Before revision: In those Springtails (Collembola) that have a functional furcula, the underside of the third abdominal segment bears a hooked structure, variously called the retinaculum or hamula.
After revision: In those springtails (Collembola) that have a functional furcula, the underside of the third abdominal segment bears a hooked structure, variously called the retinaculum or hamula.