Three rare portraits of family members of Charles Darwin will go on sale in London at a Sotheby's auction of early British paintings on July 9.
The paintings, by leading portrait artist Joseph Wright, have a combined estimate of 290,000-410,000 pounds.
The portraits depict Darwin's grandfather, the consultant and physician Erasmus Darwin (1731-1802); his uncle William Alvey Darwin (1726-1783) and also uncle's wife, Jane Darwin (1746-1835) with their son, William Brown.
The portrait of Erasmus, an oil on canvas in the original fluted British Marratta gilded frame, is estimated at 100,000-150,000 pounds. It was painted in 1770, the time when Erasmus' medical practice dominsated his life and he travelled extensively to treat patients.
The Jane-William painting has an estimate of 150,000-200,000 pounds while the portrait of William Alvey is estimated at 40,000-60,000 pounds.