THE LUCERNARIDA. 351 
and pigment-spots, here united into a single organ, termed the 
lithocyst, are each protected externally by a sort of hood, whence 
these jelly-fishes have been named “ Stegonophthalmia,” or 
*‘ covered-eyed,” by Forbes, to distinguish them from the 
naked-eyed * Gymnophthalmia,” or Meduside. The Pelagide 
(Clirysaora), which form one of the divisions of this group, are 
simple, and have their margin surrounded with tentacles like the 
Merlusidze, while the Rhizostomide have no marginal tentacles, 
and consist of numerous polyps studding the trunks of a de- 
HU 
Oceanic forms of Lucernaride. 
a. Rhizostuma pulmo. 6. Chrysaora hysoscella. c. Its hthocyst.—(All reduced.” 
pendent tree. These animals have consequently no central 
mouth, but hundreds of little mouths all active for the welfare 
of the community. 
The sessile Lucernaride differ from the other members of 
the order by the narrow disc or stalk which serves to fix their 
body when at rest. Their quadrangular mouth is in the centre 
of the umbrella expansion, and round the margin of the 
cup arise a number of short tentacles, disposed in eight or nine 
tufts in Lucernaria, and forming one continuous series in 
Carduella. 
