What is "two-four"

Usage examples of "two-four".

Scores of lumbering Malacostracans, all bigger than Two-Four, scuttled and splashed to and fro at the poolside in what seemed like random motion.

Bass thumps from the jukebox of the bar next door, so loud it seemed as if someone was being hurled against the wall in two-four time.

Almost immediately they formed a column of fours and swung away down the great hall, their heels pounding to two-four time.

Almost imme-diately they formed a column of fours and swung away down the great hall, their heels pounding to two-four time.