We consider in space [3] a curve C of order n and genus p without multiple points. If we represent the lines of [3] by the points of a quadric Ω in [5], the chords of C will be represented by the points of a surface F of order (n−1)2−p lying on Ω. This surface has a triple curve M (with multiple points) corresponding to the ruled surface of trisecants of C (and the quadrisecants) of order ⅓(n−1)(n−2)(n−3)−p(n−2). It is the object of this note to find the genera of M and of a prime section ϑ of F; these being also the genera of the ruled surface of trisecants of C and of the ruled surface of chords of C which belong to a linear complex.