HYDROIDEA. 



403 



FIG. C96. 



Sertularia. 



FIG. 697. 



Tubularia. 



m, medusae ; ct, coronal ten- 

 tacle; p, proboscis. 



Campanularia. The hydro-medusne in the 

 bell-shaped cups drop out and become free 

 medusae similar to Fig. 698. 



FIG. 698. 



In the Sertulariana (Fig. 696) and Campanularians, the 

 hydroid has a stem which is covered by a 

 horny sheath, which is formed into few or 

 many bells or cups. In a fertile cup there 

 are hydro-medusae, which at length drop out 

 and become free medusae similar to Tiarop- 

 sis (Fig. 698). 



In the Siphonophoree the hydroid acalephs exist as free 

 communities, each community being made up of individ- 



Tiaropsis. 



