The medal's obverse bears first seal of the city, three diagonal crosses on shield with three vertical bars, beaver on top. Underneath, SIGILLUM AMSTELLO / DAMENSIS IN NOVO BELGIO; around edge, in two lines, ISSUED BY THE HOLLAND SOCIETY OF NEW YORK 1915 / TER HERINNERING AAN DEN 300 JAARDAG DER NEDERLANDSCHE VESTIGING OP MANHATTAS 1613

The reverse bears city seal with Native American, windmill, sailor, and beaver, crown on top. Around, COMMEMORATING THE 250 ANNIVERSARY OF THE FOUNDING OF THE BOARD OF ALDERMEN, 1665

The circular medal measures 76mm in diameter and was struck in gilt bronze. No mintage is reported.

Many thanks to Stephen Carofalo who sent me the images for this medal and also did research on all the Holland Society medals.

References:   HSoNY 1915.2