its second end 26b fixed to a cross member 28 which interconnects the arms 26 and is parallel to the articulation axis x x the oscillation of the assembly 25 about the axis x x is driven in synchronism with the machine by means of a pair of connecting rods 29 as will become clear from the description of the operation of the machine a suction manifold 30 is connected to the cross member 28 of the oscillating assembly 25 and is connected at 30a by means of a connecting tube 49 to the inlet of a suction fan 31 the manifold 30 has a lower edge portion 30b defining a first jaw of a pincer device the manifold 30 also has a wall 30c which faces the supply unit 12 and has a curved shape in order to prevent interference with the movement of other members of the machine a lower jaw 32 is pivoted to the manifold 30 about a horizontal axis y y parallel to the articulation axis x x of the oscillating assembly and has an active portion 32b facing the portion 30b of the manifold 30 the second jaw 32 is moved by means of a pair of connecting rods 33 each pivoted at a first end to the jaw 32 about a horizontal axis parallel to the axis y y and at a second end to one of a pair of levers 34 keyed to.