The two cases which are incorporated in this report, and about which revolves the discussion of the subject of nonparasitic cysts of the leptomeninges of the spinal cord, are found to be quite uncommon, even though a most thorough search of the literature is made. The bulk of the reported arachnoidean cysts have for their etiology either the cysticercus or echinococcus, which means that they are multiple and complicated. Moreover, it is highly important that the simple, nonparasitic cysts like those which I am placing on record be recognized early, so that immediate proper operative intervention may be instituted. Then a fair prognosis may be offered. A plea for an early recognition of the nature of the trouble is a chief motive for placing before the profession a report of my two interesting and instructive cases. The first patient was in an extreme paraplegic state when first observed. Operative treatment