Notes on Place-names GOSTON: TRE-OS In the previous volume of this journal (XXVII, 59-65) attention was drawn to the substitution in Glamorgan place-names of W tref for the affixed English element -ton, OE tun, in its various possible senses, as in Trefflemin for Flemingston, Trelales for Laleston etc. In the majority of such examples the post-Norman forms in -ton are the original settlement names and they occur in the Englishries of the Vale of Glamorgan and Gower. One difficulty lies in seeking to ascertain precisely when the Welsh forms become current for although in the Vale, in particular, it is strongly suspected that 'recolonisation by the [Welsh] language of the anglicised area' occurred from about the fourteenth century onwards, the circumstantial evidence for this is less tangible than it becomes by the late fifteenth and sixteenth centuries (v. ante XVI, 19-22). The same is true, by and large, where the evidence of place-name forms is concerned, recorded evidence before the sixteenth century being far less plentiful than in the later period. However, the toponymist is interested not only in the original form and meaning of a name but also in the various phases of its development and the influences that have been responsible for the modification of its form over the years. That development must be understood before the original form can be ascertained and identified with confidence. An example which illustrates this point would seem to be the name which now has currency on modern maps and road-signs in the form Treoes, at present a small village in the parish of Llan-gan verging on the modern complex of the Waterton Industrial Estate in the Ewenni valley, formerly a so-called 'manor', part of the estate of the Norris family in the thirteenth century, held with Pen- llin and Llan-gan, and in the possession of Jenkin Turberville at the time of his death in 1597. The following collected forms, as yet not as exhaustive a list as may prove possible at some future time, and the documentary sources from which the forms have been gleaned, provide enough information to identify the name as the Goston of sixteenth-century and later documents. That evidence also indicates the probability that the name has undergone two phases of influence in the process of cymricisation.