264 THE STUDY OF ANIMAL LIFE CHAP, xn 



a miniature of the adult. There are other interesting 

 modifications in the life-history of freshwater forms, 

 witness the little larvae (Glochidia) of the freshwater 

 mussels which are kept within the gills of the mother 

 till the approach of a minnow, stickleback, or some other 

 fish, to which the liberated young then fix themselves. 

 After sojourning for a time on the fish, the young mussels 

 undergo a metamorphosis and drop off to begin an in- 

 dependent life, often far from their birthplace. 



