Millipedes have bodies divided into many segments, with each segment having 2 pairs of legs. The seventh segment (from the front) of males have modified legs (gonopods) used for reproduction. If you find a millipede which seems to have legs missing from the seventh segment, it is a male.
When on the move, a Narceus millipede moves rapidly over most surfaces. This is in contrast to the flat-bodied millipedes such as the much slower-moving Sigmoria which is also present in eastern Ontario. If you wish to see a millipede in action, view this short movie clip (approx. 15 seconds, 640 KB, requires QuickTime to view).
Pairs of millipedes are occasionally found mating (see above). During my hikes, most pairs that I have encountered have been found in late summer or early autumn.
This close-up of a mating pair provides a good view of the antennae, and the ocelli of the millipede's compound eyes. Also, the spiracles (holes in the skin for respiration), are visible as a row of dots along the body segments.
Occasionally, I come across the exoskeleton of a millipede. Most are probably the shed exuviae of growing millipedes, but sometimes they may be the remnants of one that has died.