I have now dealt at some length with atypical and unusual conformations of brain-surface relevantly to mental standing, by description both of the general and of the local deviations from more usual arrangement; and have described aberrant brain-forms—abnormal defects or aberrations of cerebral gyres and furrows—which may serve as a stigma of degeneracy in the stock from which the individual springs; or may arise from disturbances in the very foundations of being, due to pathological and developmental anomaly during intra-uterine or during early extra-uterine life. In the course of the preceding chapters it has been necessary to discuss so many matters, and with so much detail, concerning the brain-surface morphology, that it will now be useful to resume, on lines both broad and brief, some of the principal features of interest and importance.