HISTORICAL SKETCH In 1889 a woman who presented a group of symptoms hitherto underscribed entered Dr. P. G. Unna's clinic for skin diseases in Hamburg. The case was referred to me for description and publication, and the report appeared in theInternational Atlas for Rare Skin Diseasesin 1891 under the title of "Acanthosis Nigricans." Before the publication of my paper a similar case was observed by Janovsky of Prague, who sent the description of his case to theInternational Atlas, and the two cases appeared in the same issue, Janovsky accepting for the disease the name which had been proposed by Unna. On the occasion of my visit to Paris in the summer of 1890, Darier showed me two cases of the same disease which had shortly before come under observation at the Hospital St. Louis, and which