(Here's a more elaborate version -- in title as well as detail -- of the costume for "Dusk" from the same manual. Note that if you're "in the gloaming", you get to have a bat and an owl!)
GLOAMING, IN THE. Dress of grey tulle, or muslin, or gauze over satin, made as an ordinary evening dress, or in classic fashion; a veil of the same material; fire-flies imprisoned in the tulle; bat fastened on one shoulder, an owl on the other; silver and smoked pearl ornaments.
The above is from the 1887 edition of Holt. "Dusk" is upgraded after this -- in 1896, that entry, which "In the Gloaming" refers the reader to, uses exactly the description as given above.
Sources:
Holt, Ardern. Fancy Dresses Described, 5th Edition. London: Debenham & Freebody, 1887.
Holt, Ardern. Fancy Dresses Described, Sixth Edition. London: Debenham & Freebody, 1896.
The 1896 edition of Holt may be found online at the University of Wisconsin Digital Collections.