Reference for Bekhorot 84:11

ולימא רבי יוחנן נמי

who gave a decision that a tumtum animal which urinates in the female part is hullin<span class="x" onmousemove="('comment',' An unconsecrated animal. It is considered a sure female, as we entertain no fears about the sex being changed, and the law of the firstling does not apply to a female.');">⁶</span>

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