Nigon is the second underground race.

Hmm... I highly doubt that a hydra has six brains, one in each head. After all, it's not 6 snake-siamese twins (well, that's quite a stretch :D), it has one brain. Maybe its brain isn't located in its head at all, like it was with the stegosaurus, or rather, it had a "posterior" brain in the pelvic area, which controlled many reflexes... Anyway, if you're interested, read Wikipedia at this link:
http://ru.wikipedia.org/wiki/%D0%A1%D1%82%D0%B5%D0%B3%D0%BE%D0%B7%D0%B0%D0%B2%D1%80
But I think my point is clear. And ogres are something like siamese twins or some kind of mutants, so they have 2 brains and 2 minds.