From Georges Dumezil’s The Destiny of a King (part 3 of vol. 2 of Mythe et Epopee, translated by fellow scholar Alf Hiltebeitel). Mythe et Epopee just got a reprint in Gallimard’s Quarto series and I’m discovering – which I never did when reading for research – the frequently comedic tone he adopts with some of his material. Here’s his summary of the story of Vasu Uparicara – and kudos to the translator for keeping the tone.
So it is that, through Satyavati, Vasu Uparicara turns out to be the ancestor, and a recent one at that, of the Pandavas and the Dhartarastras: excited by the thought of the twin daughter of a river and a mountain, he discharges his semen, which is swallowed by a nymph-turned-fish; and the fully human daughter, a twin again, who is drawn from the latter’s stomach, gives birth, in two successive states of virginity, to the real grandfather, and then to the putative grandfather, of the two groups of cousins.