514 



RADIATES I ACALEPHS. 



able as a bubble, yet they perform varied and rapid move- 

 ments, contract and expand their tentacles, catch and vo- 



F - p. 



rackxisly devour medusae of their own kind or those of 

 other species, and other marine animals. They may be 

 seen in the spring, and in great numbers ; about the 

 middle of summer they lay their eggs and perish. But 

 these eggs, as already noticed, do not hatch medusae, like 

 die parents ; but each hatches a little hydroid. which is first 

 free, then afterwards becomes attached to a shell, or sea- 

 weed, or stone, and from this hydroid other hydroids bud 



