  M-theory compactification on a manifold X of $G_2$ holonomy can give chiral
fermions in four dimensions only if X is singular. A number of examples of
conical singularities that give chiral fermions are known; the present paper is
devoted to describing some additional examples. In some of them, the physics
can be determined but the metric is not known explicitly, while in others the
metric can be described explicitly but the physics is more challenging to
understand.
