By comparison of Raman and infrared spectra we show that longitudinal vibrational modes account for several of the peaks observed in the first order Raman spectrum of vitreous SiO2. Upon identification of the longitudinal modes, and one defect mode, transverse modes are revealed whose number and position are in good agreement with the predictions of a simple molecular model representing local forces in the perfect network. These results suggest that Coulomb forces should be included in theoretical studies of the vibrational properties of many glasses.