Cornovii (Cornwall) Dumnoniorum (present day Exeter), it is likely that he only listed Roman places, not purely native sites. Of these, there has been speculation that Voliba might be a place in Cornwall and Tamara is assumed to be on the River Tamar, the border between Cornwall and Devon. Ptolemy's list is supplemented by the problematical Ravenna Cosmography, which lists sixteen names before Isca Dumnoniorum (which is listed as "scadum namorum", showing some of the problems of this source) and which have therefore been assumed to be west of Exeter. Several have been identified as most likely in Devon, leaving "purocoronavis" (the
Isca Augusta three permanent legionary fortresses in later Roman Britain and, unlike the other sites at Chester and York, its archaeological remains lie relatively undisturbed beneath fields and the town of Caerleon and provide a unique opportunity to study the Roman legions in Britain. Excavations continue to unearth new discoveries on the extent and nature of the site. One of the most exciting discoveries is a complex of very large monumental buildings outside the fortress between the River Usk and the amphitheatre. This new area of the "canabae" was previously completely unknown. The Brythonic name "Isca" means "water" and refers to the