The rhopalia are lodged in the notches be tween the marginal lobes of the umbrella, and each rhopalium is covered over by a little protecting flap or lappet.
In Charybdaea there are no less than six ocelli on each of the four rhopalia (fig.
Highly developed eyes, with ectodermal pigment and lens, are found also on the rhopalia of Paraphyllina (Maas [81).
- 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.
- Medusae of deep pyramidal form, often sessile, attached by a stalk developed from the centre of the exumbral surface; rhopalia absent or represented by colletocystophores.
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