A.Gill clefts in the vertebrate embryos
B.Wings in the insects, birds and bats
C.Jointed legs of arthropods and mammals
D.Excretory organs in earthworm and frog
A.Gill clefts in the vertebrate embryos
B.Wings in the insects, birds and bats
C.Jointed legs of arthropods and mammals
D.Excretory organs in earthworm and frog