Nerve impulses are conducted more rapidly in myelinated fibres than in non-myelinated fibres.

Explanation

The presence of a myelin sheath in myelinated fibres increases the velocity of conduction and also reduces the energy expended in the process of conduction. In myelinated fibres, the conduction takes place by jumping of the action potential from one node of Ranvier to another, instead of travelling along the nerve membrane as in a non-myelinated fibre.