276 ON THE GENUS LUCERNARIA. 
point of the natatory sac, therefore, two of these cords meet, 
run close to its border, and proceed quite to the end of the 
arms, where they become somewhat broader, and perhaps 
pass partially into the muscular system of the tentacles. 
These muscular bands are placed on the surface of the nata- 
tory sac, looking towards the cavity, and form ridge-hke 
thickenings, upon which the generative organs are developed. 
The circular muscular bands (m’) on the margin of the 
natatory sac are limited entirely to the border, where it turns 
outwards, to become continuous with the gelatinous disc. 
They extend from one arm to another, terminating at the 
summits, and perhaps giving off some fibres to the tentacles, 
the muscular system of which has been already described. 
The marginal papille arise in close contiguity with this set 
of circumferential muscles, but they receive no fibres from 
it, notwithstanding which, however, as before said, they are 
highly contractile. 
9. The generative organs.—The sexes in Lucernaria, as m 
all the Medusee,* are separate, and the generative organs are 
placed in the course of the radial canal, as in the whole family 
of the Thaumantiade. In the wall of each of the wide radial 
canals are two ridges, projecting into the cavity and running 
entirely across it. These ridges extend from the end of the 
arms, into which the margin of the bell is divided, to the 
angles of the natatory sac. Their position cannot better be 
described than by saying that they run on or near the above- 
described radial muscular bands. 
These ridge-like generative organs are very apparent, and 
both O. Fabricius as well as Lamouroux describe them as 
intestinal tubes radiating from the stomach; F. Rathke was 
the first to suggest that they were generative organs. 
More accurately considered, the generative ridges in L. 
octoradiata consist of contiguous spherical processes of the 
internal membrane of the natatory sac, within which (pro- 
bably from a growth of the outer formative membrane, as in 
the Meduse and Siphonophore) the generative products are 
developed. Whilst in the Meduse@ these processes or thick- 
enings of the walls of the radial canal project externally, in 
Incernaria they are placed on the inner aspect. The inner 
membrane, where it covers the generative organs, especially 
in the female, contains much brown pigment, and by this, 
as well as by the whitish colour of the testicular follicles 
when mature, the female can easily be distinguished from 
* As an exception to this, vd. Strethill Wright, ‘On Hermaphrodite Re- 
production in Chrysaora hyoscella,” in ‘ Aun. Nat. Hist.,’ vii (1861), p. 357. 
