Srimad Bhagavatam Canto 06, Chapter 18, Text 05

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.
Srimad Bhagavatam Canto 06, Chapter 18, Text 03-04
Srimad Bhagavatam Canto 06, Chapter 18, Text 06