LLANGAIN (LLAN-GAIN), a parish, in the higher division of the hundred of DERLLYS, union of CARMARTHEN and county of CARMARTHEN, SOUTH WALES, 4 miles (S. S. W.) from Carmarthen; containing 403 inhabitants. This parish is beautifully situated on the north bank of the river Towy, which is here navigable for ships of considerable burthen; and comprises a large extent of arable and pasture land, inclosed and in a good state of cultivation. The soil is extremely favourable to the growth of corn, of which great quantities are raised of a quality not surpassed by that of any other part of the principality; and the surrounding scenery is richly diversified, the views comprehending a portion of the beautiful Vale of Towy, with the ivy- mantled ruins of Green Castle overhanging the river, and other picturesque and pleasing features. The living is a perpetual curacy, endowed with £800 royal bounty; net income, £85; patron and impropriator, F. Bind-worth, Esq., whose tithes have been commuted for a rent-charge of £55. 18. The church, dedicated to St. Synin, is a neat edifice, occupying the summit of a lofty eminence above the Vale of Towy, which commands varied and extensive prospects over the surrounding country and the bay of Carmarthen. About 25 children are instructed in a day school at the expense of their parents; and 60 in a Sunday school gratuitously. Leland, describing the remains of Green Castle, says, "four miles from Llanstephan, on the same ripe, is a place or cliffe called Green Castle, where ships used to lie at anchor to which Camden adds, "it is also called Castle Mole, and supposed to be the Humphreys Castle of Dr. Powel, and built by Uchtred, Prince of Merioneth, A. D. 1138."