Outer surface of the jellyCartilaginous margin of the like disk; six of these are disk covered by thread perradial, six interradial, cells.
Primitively there are four perradial tentacles, to which may be added four interradial, or they may become very numerous and are then scattered evenly round the margin, never arranged in tufts or clusters.
66) with more than eight tentacles; Cunoctantha with eight tentacles, four perradial, four interradial.
Ra, Tentaculocysts, four perradial, four interradial.
- Surface view of the Subumbrella or oral aspect of Aurelia aurita, to show the position of the openings of the subgenital pits, GP. In the centre is the mouth, with four perradial arms corresponding to its angles (compare fig.
The transparent prolonged into the four long tissues allow the enteric cavities and oral arms, perradial in position.
Perradial, four interradial and ov, Ovaries.
Perradial and interradial canals near consist of a main stem giving off branches, and both stem and branches reach to the marginal ring-canal, the main stem ending in one of the eight tentaculocysts, which are lodged in the notches between the lobes of the umbrellar margin.
As preparations Scyphistoma of Chrysaora, with four perradial tentacles and horny basal perisarc.
For their formation the margin of the peristome of the scyphistoma grows out into eight lobes, four perradial, four interradial.
The sixteen tentacles of the scyphistoma disappear, and in the place of the four perradial and four interradial tentacles, the eight tentaculocysts of the adult are formed as outgrowths of the subumbral margin, independently of the tentacles of the scyphistoma (Friedemann).
The ephyra has a flat, disk-shaped body, with eight marginal lobes (four perradial, four interradial); a tentaculocyst is lodged in a deep notch at the apex of each lobe.
Lappet of a perradial arm.
- Medusae more or less cubical in form, with four perradial rhopalia alternating with four interradial tentacles or groups of tentacles; oral arms short; stomach a wide cavity bearing four interradial groups of phacellae and giving off four broad perradial pouches completely separated from each other by four interradial septa (i.e.
With sixteen marginal lobes, four rhopalia and twelve tentacles; the rhopalia are perradial in position, corresponding to the angles of the stomach.
Above to left, young scyphistoma with four perradial tentacles.
In some forms at least, pores between (not through) the ambulacral elements, or between them and the thecal plates, seem to have permitted the passage of extensions from the perradial water-vessels.