ταύτης

From LSJ

Δελφῖνα νήχεσθαι διδάσκεις: ἐπὶ τῶν ἐν ἐκείνοις τινὰ παιδοτριβούντων, ἐν οἷς ἤσκηται → Teaching dolphins to swim: is applied to those who are teaching something among people who are already well versed in it

Source

French (Bailly abrégé)

gén. fém. de οὗτος.

Russian (Dvoretsky)

ταύτης: gen. f к οὗτος.