HYDROIDS. 



233 



expand into genuine medusae or jelly-fishes. Figure 

 478 shows a little cluster of Hydroids attached to sea- 

 weed, and Figure 479 shows a single individual of the 



Fig. 478. Coryne. Cluster of Hydras grow- 

 ing on sea- weed. 



Fig. 480. Coryne. Adult. 



Fig. 479. Single individual of Fig. 478, 

 enlarged, showing a and b just ready to 

 drop off and become free medusas, like Fig. 

 480 ; c, a younger bud. 



same very much magnified, with two of the buds much 

 enlarged, and a third quite prominent. Soon each bud 

 becomes detached, and floats away as a free jelly-fish, 

 like Figure 480, and is then known as Coryne, or, as 



