Special thanks to John Campbell for this image. This bronze medallion may be a participation or finishers medal from the 1891 PBP race. The latin motto "Robur et Celeritas" means "strength and speed". You will notice that there is no direct reference to Paris Brest on the medal. The delcampe.net web site claims on one page that this is a Paris Brest et Retour medal, but in the two other versions of the medal I found when searching on the motto there is no reference to Paris Brest. The other 1891 medal in this section is far more likely to be the offical medal, but this one remains a curiosity.

Enlarge Front - Enlarge Back

Explanation on delcampe.net
(screen capture - jpg)