Corinphila (Zurich) auction 96 (March, 1997), lot 81.  Estimate 75,000 Swiss Francs; realized 170,000 Swiss Francs.  Switzerland · Canton Basel. "Basel Dove" 2 1/2 Rappen in a vertical pair with the "Hood on Dove" plate error in the lower stamp:  on piece with postmark "BASEL 3 AOUT VOR-MITTAG".  The only known pair with the "before noon" postmark.
<a href="https://de.wikipedia.org/wiki/Melchior_Berri" class="extiw" title="de:Melchior Berri">de:Melchior Berri</a> (1801 - 1854)
The original description page was <a class="external text" href="https://en.wikipedia.org/w/index.php?title=File:Basel_Dove%2C_pair_showing_hood_variety.gif">here</a>. All following user names refer to en.wikipedia.