In January, 1921, while delivering a clinical lecture before the Douglas County Medical Society, at Lawrence, Kansas, I encountered a case of nail disorder which was entirely new to me. REPORT OF CASES Case 1.— The patient was a young woman, under the care of my friend, Dr. H. L. Chambers, and the affection, which involved the nail of the left thumb, had been present for about one year. There was no history of injury, and, in so far as could be demonstrated, the patient was free from syphilis and tuberculosis. The earliest noticeable manifestation was a small, hard, rounded, painless tumor at the base of the nail. The growth had increased gradually in size until it was about 0.5 cm. in height, and 0.7 cm. in width. Coincident with its development, a V-shaped groove had appeared in the nail, extending from the matrix to the free margin, and gradually