  Stellar spectral classification has been highly useful in the study of stars.
While there is a currently accepted spectral classification system for carbon
stars, the subset of Hydrogen-deficient Carbon (HdC) stars has not been well
described by such a system, due predominantly to their rarity and their
variability. Here we present the first system for the classification of HdCs
based on their spectra, which is made wholly on their observable appearance. We
use a combination of dimensionality reduction and clustering algorithms with
human classification to create such a system with eight total classes
corresponding to temperature, and an additional second axis corresponding to
the carbon molecular band strength. We classify over half of the known sample
of HdC stars using this, and roughly calibrate the temperatures of each class
using their colors. Additionally, we express trends in the occurrence of
certain spectral peculiarities such as the presence of Hydrogen and Lithium
lines. We also present three previously unpublished spectra, report the
discovery of two new Galactic dustless HdC (dLHdC) stars and additionally
discuss one especially unique star that appears to border between the hottest
HdCs and the coolest Extreme Helium (EHe) stars.
