A lesson on homologous structures today. Uncle Darwin defines them as anatomical parts that share similar structures. I sketched a few examples so I'll remember and impress the other girls at Miss Emily's when I got back:
From Left to Right: Scalopus aquaticus (Mole), Equus ferus (Horse), Desmodus rotundus (Common Vampire Bat). They all seem to share the same common ancestor, no?