A connecting device (10; 10') for connecting an end region of an already implanted first spinal column support, in which a plurality of pedicle screws are coupled at their head side to a first connecting rod by means of a coupling device in each case, comprising an already implanted or yet to be implanted spinal column support section which has a pedicle screw and which lengthens the first spinal column support, comprising a first fastening arrangement for fastening and clamping the connecting device to the first connecting rod and a coupling for the lengthening support section, in particular in the form of a second rod to be coupled to the pedicle screw of the lengthening support section or in the form of a second fastening arrangement for fastening the connecting device to such a second rod, and further comprising a rigid bridgeover of an intermediate region between the first fastening arrangement of the connecting device and the coupling, said bridgeover laterally nestling against the coupling device of the closest pedicle screw of the already implanted first spinal column support on the connection side, wherein, for the purposes of positioning the connecting device in relation to the first spinal column support, the first fastening arrangement is, by means of a resilient device of the first fastening arrangement providing clippability, able to be attachable radially on the end region comprising the coupling device of the closest pedicle screw on the connection side, and comprising clamping means for clamping the first connecting rod to the first fastening arrangement, characterized in that the resilient device is designed in such a way that one lateral boundary of a receiving region which receives the first connecting rod and is in the form of a receiving channel formed by the inner face of a resilient arm, and the other lateral boundary is formed on the opposite side by a side structure of the first fastening arrangement which adapts the function of a fixed arm, wherein a force applied in axial direction, when a clamping screw is screwed into a threaded bore which does not extend through to the receiving region, is not centrally with respect to the middle of the first connecting rod, as seen in cross section, by off-center arrangement of the clamping screw with respect to the receiving channel. a first fastening arrangement for fastening and clamping the connecting device to the first connecting rod and a coupling for the lengthening support section, in particular in the form of a second rod to be coupled to the pedicle screw of the lengthening support section or in the form of a second fastening arrangement for fastening the connecting device to such a second rod, and further comprising a rigid bridgeover of an intermediate region between the first fastening arrangement of the connecting device and the coupling, said bridgeover laterally nestling against the coupling device of the closest pedicle screw of the already implanted first spinal column support on the connection side, wherein, for the purposes of positioning the connecting device in relation to the first spinal column support, the first fastening arrangement is, by means of a resilient device of the first fastening arrangement providing clippability, able to be attachable radially on the end region comprising the coupling device of the closest pedicle screw on the connection side, and comprising clamping means for clamping the first connecting rod to the first fastening arrangement, characterized in that the resilient device is designed in such a way that one lateral boundary of a receiving region which receives the first connecting rod and is in the form of a receiving channel formed by the inner face of a resilient arm, and the other lateral boundary is formed on the opposite side by a side structure of the first fastening arrangement which adapts the function of a fixed arm,