  We have analysed 10 high resolution spectra of Type II Cepheids with periods
less than 3 days. We find that they clearly separate into two groups: those
with near or slightly below solar metallicities, and those with [Fe/H] between
--1.5 and --2.0. While the former are usually called BL~Her stars, we suggest
that the latter be called UY~Eri stars. The UY~Eri subclass appears to be
similar to the short period variables in globular clusters of the Galactic
Halo. Globular clusters with [Fe/H] $\textgreater$ --1.0 almost never have Type
II Cepheids.
