LONDONDERRY, or COLERAIN, a county of Ireland, in the province of Ulster. It is bounded on the south and south-west by the county of Tyrone; by Antrim on the east, from which it is parted by the river Bann; by Donegal, on the west; and that county and the Deucealedonian ocean, on the north. Its greatest length is about 36 miles, its breadth 30, containing about 251,510 acres. The bogs and heaths of this country are manured with sea-shells, as those of Donegal. Like that too, it is pretty champaign, and not unfruitful. It is particularly noted for a very clear river called the Bann, abounding with salmon, a fish said to delight in limpid streams. This river, to distinguish it from a lesser of the same name, is called the Greater or Lower Bann. In order to cultivate, settle, and civilize this county, king James I. granted it, by letters-patent, to a society, by the name of the Governor and Assistants at London of the new plantation of Ulster in the realms of Ireland. It contains six baronies; and, besides the two knights of the shire, sends to parliament two members for the city of Londonderry, and two each for Coleraine, and Newton-Lima-vady or Lamnevady.