Listening to the sound his feet are making ("Crush, crack, crick, crick"), the poet in Stephen recalls a familiar fragment of verse and thinks, "Rhythm begins, you see. I hear. A catalectic tetrameter of iambs marching." Derived from a Greek word meaning "incomplete," a catalectic line of verse is one missing a syllable from the expected structure, in this case iambic tetrameter (dee DUM dee DUM dee DUM dee DUM).

JH 2013

Scansion of Stephen's lines using slashes for stressed syllables and lower-case x for unstressed, and two added syllables that could make the first line either catalectic iambic tetrameter or catalectic trochaic tetrameter. Source: John Hunt.

Timothy Steele's scansion of a poem by John Keats, using the same marks for stressed and unstressed syllables and carets for syllables omitted in catalectic lines. Source: