The egg-producing ovaries reside in segment 13, from which eggs are released through the female pores into egg sacs in segment 14. The clitellum of one worm lies opposite segments 9-11 of the other, which, you'll remember, contain the male parts. The worms now secrete tremendous amounts of mucus , until each is enclosed in a slime tube extending from segment 9 to the rear end of the clitellum at segment 37. Now sperm are ejaculated from segment 15 and carried backward in tubes formed by grooves in the body touching the slime tube and the sperm pass to the sperm receptacles on segments 9 and 10 of the other worm. Then the earthworms go their different ways.
Sex is done.
However, that is not to say that eggs have been fertilized, because they haven't. It's just that now, in each worm's sperm receptacles, there are sperm from the other worm. The next step in producing baby earthworms comes when the earthworm is by itself. Its clitellum secretes a second mucous ring that slides forward over the worm's body. When the ring passes the openings in segment 14, several ripe eggs leave the body and stick to the ring.