A device for connecting and locking structural panels, particularly floor panels, having a groove forming an upper lip and a lower lip over the entire length of at least one lateral border and with a tongue formed on the opposite lateral border corresponding to the groove. To lock panels that have been connected, the tongue is provided with at least one projection and the groove exhibits at least one indentation on the lip that faces the projection, which device is characterized by the indentation being longer than the projection, and on its lateral border (I3, I4) the lip provided with at least one indentation exhibits at least one recess reaching back to the indentation. The length of the recess is at least as great as the length of the projection, and seen in the longitudinal direction, the recess and the projection occupy positions that are staggered, one relative to the other.