214 



EVENINGS AT THE MICEOSCOPE. 



confined to the, base. These minute creatures, in this 

 early state of their existence, are natatory and wonder- 

 fully active. They are continually swimming from one 

 part of the vessel to the other, and when observed free 

 in their native pools, arc, if possible, even more active 



SECOin) 6TAGE OF eaOEE-CEAE. 



than when in confinement. Their swimming is pro- 

 duced by continued flexions and extensions of the tail, 

 and by repeated beating motions of their claws ; this, 

 together with their grotesque-looking forms, gives them 

 a most extraordinary appearance when under examina- 

 tion. As the shell becomes more solid they get less ac- 

 tive, and retire to the sand at the bottom of the vessel, 

 to cast their shells, and acquire a new form. They are 



