The operatic repertory keeps getting bigger, with most of the expansion at the two ends of the timeline. There’s been an explosion of revivals of long-ignored early Baroque and bel canto works, as well as a robust interest in brand-new pieces.

But what of the forgotten operas in the middle? The Manhattan School of Music, one of New York’s most discerning excavators of the unnoticed, has made particular efforts on behalf of rarely heard French works from early in the 20th century. (Yes, this period produced things besides the epochal “Pelléas et Mélisande.”)

In 2009, the school staged Fauré’s radiant “Pénélope” (1913). And it has just completed a brief run — quite likely the American premiere — of another opera drawn from Greek mythology: Jacques Ibert’s “Persée et Andromède,” written in 1921 and first performed in Paris eight years later.

Presented as the first half of a thoroughly delightful double bill with Ravel’s magical “L’Enfant et les Sortilèges” from the same period, “Persée” — just 40 minutes long — simply glows.

Amy Yarham, foreground left, with Yin Pei Han in “L’Enfant et les Sortilèges.” Credit Michelle V. Agins/The New York Times
It tells the story of Andromeda, chained to a rock in the sea as punishment for her mother’s boasts about her beauty. She’s overseen by a lecherous monster until Perseus comes to her rescue, which is where Ibert and his librettist (and brother-in-law), Michel Veber, throw in a twist. Sticking to the poet Jules Laforgue’s adjustment to the myth, Andromeda angrily rejects Perseus after he kills the monster. She’s despondent — until her onetime captor comes back to life as a handsome prince: “Beauty and the Beast” goes Greek.

Opening with a quivering depiction of a maritime dawn and dotted with impassioned yet lucid, classically balanced monologues for its soprano star, the lithe, autumnal score anticipates the late Strauss of “Die Liebe der Danae.” And its seriocomic spin on myth echoes that composer’s “Ariadne auf Naxos”: The close harmonies of Ibert’s six-voice chorus of nereids recalls the “Ariadne” nymphs.

James Robinson’s production gave the opera an extra, charmingly stylized ironic touch: It was set in an art museum gallery, in front of a painting depicting the Andromeda myth. The monster, Cathos (on Friday the smoky-voiced bass Hidenori Inoue), is a guard, Andromède (the limpid-tone, articulate soprano Bryn Holdsworth), a particularly starry-eyed visitor. As Persée, the tenor Taehwan Ku dealt stalwartly with a score that sends him almost immediately up to a mock-heroic high C.

Ibert was well aware of Ravel — the diaphanous, flickering start of “Persée” pays conscious homage to “Daphnis et Chloé” — so the playful yet profound “L’Enfant et les Sortilèges” made an ideal companion.

Mr. Robinson and his set designer, Allen Moyer, conjured a cartoonish but never over-the-top world, true to the piece’s intimacy and undercurrent of melancholy. As the Child, Amy Yarham, her mezzo bright and agile, led an excellent large cast. The hushed music as she entered the garden was handled with particular elegance by the orchestra, conducted in both works with an ear for transparent textures and fleet motion by Pierre Vallet.