A, oraI hood (compare with Tethys, fig.
36) to the adult form has not been properly observed, and many interesting points as to the true nature of folds (whether parapodia or mantle or velum) have yet to be cleared up by a knowledge of such development in forms like Tethys, Doris, Phyllidia, &c. As in other Molluscan groups, we find even in closely-allied genera (for instance, in Aplysia and Pleurobranchidium, and other genera), the f operculum.
B, Tethys leporina, dorsal view.
1 33, 337-37 o) the son of Uranus and Gaea, the husband of Tethys, father of 3000 streams and 4000 ocean nymphs.
Between these land masses lay a great Mediterranean sea - the " Tethys " of Suess.
In the Himalaya the geological sequence, from the Ordovician to the Eocene, is almost entirely marine; there are indeed occasional breaks in the series, but during nearly the whole of this long period the Iimalayan region, or at least its northern part, must have been beneath the sea - the Central Mediterranean Sea of Neumayr or Tethys of Suess.
Its northern shores were washed by the Sea of Tethys, which, at least in Jurassic and Cretaceous times, stretched across the Old World from west to east, and in this sea were laid down the marine deposits of the Himalaya.