Scilly Islands, a group at the W. entrance of the English channel, belonging to the county of Cornwall, about 30 m. W. S. W. of Land's End; lat. of the lighthouse on St. Agnes, 49° 53' N., Ion. 6° 20' W.; pop. in 1871, 2,090. The group is circular, about 30 m. in circumference, and contains about 140 islands and islets, besides numerous rocks. St. Mary's, Tresco, St. Martin's, St. Agnes, and Bryher are the only ones with more than 100 inhabitants. They have steep and bold shores, on which many ships have been wrecked; but between the islands the water is shallow, and some of them are connected by strips of land at low water. The inhabited islands have an aggregate area of about 3,500 acres, but the soil is generally barren, and trees grow only in sheltered spots. Some oats and potatoes are raised on St. Mary's, and there is a little pasture land on the others. The inhabitants are mostly fishermen, pilots, and sailors. The local government consists of a court of 12 principal inhabitants presided over by a military officer.

The largest of the group is St. Mary's, with the capital, Hughtown. On the W. side of the island is Star Castle, and a garrison with numerous batteries. - The Scilly islands are generally supposed to be the Cassi-terides or Tin islands of the ancients; but as that metal is not now found upon them, it is thought that the western extremity of Cornwall was also included under that name. The group was sometimes used by the Romans as a place of banishment, and was called by them Sellinoe or Silurum insuloe. They were annexed to the English crown in the 10th century.