Yuma Round-tailed Ground Squirrel (at left), Mohave Ground Squirrel (at right)
<bdi><a href="https://en.wikipedia.org/wiki/en:Louis_Agassiz_Fuertes" class="extiw" title="w:en:Louis Agassiz Fuertes"><span title="United States ornithological artist (1874-1927)">Louis Agassiz Fuertes</span></a>
</bdi>
Joseph Grinnell and Joseph Dixon <i>Natural History of the Ground Squirrels of California</i> 1918