Skulls of different pigeon breeds
Adolf Bernhard Meyer (1840-1911)
Adolf Bernhard Meyer (1840-1911): <a rel="nofollow" class="external text" href="https://archive.org/details/AbbildungenvonV1Meye">Abbildungen von Vogel-Skeletten</a> (1879) <a rel="nofollow" class="external text" href="https://archive.org/stream/AbbildungenvonV1Meye#page/XXXI/mode/1up">XXXI</a>