supernumerary

This method applies to the observation of angles, usually obtained by repetitions; and instead of equating directions, as in the first method, its object is to furnish the most probable values for the several observed angles from a supernumerary number of angles.

a supernumerary nipple; a supernumerary tooth

Resolved, that the Curators be authorized to exchange with other societies or individuals, such duplicate or supernumerary specimens of coins, medals, minerals and other articles as they may deem unnecessary to be retained in the Cabinet of the Society, for such other specimens, of equal value, as they may consider desirable to be added to the Society's present collection; […]