I'm having some trouble understanding the anatomical differences that classify the hippocampus as a cortical structure but not the amygdala. I have included the screenshot of a diagram from Gray's Clinical Neuroanatomy.
Medial aspect of the left cerebral hemisphere demonstrating some limbic structures (yellow). The anterior nuclear group of the thalamus is coloured orange, and the rest of the thalamus is magenta. The approximate position of the brain stem is outlined in a heavy interrupted line.