  Integrable velocity-dependent constraints are said to be semiholonomic. For
good reasons, holonomic and semiholonomic constraints are thought to be
indistinguishable in Lagrangian mechanics. This well-founded belief
notwithstanding, here we show by means of an example and a broad analysis that
the connection between symmetries and conservation laws, which holds for
holonomic systems, is not valid in general for systems subject to semiholonomic
constraints.
