We address a discrepancy between the large singlet-triplet (S-T) splitting values computed by advanced ab initio methods for three of the dihalocarbenes CX2 (X = Cl, Br, I) and the much smaller values deduced from khotoelectron spectra of CX2-. ions. Our G3 calculations lead us to propose that the band of CX2-. (X = Cl, Br, I) that is presently attributed to the (2)[X-C -X](-.) --> X-3-C-X transition is actually due to photodetachment from a metastable species, (4)[X-C-X](-.) --> X-3-C-X or, less likely, (4)[C=X-X](-.) --> (3)[C=X-X] (and, conceivably, (2)[C=X-X](-.) --> (3)[C=X-X]).