"O Wondrous Type! O Vision Fair"

Last year, I noticed a small feature in the Transfiguration hymn "O Wondrous Type! O Vision Fair."  It's sung to the tune "Deo gracias."  Here's the third musical phrase:

In the fourth verse, the text here is "For which in joyful strains we raise" (the sense is continued into the next line:  "The voice of prayer, the hymn of praise").  "Joyful" is sung with a melisma (C Bb Ab), providing a sense of either ebullience or abundance (for the "-ful" suffix).