Erratum
The negative for figure 4 in the article "Molecular models for DNA damaged by photoreaction" by D. A. Pearlman et al. (15 Mar., p. 1304) was accidentally reversed when prints were being made, resulting in a Picture that is the mirror image of the correct one. The error does not affect any of the conclusions made in the article. A corrected version of this figure may be obtained upon request from the authors.