  We report on HST/WFPC2 U,V and far-ultraviolet observations of two Galactic
Globular Clusters (GGCs), NGC 6205 = M13 and NGC 6093 = M80. Both of these
clusters have horizontal-branch (HB) tails that extend to the helium-burning
main sequence, with the hottest stars reaching theoretical effective
temperatures above 35,000 K. In both clusters, groups of stars are found to be
separated by narrow gaps along the blue HB sequence. These gaps appear at
similar locations in the color-magnitude diagrams of the two clusters. While
stochastic effects may give rise to variations in the color distribution along
the HB, the coincidence of gaps in different clusters effectively rules this
out as the primary cause. The comparison among the clusters strongly suggests
that there are separate physical processes operating during the earlier
red-giant phase of evolution to produce mass loss.
