  Analysis of HST STIS ultraviolet spectra of two hot extreme helium stars
(EHes): V1920 Cyg and HD 124448 provide the first measurements of abundances of
neutron-capture elements for EHes. Although the two stars have similar
abundances for elements up through the iron-group, they differ strikingly in
their abundances of heavier elements: V1920 Cyg is enriched by a factor of 30
in light neutron-capture elements (Y/Fe, Zr/Fe) relative to HD 124448. These
differences in abundances of neutron-capture elements among EHes mirrors that
exhibited by the RCrB stars, and is evidence supporting the view that there is
an evolutionary connection between these two groups of hydrogen-deficient
stars. Also, the abundances of Y and Zr in V1920 Cyg provide evidence that at
least one EHe star went through a s-process synthesis episode in its earlier
evolution.
