SIMPLICIA. 
651 
ating in the stomach, and proceedings by ramifications toward the circumference. Another species, C. chrysaora, 
has the margin furnished with long tentacula, and rows of brown or yellow spots, forming rays on the convex 
surface. It is very common, and there are great varieties in the spots. 
Cuvier distinguishes under the name of 
Rhizostoma, — 
Those Medusae which have no central opening or mouth, and which are thence supposed to draw their 
nourishment by suction by the ramifications of the peduncle, or by the tentacula. They have four 
ovaries or more. 
Rhizostoma, properly so called, have a central peduncle, more or less ramified according to the species. The 
vessels which, arise in the small pi-otuberances of the peduncle, unite in a cavity at its base ; and from this, other 
vessels are ramified to all parts of the umbrella, or disc. The most common species is the blue Rhizostoma, which 
is often left on sandy shores by the ebbing tide. The umbrella is sometimes two feet in diameter. The peduncle 
is composed of four pairs of arms, which are very much branched and toothed, and each is furnished with two 
auricles or appendages at the base, which are also toothed. A fine network of vessels, occupying the thickness of 
the margin, extends all round the umbrella. According to the observations of MM. Audouin and Milne Edwards, 
these MeduscE are social, or at least they are always met with in numerous shoals, swimming in the same direction, 
and with the body obliquely inclined. 
The Cephece of Peron differ from the other Rhizostoma only by having filaments intromixed with the denta- 
tions, or papillae of the peduncle. The Cassiopei<e have no peduncle ; and their arms, which are usually eight in 
number, and sometimes branched, rise directly from the under surface. 
Astoma, — 
Might be the general name for those which have no central mouth, no ramifications of the peduncle, 
and no cavities for the ovaries. 
Some, however, have the peduncle furnished on each side with filaments that may act as suckers. Others have 
no filaments, but the extremity of the peduncle is hollowed out like a funnel, which seems to be the sucker, as 
from it vessels ascend the peduncle, and others are ramified from its base all over the body. Others again, want 
the funnel-shaped membrane, or it may have been mutilated before the specimens were obtained. There are still 
others, which have no vestige of a peduncle ; but merely little suckers distributed over the under surface, on the 
lines of the vessels which are ramified below it ; [and these suckers are, of course, so many little mouths]. Some 
have no vestiges of suckers or any other external apparatus, but have both sides smooth ; and there are yet others 
which have no trace even of internal vessels. The under surface of these is usually concave, and may act as a 
stomach. These last are very simple animals, and differ from Hydra in scarcely anything but size. 
Beroe. 
This genus should be separated entirely from the Medusae. It has a globular body, provided with 
salient ribs, extending from the centre of the upper surface to that of the under, and bristled with 
points or filaments, which appear to be connected with vessels in which there is some appearance of a 
fluid circulating. The mouth is on the one extremity, and leads to a stomach, which occupies the axis 
of the body. There are also on the sides two organs, which are probably analogous to what are con- 
sidered the ovaries of the Medusae. 
B. pileus, a species very common in the Channel, has the body spherical, with eight ribs, and two ciliated 
tentacula, which become very long byprejection of their inferior extremities. MM. Audouin and Milne Edwards 
have described its natural organization with considerable minuteness, and have traced various sets of vessels, 
but without being able very clearly to explain their functions. This species is understood to constitute great part 
of the food of the common Whale. Naturalists have referred to the same genus very simple species, which consist 
of only a sac, furnished with ciliae, and open at both ends. The Doliolam of Otto have not even projecting ribs, 
but resemble barrels without bottoms. 
Callianir<B of Peron, differ fi’om Beroe only in having the ribs more salient, and united two and two, so as to 
form two sets of a sort of wings. Janira, resemble the last; but they have upon each side three long ciliated 
ribs, and two filaments. Alcinacce, have a cylindrical body, open at the one end, and two large wings at the other, 
which when folded up completely cover the body. The cylindrical part is marked with four salient ribs, which 
end in points, and have eight braces of ciliae. Ocyracee, have similar wings ; but they have no ribs, and only 
four rows of ciliae on the cylindrical portion. 
Cestum, — 
Bears, perhaps, the nearest resemblance to Beroe than to any other genus. It is a very long gelatinous 
i ribbon, having one of the sides furnished with two rows of ciliae, and there are fainter traces of the same 
on the other side: the mouth is in the middle of the inferior edge, and the stomach is embodied in the 
gelatinous substance of the ribbon ; from the anal extremity there proceed vessels which ramify toward 
j both extremities of the ribbon ; and near the sides of the mouth there are two vessels which are pro- 
