266 ON THE GENUS LUCERNARIA. 
and afterwards, in due order, the Bell, the Stem, the Ten- 
tacles, the marginal Papille, the Stomach, the Gastro- 
vascular system, and, lastly, the Generative organs. 
1. General description—A Lucernaria (P|. XII) may be 
compared in form to a goblet or a funnel with double walls; at 
the commencement of the stem the inner wall (s) is attached 
to the outer at four points or angles, so that between these 
points four passages into the cavity between the walls origi- 
nate, the stem itself being prolonged only from the outer wall. 
At the bottom of the funnel, where the inner wall begins to 
divide at the four points, is a cylindrical elevation—the 
mouth (0) resembling the short clapper of a bell turned 
upwards, and which fills in this manner the narrow part of 
the funnel, and usually hides from view the four angles and 
passages into the inner cavity. 
In order to form a general idea of the structure, it will 
be useful here to compare the different parts of the animal 
with those of other well-known forms, and thus to abandon 
any objective description, and to include in the structural 
details some insight into the nature of the various parts. 
Sars, and Frey and Leuckart have remarked that the body 
of a Lucernaria may be compared to the disc of a Medusa. 
Four thin partition-walls (7), which spring from the before- 
mentioned points of the inner wall, divide the cavity between 
the two walls into four compartments, which communicate 
with one another round the margin of the cup (7’). The body 
of the Lucernaria so far corresponds with the disc of a Me- 
dusa, which presents four large radial vessels (which, in that 
case, may be better termed gastric pouches) and an annular 
vessel coursing round the margin. ‘These gastric pouches 
open ifto a wide aperture between the points (above men- 
tioned) of the inner wall into the cavity of the stomach, and it 
is clear that whilst the outer wall (a) of the body of a Lucer- 
naria corresponds to the gelatinous dise of the Medusa, the 
inner wall (s) represents its natatory organ. In Lucernaria, 
where the radial vessels are so disproportionately large, the 
natatory organ is connected to the gelatinous disc only in 
four narrow tracts, while in the Medusa the reverse is the 
case, and the radial vessels run between the natatory organ 
and the gelatinous disc in the form of slender channels. 
Bearing in mind that the development of the Medusze 
originates in a bud formed by the intro- and extroversions of 
two formative membranes, we shall readily perceive that 
Lucernaria represents an aborted Medusa. In the Medusa- 
bud the radial vessels are not at first separated from each 
