  Let $G$ be a cubic graph which has a decomposition into a spanning tree $T$
and a $2$-regular subgraph $C$, i.e. $E(T) \cup E(C) = E(G)$ and $E(T) \cap
E(C) = \emptyset$. We provide an answer to the following question: which
lengths can the cycles of $C$ have if $G$ is a snark? Note that $T$ is a hist
(i.e. a spanning tree without a vertex of degree two) and that every cubic
graph with a hist has the above decomposition.
