Above: Sketch of a probable exuva (moult) of the springtail Rhyniella praecursor, showing head with antennae (Ant), thorax (Thor) with three pairs of legs (Lg1 - Lg3), and the anterior segments of the abdomen (Abd) with the ventral tube or collophore (Col) attached to the first abdominal segment (after Scourfield 1940a & b).