SB 6.18.5
valmikis ca maha-yogi
valmikad abhavat kila
agastyas ca vasisthas ca
mitra-varunayor rsi
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
By the semen of Varuna, the great mystic Valmiki took birth from an anthill. Bhrgu and Valmiki were specific sons of Varuna, whereas Agastya and Vasistha Rsis were the common sons of Varuna and Mitra, the tenth son of Aditi.