CWM-TWRCH, a hamlet, in the parish of CAYO, higher division of the hundred of CAYO, county of CARMARTHEN, SOUTH WALES, 11 miles (N. W. by W.) from Llandovery. The population is returned with the parish. An old Roman road, called Sam Helen, leading from Llanio to Llanvair ar y br'n, can be traced here through the valley of the Twrch. The declivities of the hills are well wooded, especially where the Twrch falls into the Cothi; and the road from Llandovery to Lampeter passes along the left bank of the former stream.