170 BULLETIN OF THE 
in the young of Cyanea. In Aurelia, Plate VII. fig. 6, they are represented by 
wart-like excrescences of small size, covering the whole upper surface of the 
bell, even to the marginal lobules. 
ON THE SENSE ORGANS FOUND ON THE BELL MARGIN OF 
CYANEA ARCTICA, 
The structure of the sense organs found in the rim of the bell of Pelagía, 
Aurelia, and Cyanea has been carefully studied by Dr. Eimer. His observations 
of Oyanea axe less complete than of the other genera, and as the differences are 
in some respects so radical, 1 have here described the more important details 
of their anatomy again. The “marginal sense bodies ” of C. arctica are eight in 
number, and are situated at equal distances on the rim of the umbrella in in- 
cised angles, slightly removed from the margin. Morphologically, each of these 
structures is a modified tentacle, as pointed out by Agassiz. 
The eight extensions of the stomach in the interval between the lower sur- 
face of the umbrella and the lower floor are separated from each other by verti- 
cal partitions connecting these structures. "The early condition of these vertical 
partitions has been already mentioned in speaking of the ephyra. It remains 
to be noticed that they lie in radial lines, separating the octants which bear the 
sense bulb from those from which the bundles of marginal tentacles hang. 
The chymiferous tubes or extensions from. the stomach into the periphery of 
the disk divide as they approach the margin of the umbrella into a single small 
central, and two large lateral branches. The central of these, which is medially 
placed, extends directly into the otocyst, while the lateral divisions are subdivid ed 
into many dendritic branches, becoming more and more subdivided as they ap- 
proach the margin of the lobes on either side of the sense bulb or otoeyst. It 
will be seen, however, by a consultation of the figures, Plate VII. figs. 7, 12, 
that only a part of the lobes adjacent to the sense bulb is penetrated by branches 
from the optical extension of the stomach, part of which passes into the otocyst. 
By far the greater number of dendritic branches arise from chymiferous 
tubes, which lie in the same sector as the bunch of marginal tentacles. The 
dendritic branches of the main divisions of the ocular tube are of two kinds, 
one of which spreads itself out in the margin of the umbrella, while the other, 
arising from the sides of these tubes, extends into curtain-like folds (Plate VII. 
fig. 12 c) on the under surface of the umbrella. These curtains are placed as fol- 
lows. On the aboral side of the adult Cyanea the otocyst is covered and pro- 
tected by a roof-like prolengation of the upper surface of the umbrella into 
what is known as the hood (Plate VIT. fig. 12*, d). On the oral side, this hood 
does not exist in the same form. It is, however, represented in the oral cur- 
tains. When one carefully examines the otocysts from below, or from the oral 
side, they are found to be protected by raised walls or curtains, which do not 
join each other, but arise from the edges of the adjacent lobes and extend par- 
allel with each other from the base of the otocyst to a distance far beyond 
its distal end. They are so placed in reference to each other that their free 
edges, which are crescent-shaped, slightly overlap (Plate VII. fig. 12, c). It 
