Longacre's French head design combined with the "50 Cents" cereal wreath reverse. Your editor, Saul Teichman, has always questioned whether this was designed by Longacre or Paquet as the 1859 half dollar patterns used Paquet's punches in the legend "United States of America".
Examples were struck as follows:
Silver J241/P297 with over 50 believed to exist.
Copper J242/P298 with over 30 believed to exist.
Incomplete obverse splashers in white metal JA1859-2/P3212 and JA1859-3/P3215 are also known.
Photo courtesy of American Numismatic Rarities.