274 R. T. GUNTHER. 
mesogloea being slightly turned up, forming a sort of “ burr” 
on the side of the ectoderm. | 
The sense-organ consists of an almost spherical sense-bulb 
and a containing capsule. The sense-bulb is composed of a 
number of clear, refringent nucleated cells, sometimes arranged 
in two layers, as in fig. 2, B, where several large central cells 
(four are seen in the figure) are surrounded by numerous 
flattened cells, but more often the central and sheathing cells 
are so mixed up that it is impossible to distinguish between 
them. At the base of the sense-bulb there are generally a few 
very granular cells, by which the bulb is attached to one wall 
of the capsule. The capsule is buried in the nettle-ring and 
lined by an endothelium of very thin pavement-cells. 
In the young sense-organ the bulb consists of a number of 
squarish peripheral cells, all grouped round one or more large 
axial granular cells (figs. 1 and 2, 4.). In the young organ 
there is not so much space between the wall of the capsule and 
the bulb as in the fully-grown organ. The endodermal axis of 
the fully-grown organ is completely shut off from the endoderm 
of the circular canal, from which it has sprung, by a thick 
plate of mesogloea. 
Generative Organs.—As is the case with the Ocellata, 
the genital organsare developed from the ectoderm of the manu- 
brium, In sexually mature animals the ectoderm of the 
proximal two thirds of this organ is very much thickened 
owing to the prolific growth of the sexual elements in this 
region. Inside the area occupied by the genital organs the 
endodermal lining of the csophagus is modified (figs. 3 
and 4, end.). It is much thickened, and consists of 
long cells, the outer ends of which are probably flagellated, 
though the flagella were not preserved in the material exa- 
mined. The protoplasm contains numerous granules of foreign 
matter, and, as in similar cases described by Hertwig (7), 
“has a plant cell-like appearance.” The mesoglea becomes 
unusually thin in the region of the sexual organs, though 
tolerably thick on either side of that region. Thus far, the 
structure of the manubrium in the region of the genital organs 
