CAERSEDDVA (CAER-SEDDVAN), a township, in the parish of DiaowEN, hundred of MACHYNLLETH, county of MONTGOMERY, NORTH WALES, 61 miles (B. N. E.) from Machynlleth, containing 475 inhabitants. This township, the name of which signifies the " session fortress," forms the upper and north-eastern portion of the parish, and is in general rugged and mountainous. There are several lead mines in different parts, but they are only partially worked.