keinhauc b.b. 54 ≡ keinhawc b.t. 28; but the oldest Ml. prose mss. (the early mss. of the laws) and Mn. lit. W. follow the practice of the N. W. dialects and insert the i̯, as keynẏauc a.l. i 24 ms. a., cf. 22 mss. b., d., Mn. W. ceini̯og ‘penny’.
(2) There are, however, several exceptions to this rule besides those mentioned or implied in § 36. The i̯ is omitted before the substantival terminations ‑en, ‑es, ‑edd; as deilen (M.Ỻ. i 155 has the unusual deili̯en) ‘leaf’, bugeiles ‘shepherdess’, cyfeilles (printed cyfeillies in d.g. 75) ‘amie’, meithedd ‘lengthiness’; before endings of comparison, as meithed, meithach, meithaf (maith ‘long’), meined, meinach, meinaf (main ‘slender’), except rheit-i̯ed, ‑i̯ach, ‑i̯af § 149 i, stems in ‑eidd- as manweiẟẏach Ỻ.A. 8 ‘finer’, pereiddi̯af ‘sweetest’, and some stems in ‑eith- as perffeithi̯af ‘most perfect’; before the pl. endings ‑edd, ‑oedd, as ieithoedd ‘languages’; in a few isolated words as teilo ‘to manure’ (but teẏlẏaw in b.ch. 102), adeilad ‘building’ (but adeilẏat in r.p. 1220), cymdeithas ‘society’, eiddo ‘property’.
(3) Medial ei before a consonant originally simple must be due to affection by i̯ after the consonant; and the i̯ in ysbeili̯af etc. is the affecting i̯ preserved. ‑eith- generally represents *‑ekt- a verbal noun and adj. formation, as in perffeith ‘perfect’, and the i̯ in perffeithi̯o is probably analogical, § 201 iii (6). From these the i̯ has tended to spread. But there is necessarily no original reason for it when ei comes from ‑ek- or ‑eg‑; hence the exceptions meithach, cymdeithas, teilo (tail < *tegl- § 104 ii (1)), etc.
iii. i̯ is also added to many stems having i or u; as cil ‘back’, pl. cili̯au cili̯af ‘I retreat’; tir ‘land’, old poetic pl. tiri̯on b.b. 26, r.p. 1144, tiri̯o ‘to land’, tiri̯og ‘landed’ (but pl. tiredd, tiroedd); grudd ‘cheek’, pl. gruddi̯au; llun ‘form’, pl. lluni̯au, lluni̯o ‘to form’, lluni̯aidd ‘shapely’; ystudẏaw, llavurẏaw Ỻ.A. 11 ‘to study’, ‘to labour’. In some of these cases also the i̯ is lost in S. W. dialects.
iv. Many stems end in w̯ which forms rising diphthongs with the vowels of all endings, except with w § 36 i; thus galw̯ ‘to call’, galw̯af ‘I call’, gelw̯aist ‘thou calledst’, gelw̯ynt ‘they called’, etc.
§ 36. i. w̯ drops before w, and i̯ drops before i. The semivowel is sometimes written (as w or y) in Ml. W., but is often
