ALTERNATE GENERATIONS. 



259 



brilliant crested float. In this curious Acale- 

 phian Hydroid, or Physalia, the individuality of 

 function is even more marked than in the Hy- 



Physalia, or Portuguese Man-of-War. 



dractinia. As in the latter, some of the indi- 

 viduals are Medusae-bearing, and others simple 



