DISCOPHORA. ij 



The Monocaulus is a gigantic Hydroid, seven feet high, 

 and nine inches across the expanded tentacles, living in 

 the Atlantic at a depth of four miles below the surface. 

 Many of the so-called mosses that are common on the 

 shore, and are pressed as sea- weed, are in reality compound 

 Hydroids enclosed in horny cells, as the Plumularia. 



FlG. 15. Campanularia. i. Natural size. 2. Animal magnified : S, sac 

 containing jelly-bell ; a a, animal feeding. 3. Free-swimming young, 

 magnified. 3', natural size of jelly-bell. 



Order II. Discophora. We now come to jelly- 

 fishes that are developed directly from eggs, as Pelagia 

 campanella, or, as in Aurelia, produced from a Hydra 

 form (Fig. 17, i). They vary in size, from the little 

 Lucernaria that attaches itself to weeds by a sucking 

 disk, to the gigantic Cydnea, that is from two to seven 

 feet in diameter, with tentacles over one hundred feet in 

 length. 



