166 



AS YS TEMA TIC ZOOLOG Y. 



In these jelly fishes (fig. 14, m) branches of the digestive 

 tract run to the margins of the umbrella, where they 

 connect with a ring canal which runs around its rim near 



FIG. 14. A Hydroid (Beugcrinvilleq). After Allman, from Lang, h, hydranth; 

 mk, medusa-buds; m, a free-swimming medusa. At the base are seen the 

 root-like stolons connecting the colony together. 



the bases of the tentacles. These hydrozoan medusae can 

 be recognized by having the opening of the bell partially 

 closed by a thin membrane (velwri) shown in the figure. 

 These medusae separate from the colony and swim freely 

 through the water, and they produce eggs from which 

 are developed other colonies. 



Here is a point which needs emphasis. From the egg is 

 developed a hydranth which by budding gives rise to 



