[34] It is not improbable that anciently all feminine nouns, except a few irregular ones, added a syllable to the nominative, as _e_ or _a_, in forming the genitive. The translators of the S. S. have sometimes formed the genitive of feminine polysyllables in this manner, as sionagoige from sionagog, Mark v. 36, 38. But it appears more agreeable to the analogy of inflection that such polysyllables should now be written without an _e_ in the genitive.
[35] It is probable that this noun should rather be written àdh. See McFarlane's Paraphrases, III. 3. also Lhuyd and O'Brien, _in loco_.
[36] Derivatives in _an_, and _ag_ should form their genitive according to the general Rule, _ain_, _aig_; and in pronunciation they do so. When the syllable preceding the termination ends in a small vowel, the Rule of 'Caol re caol' has introduced an _e_ into the final syllable, which is then written _ean_, _eag_. In this case writers have been puzzled how to form the genitive. The terminations _eain_, _eaig_, would evidently contain too many vowels for a short syllable. To reduce this awkward number of vowels they have commonly thrown out the _a_, the only letter which properly expressed the vocal sound of the syllable. Thus from caimean m. a _mote_, they formed the gen. sing. caimein; from cuilean m. a _whelp_, g. s. cuilein; from duileag f. a _leaf_, g. s. duileig; from caileag f. a _girl_, g. s. caileig. Had they not yielded too far to the encroachments of the Rule of 'Caol re caol' they would have written both the nom. and the gen. of these and similar nouns more simply and more justly, thus: caiman, g. s. caimain; cuilan, g. s. cuilain; duilag, g. s. duilaig; cailag, g. s. cailaig.
[37] In many instances, the Plural termination _a_ is oftener written with this final _n_ than without it. When the vowel preceding the termination is small, the termination _a_ or _an_ is very needlessly written _e_ or _ean_, to preserve the correspondence of vowels.
[38] We are informed by E. O'C. that this is the usual construction in the Irish Dialect, and it appears to be the same in the Scottish. Thus, air son mo dhà shùl, _for my two eyes_.--Judg. xvi. 28. Ir. & Scott. versions.
[39] So in Hebrew, we find a noun in the singular number joined with _twenty_, _thirty_, _a hundred_, _a thousand_, &c.