Homologous drop zone 1 of 2 empty. Homologous drop zone 2 of 2 empty. Analogous drop zone 1 of 2 empty. Analogous drop zone 2 of 2 empty.
a) Wing of a bat and wing of an insect
b) Dolphin flipper and wing of a bat
c) Cat foreleg and human forearm
d) Legs of a spider and legs of a dog