The literature of "chronic progressive chorea," according to Good,1 dates back to 1842, when Dr. C. O. Waters of Franklin, New York, described in a letter to Dr. Dunglison a peculiar form of chorea, which he said was markedly hereditary, rarely appeared before adult life, was incurable, and always induced dementia. The common people called this disease the "megrims."Dr. George Huntington,2 in an article on chorea published in 1872, gave the first good description of the disease which now bears his name; he called it "the hereditary chorea."Huntington's father and grandfather had both practiced medicine in the eastern end of Long Island for a period conjointly covering seventy-eight years, and had been acquainted with families in which chorea had existed for generations. Huntington believed that the disease existed almost exclusively on the eastern end of Long Island, where it was confined to a few families.