In Amphibians and Other Anamniotes
In amphibians, the telencephalon distinctly shows medial, dorsal, lateral and ventral parts of the pallium, plus striatal, pallidal, diagonal and preoptic parts of the basal nuclei. However, the pallial portions do not show a visible lamination. They already have a mixture of glutamatergic (excitatory) and GABAergic (inhibitory) neurons, whereas the subpallium is largely populated by inhibitory neurons. This structure is very similar to that found generally in anamniotes, though cartilaginous fishes do show a layered arrangement of their pallial neurons.
Read more about this topic: Pallium (neuroanatomy)