From Poetry Wiki
A dactyl (Gr. δάκτυλος dáktulos, “finger”) is a type of meter in poetry. In quantitative verse, such as Greek or Latin, a dactyl is a long syllable followed by two short syllables, as determined by syllable weight. In accentual verse, such as English, it is a stressed syllable followed by two unstressed syllables -- the opposite, that is, of the anapaest (two unstressed followed by a stressed syllable).
The word "poetry" is itself a dactyl, as pointed out in the New York Times Crossword Puzzle (Will Shortz, ed.) for May 31, 2006. A useful mnemonic for remembering this long-short-short pattern is to consider the relative lengths of the three bones of a human finger: beginning at the knuckle, it is one long bone followed by two shorter ones.
- This is the / forest prim- / eval. The / murmuring / pines and the / hemlocks,
The first five feet of the line are dactyls; the sixth a trochee.
- Picture your self in a boat on a river with
- tangerine tree-ees and marmalade skii-ii-es.
Written in dactylic tetrameter, the verses of the song have the rhythm of a waltz. The word "skies" takes up a full three beats. Dactyls are the metrical foot of Greek elegiac poetry, which followed a line of dactylic hexameter with dactylic pentameter.