In a turbine for an exhaust gas turbocharger of an internal combustion engine having a housing part which has a receiving chamber and which comprises a spiral duct through which exhaust gas of the internal combustion engine can flow, the spiral duct having an outlet cross-section via which exhaust gas is directed onto a turbine wheel disposed in the receiving chamber whereby the turbine wheel can be rotated, at least one flow control member is provided which can be moved in the circumferential direction of the receiving chamber and by means of which the flow cross-section can be adjusted, wherein a warp angle of the outer contour region of the wall over which the flow cross-section can be adjusted is smaller than a wrap angle over which the outer contour region thereof extends.