760 
ROBERT PAYNE BIGELOW 
THE ADULT CHRYSAORA 
Turning now to the fully formed adult, figs. 2 to 10 (fig. 1 is 
not fuU}^ adult), we find no structure not represented in the stage 
just described, but there are marked changes in form and propor- 
tion and there is much greater histological differentiation. 
The size of the animal and of all of its parts has greatly in- 
creased, the general ectoderm and endoderm have become more 
marked, the cells being thicker in proportion to their width, the 
nettle cells and gland cells are fully developed, and the general 
topography in the region of the sense-organ is very much height- 
ened, fig. 2. 
On looking down upon the upper side of the umbrella, one 
notices in the hood covering each rhopalium an elliptical area free 
from the nettle batteries that now form thickly set mounds over 
the rest of the surface. These elliptical areas are the dorsal sen- 
sory grooves, an early stage of which has just been described. 
Each groove on closer examination is seen to be now a funnel- 
shaped cavity, the apex of the funnel extending deep into the 
mesogloea to a point opposite the base of the rhopalium, fig. 6. 
At the edges of the groove the common cuboidal epithelium of 
the exumbrella grades into a deep columnar epithelium that lines 
the groove. The cells of the epithelium are many times deeper 
than they are wide and are ciliated, and at the base of the layer 
next to the mesogloea there is a thin stratum of nerve fibers. This 
epithelium is probably of that kind of sensory epithelium com- 
mon to jelly fish which has been carefully described and figured 
by Eimer (77), Claus (77), the Hertwigs (78), and Schewia- 
koff ('89). There are present some mucous gland cells like those 
found by Wilson ('88) in Manicina. The mucus granules stain 
so deeply with haematoxylin that the mass of mucus might easily 
be mistaken for a nucleus, but they do not stain with carmine. 
The surface of the groove, being perfectly even, shows no trace 
of such complications as are described by Claus in Aurelia, by 
von Lendenfeld in Cyanea and Crambessa, and by Hesse ('95) in 
Rhizostoma. 
