Reference for Ketubot 151:4

הכא במאי עסקינן ביתירת יתירת מאי ראיה מייתי ראיה דראה וניפייס הוא:

What are we dealing with here? With the case of a woman who had a superfluous limb. [But if] she had a superfluous limb what proof could be brought? Proof that the man has seen it and was reconciled to it.

Jastrow