16 families worldwide.
9 families in North America (8 native, 1 introduced).
Long, snake-like body. Eyes present. Often with fringe of setae around posterior end of body. Dorsal groove absent. Paranota absent. 1st pair of legs hook-like in males. 30-90 segments. Conspicuous grooves ("striae") on the segments in families Julidae and Paeromopodidae.