This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Origin of Vertebrates Fig . Fig Horizontal Section through the Brain of Ammoctes Cr membranous cranium olfactory nerves lateral ventricles gl glandular tissue which fills up the cranial cavity All references in this work to Ammoctes or Petromyzon appear to refer to the species now called Lampetra planeri The Origin of Vertebrates