12 families worldwide
6 families in North America (2 introduced).
About 35 species occur north of Mexico. (1)
Up to 200mm (tropical species)
Cylindrical body. Eyes usually present. Dorsal groove absent. Paranota absent. >30 segments. Have only one pair of legs on the fifth ring; other millipedes have two pairs. The male's sex organs (gonopods) are hidden in a pouch. (1)
Vertical suture on lower front of head extending upwards from labrum (see below) distinguishes Spirobolida from Julida and Spirostrepsida.
See also this photo