Do Quasars Lens Quasars?

If the unexpectedly high frequency of quasar pairs with very differentcomponent redshifts is due to the lensing of a population of background quasarsby the foreground quasar, typical lens masses must be $\sim10^{12}M_{\sun}$ andthe sum of all such quasar lenses would have to contain $\sim0.005$ times theclosure density of the Universe. It then seems plausible that a very highfraction of all $\sim10^{12} M_{\sun}$ gravitational lenses with redshifts$z\sim1$ contain quasars. Here I propose that these systems have evolved toform the present population of massive galaxies with M$_{\rm B}\leq-22$ and $M>5\times10^{11} M_{\sun}$.Comment: 6 pages, aas style, ams symbols, ApJL (accepted