This is Morgan's eagle design identical to the one made the prior year J1545/P1718 except for the date.
This design was also made into a half eagle J1577-J1578/P1770-P1771.
2 examples are known in gold J1581/P1774 including the Massamore 11/1884, Steigerwalt 4/1885, Scott 11/1888 (Foster Ely), C.F. Libbie 10/01, Mitchelson, Connecticut State Library example and the other the ex Parmelee, Chapman Brothers, Brand, Judd, Wilkison, southern collection, Simpson-Heritage 8/21 - NGC66/PCGS66.
Only 3 examples are known in copper J1582/P1775 including 2 in the Smithsonian and the illustrated example ex Newcomer?, New Netherlands 6/59 lot 1748?, Bowers and Merena's 3/2000, Heritage 5/01, Heritage 1/07 as PCGS62RB, Simpson-Heritage 4/21 - PCGS63RB.
It was cleaned at one time.
Additional information on these can be found in the article "The 1884 Connection: A History of the 1878 U.S. Gold Patterns" in the November 1981 issue of The Numismatist.
A reverse hub trial showing just the eagle, struck in lead, JA1878-5/P3464 is also known.
Photo courtesy of PCGS.