and elaboration of Hirt’s. Apart from the Welsh examples the section contains nothing new except the notes on the place of a in the system (v (2)) and the treatment of long diphthongs (vii (5)). In the discussion of philological questions generally my obligation to Brugmann’s great work is so obvious as hardly to need statement; for the writing of prehistoric forms his scheme has been adopted, and is departed from in only one particular: ₑr, ₑn etc. are used here, as by Hirt, instead of r̥r, n̥n etc. I have also learnt much from Meillet’s brilliant Introduction, and have borrowed from him the convenient use of the term “sonant” to denote the sounds which oscillate between vowels and consonants in Pr. Ar. In the search for the origin and cognates of Welsh vocables I have made extensive use of Walde’s Wörterbuch, which contains, in a concise form and fully indexed, a vast collection of the results of recent investigation in this field; Boisacq’s Dictionnaire I have also found most valuable. For the purposes of Keltic philology I have consulted with much profit Thurneysen’s admirable grammar of Old Irish. The sections treating of the derivation of sounds are fuller than they were originally intended to be; and with the material thus provided I was led further to attempt to trace to their origin all inflexions and important grammatical forms. But in order to save space I have generally given only the explanation which seemed to me in each case the most probable; thus the fact that Pedersen’s equation of W. ynteu with Ir. intī or his derivation of eiδ-aw from *esi̯o is not mentioned does not necessarily mean that it has not been considered, but that I regard it as less likely than the explanation offered in the text.
I have to express my gratitude to Dr. Gwenogvryn Evans, who was kind enough to lend me for the purposes of this work his manuscript referred to as tr., his transcripts of numerous poems by G.Gr., G.Gl., Gu.O., D.N., D.E., H.D., I.F. and Ỻ., and to furnish me with proofs of w.m. before it was issued, and of r.p.
