A miscegen is a hybrid, particularly of white and black.

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1864.  Miscegenation occurs as the title of a pamphlet. (N.E.D.)

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1864.  A very sprightly suffragan of a miscegen stamp…. The result would be an average miscegen and a superior patriot.—S. S. Cox, ‘Eight Years in Congress,’ p. 354 (1865).

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1864.  [Do they] rely upon the new system, called by the transcendental abolitionists “Miscegenation,” to save the black?—Id., p. 357.
  [See the whole speech, pp. 352–70.]

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