220 THE INFANCY OF ANIMALS 



keeps careful guard over the family, which may number 

 twenty or thirty individuals, at a short distance from 

 them. When alarmed for their safety a swift move 

 is taken towards them : they then collect around their 

 parent's mouth as though at the word of command. 

 Suddenly, if the cause of alarm be not removed, the mouth 

 is opened and the whole swarm is engulfed. In an adult 

 captured while thus laden the young were found crowded 

 together with their heads towards the gills. When the 

 cause for alarm is past the youngsters are probably 

 suddenly expelled from their living cavern. 



Among the frogs again, it will be remembered, there 

 are several species which carry either the eggs or young, 

 and sometimes both, in pouches. It is therefore the more 

 interesting to note that the fishes furnish us with similar 

 cases. Thus the eggs of the pipe-fish and its kind are 

 carried in a pouch at the base of the under surface of the 

 tail. Here they hatch, and for some time after the young 

 have left this queer nursery they are said to seek its 

 shelter on occasions of danger. 



We must pass now to speak of certain cases where the 

 young are sheltered during the earlier phases of this 

 development within the body of the parent — a device, 

 so to speak, which has been adopted by species in no way 

 related one to another. The number of species in which 

 the young are thus provided for is so large, and they 

 display so close a likeness, that for our present purpose 

 it were profitless to do more than cite one or two of the 

 more interesting cases. 



In Cymatogaster aggregatus, one of the surf perches 

 (Embiotocidte), a fish too little known to have earned a 

 popular name, the young, which range from three to 

 twenty, according to the size and age of the mother, lie 



