The Human Cranium is composed of four vertebrae, with neural and haemal arches and appendages. The four neural arches surround the four primary subdivisions of the encephalon, namely, the cerebellum, the mesencephalon, or the nates and testes ; the cerebral hemispheres ; and the olfactory ganglia. The same succession of vertebrae is seen in the crania of other vertebrata; but in man, owing to the highly-developed and expanded state of the cerebral hemispheres, the neural arches, or rings, are separated, and the sides of the cranium require the intercalation or introduction of other bones, which, in their typical condition, do not enter into their composition. A detailed account, however, of the cranium of the lower Vertebrata, though highly useful and instructive, would exceed the limits of this work.