^ntumlBjifa €mhntim. THIRD SERIES, No. LIIL—JANUARY, 1868. ANCIENT ARWYSTLI. The old historical cantref of Arwystli previous to the time of Henry VIII formed part of Meirionydd, and included the three commots of Uwch-coed, Is-coed, and Gwerthrynion, but by the statute passed in the twenty- seventh year of that monarch's reign, the latter commot, which included five extensive parishes, was to form part of the new county of Radnorshire, and the remain¬ ing portion of the cantref was taken from Meirionydd to constitute a part of Montgomeryshire. These two commots form the ecclesiastical deanery of Arwystli, and the modern hundred of Llanidloes, embracing within their limits the seven parishes of Llangurig, Llanidloes, Trefeglwys, Llandinam, Carno, Llanwnog, and Pens- trowed. Some of the ancient remains in these parishes, forming the south-western portion of Montgomeryshire, are the subject of the present paper. That portion of Arwystli lying to the north of the Severn was, in the time of the Britons, peopled by a portion of that nation or collection of tribes which went under the generic name of Ordovices. According to Camden they were so called because the River Dyfi ran through their territory — " Ar-Dyfi" — upon the Dyfi, but a later1 writer is more happy in his conjecture, that the Ordo¬ vices were so denominated in allusion to their mouri- 1 The late Eliezer Williams. 3UD SER., VOL. XIV. 1