Stephen mocks himself in Proteus for praying "to
the devil in Serpentine avenue that the fubsy widow in front
might lift her clothes still more from the wet street."
A "fubsy" person is chubby and squat.
But the widow aroused Stephen in some way that he is still
seriously thinking about. In Circe he weaves the
memory into his prophetic dream of Haroun al Raschid: "It
was here. Street of harlots. In Serpentine avenue Beelzebub
showed me her, a fubsy widow. Where's the red carpet spread?"
Stephen (or whatever hallucinatory version of his
consciousness the episode is presenting us with) seems to be
expecting to meet his widow in the red-light district,
fulfilling the promise of the man in the dream (recalled in Proteus)
to introduce him to someone important: "In. Come. Red carpet
spread. You will see who."