An illustration shows vertebrate brains of bony fish, amphibian, reptile, bird, and mammal. The parts of brain are color coded as pink for Olfactory Bulb, blue for Cerebellum, olive for Cerebrum, yellow for Medulla Oblongata, light purple for Optic Lobe, and green for Spinal Chord. The cerebrum and cerebellum increase in size from fishes to mammals.