This conclusion has shown that the Euthyneura do not represent an archaic form of Gastropoda, but are themselves derived from streptoneurous forms. The difference between the two sub-classes has been shown to be slight; certain of the more archaic Tectibranchia (Actaeon) and Pulmonata (Chilina) still have the visceral commissure long and not untwisted.
In Actaeon and Limacina among Opisthobranchia, and Chilina among Pulmonata.
Actaeon is prosobranchiate, the visceral commissure is twisted in Actaeon and Chilina, and even slightly still in Bulla and Scaphander; in Actaeon and Limacina the osphradium is to the left, innervated by the supra-intestinal ganglion.
Actaeon, Limacina, and the marine Pulmonate, Amphibola.
The genital duct is now said to be diaulic, as in Valvata, Oncidiopsis, Actaeon, and Lobiger among the Bullomorpha, in the Pleurobranchidae, in the Nudibranchia, except the Doridomorpha and most of the Elysiomorpha, and in the Pulmonata.
It is one of the more typical Opisthobranchs, that is to say, it belongs to the section Tectibranchia, but other members of the suborder, namely, Bulla and Actaeon (figs.
44 and 45), are less abnormal than Aplysia in regard to their shells and the form of the visceral hump. They have naked spirally twisted shells which may be concealed from view in the living animal by the expansion and reflection of the parapodia, but are not enclosed by the mantle, whilst Actaeon is remarkable for possessing an operculum like that of so many Streptoneura.
D, E, Dorsal and lateral view of Elysia (Actaeon) viridis.
Hermaphrodite genital aperture, connected with the penis by a ciliated groove, except in Actaeon, Lobiger and Cavolinia longirostris, in which the spermiduct is a closed tube.
Some of the titles of his plays, Danaides, Actaeon, Alcestis, Tantalus, show that he treated mythological as well as contemporary subjects.
ACTAEON, son of Aristaeus and Autonoe, a famous Theban hero and hunter, trained by the centaur Cheiron.
Another tradition represents Actaeon as the lover of Semele, and his death as due to the jealousy of Artemis.