  Extreme helium stars (EHe) with effective temperatures from 8000K to 13000K
are among the coolest EHe stars and overlap the hotter R CrB stars in effective
temperature. The cool EHes may represent an evolutionary link between the hot
EHes and the R CrBs. Abundance analyses of four cool EHes are presented. To
test for an evolutionary connection, the chemical compositions of cool EHes are
compared with those of hot EHes and R CrBs. Relative to Fe, the N abundance of
these stars is intermediate between those of hot EHes and R CrBs. For the R
CrBs, the metallicity M derived from the mean of Si and S appears to be more
consistent with the kinematics than that derived from Fe. When metallicity M
derived from Si and S replaces Fe, the observed N abundances of EHes and R CrBs
fall at or below the upper limit corresponding to thorough conversion of
initial C and O to N. There is an apparent difference between the composition
of R CrBs and EHes; the former having systematically higher [N/M] ratios. The
material present in the atmospheres of many R CrBs is heavily CN- and
ON-cycled. Most of the EHes have only CN-cycled material in their atmospheres.
There is an indication that the CN- and ON-cycled N in EHes was partially
converted to Ne by $\alpha$-captures. If EHes are to evolve to R CrBs, fresh C
in EHes has to be converted to N. If Ne is found to be normal in R CrBs, the
proposal that EHes evolve to R CrBs fails. The idea that R CrBs evolve to EHes
is ruled out; the N abundance in R CrBs has to be reduced to the level of EHes,
as the C/He which is observed to be uniform across EHes, has to be maintained.
Hence, the inferred [N/M], C/He, [Ne/M], and the H-abundances of these two
groups indicate that the EHes and the R CrBs may not be on the same
evolutionary path.
