THE DISCOPHOEES, OE LAEGE MEDUSA. 
129 
also found a refuge in the tangle of interlacing threads. 
Commensalism, which is comparatively a new subject, would 
seem to have a wide range in the animal kingdom. 
A few words may suffice for the economic uses of the 
Discophores, which seem to be of the smallest. The old 
doctors found healing virtues in them, and used them as 
medicines, with probably as much success as many of their 
drugs. They have been carted as manure, in ignorance of the 
fact that the solid matter of a jelly-fish weighing many pounds 
is represented, when the water is evaporated, by a few grains 
of film. Somebody has undertaken to extract ammonia from 
them ; and Mr. Arthur Adams has seen the Chinese “ cut off 
huge slices of the firm translucent jelly” of a stranded 
Cyancea as a relish for the evening meal. 
Their best use, after all, is that to which the philosophic 
naturalist puts them.* 
DESCRIPTION OF PLATE LXX. 
Fig. 1. 
» 2 . 
Figs. 
The ovum of the Discophore, with germinal vesicle and spot. 
The planula or embryo. 
The embryo attached — the cilia still remaining j a, the horny 
sheath. 
The polypite. 
A polypite dividing transversely. 
The same, showing the segments in a more advanced condition, 
and already exhibiting a medusan form $ x, the new wreath of 
tentacles. 
The polypite bearing a single Medusa-bud ; the rest of the pile 
having become free. 
The young Medusa shortly after detachment. 
The same, showing the lobes and eyes. 
Pelagia cyanella (Peron and Lesueur), adult. This Medusa is 
produced directly from the egg without the intervention of a 
polypite stage. 
6 and 8 are after Van Beneden ; the rest are after Agassiz. 
* No space is left me for the aberrant group of Lucemariidce, which are 
Jixed Medusce , producing their like without the intervention of a polypite. 
