We show that the collective excitation spectrum of electrons with 1/r(2) interaction in a parabolic quantum dot of frequency omega(0) contains a ''breathing'' mole of frequency 2 Omega, where Omega(2) = omega(0)(2) + 1/4 omega(c)(2)and omega(c) is the cyclotron frequency, a result first obtained by Johnson and Quiroga [Phys. Rev. Lett. 74, 4277 (1995)].