HYDROZOA. 



61 



bells, medusa-like individuals, each consisting simply of an umbrella, Case 3, 

 and adapted solely for swimming ; next follows a whorl of leaf-like Upright part. 



Fig. 24. 



Floating colonies of iS/p^onop/iora. a. Diphye$ campanulata. B. A group 

 of appendages from the stem of Diphyes. c (Fig. on right). Physophora 

 hydrostatica. d. Swimming-bell of the same. e. Cluster of generative 

 buds (degenerate mcdusse) of Agalma. a, stem of colony ; a', air 

 sac; m, swimming-bell; c, concavity of same; v, radial canals; 

 0, orifice of umbrella ; t, covering pieces in b, tentacle-like polyps in c ; 

 «, stomach ; i, tentacles ; g, generative buds. (After Gegenbaur, from 

 Encyc. Britannica.) 



" covering-pieces," and below this a cluster of medusa-like generative 

 polyps, tentacle-like polyps and short-stalked feeding polyps, each of 



