regions of South 

 America, the Cystignathiis ocellatus, no doubt fearing 

 too many dangers for the spawn if deposited in the 

 open water, employs the artifice of hollowing, not far 

 from the bank, a hole the bottom of which is filled by 

 infiltration. It there places its eggs, and the little 

 ones on their birth can lead an aquatic life while 

 being guaranteed against its risks. 



A terrestrial Crab, the Cardisoina carnifex, found 

 in Bengal and the Antilles, acts in the same manner ; 

 but in this case it has in view its own convenience 

 and not care for its offspring. Its habitat is especially 

 in low-lying spots near the shore, where water may 

 be found at a trifling depth beneath the soil. To 

 establish its dwelling, the Crustacean first buries itself 

 until it reaches the liquid level. Arrived at this point, 

 it makes a large lair in the soft soil, and effects com- 

 munication with the outside by various openings. It 



