DISCOPHORA. 17 
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. 
Fic. 15.—Campanularia. 1. Natural size. 2, Animal magnified: 5S, sac 
containing jelly-bell; ¢@, 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, 1). They vary in size, from the little 
Lucernaria that attaches itself to weeds by a sucking 
disk, to the gigantic Cyanea, that is from two to seven 
feet in diameter, with tentacles over one hundred feet in 
length. 
