But cases of ai, ae, which arose later than the change to ei, ī, were unaffected by it; thus the nom. plur. of the first declension originally ended in -ās (as in Oscan), but was changed at some period before Plautus to -ae by the influence of the pronominal nom. plur. ending -ae in quae? hae, &c., which was accented in these monosyllables and had therefore been preserved. The history of the -ae of the dative, genitive and locative is hardly yet clear (see Exon, Hermathena (1905), xiii. 555; K. Brugmann, Grundriss, 1st ed. ii. 571, 601).
The diphthongs au, ou in unaccented syllables sank to -u-, as in inclūdō beside claudō; the form clūdō, taken from the compounds, superseded claudo altogether after Cicero’s time. So cūdō, taken from incūdō, excūdō, banished the older *caudō, “I cut, strike,” with which is probably connected cauda, “the striking member, tail,” and from which comes caussa, “a cutting, decision, legal case,” whose -ss- shows that it is derived from a root ending in a dental (see §25 (b) below and Conway, Verner’s Law in Italy, p. 72).
Consonants.—Passing now to the chief changes of the consonants we may notice the following points:—
23. Consonant i (wrongly written j; there is no g-sound in the letter), conveniently written ḭ by phoneticians,
(i.) was lost between vowels, as in trēs for *treḭes, &c. (§ 17. 6);
(ii.) in combination: -mḭ- became -ni-, as in veniö, from Ind.-Eur. *Ƨṷ mḭo, “I come,” Sans. gam-, Eng. come; -nḭ- probably (under certain conditions at least) became -nd-, as in tendō beside Gr. τείνω, fendō = Gr. θείνω, and in the gerundive stem -endus, -undus, probably for -enḭos, -onḭos; cf. the Sanskrit gerundive in -an-īya-s; -gḭ-, -dḭ- became -ḭ- as in māior from *mag-ior, pēior from *ped-ior;
(iii.) otherwise -ḭ- after a consonant became generally syllabic (-iḭ-), as in capiō (trisyllabic) beside Goth. hafya.
24. Consonant u (formerly represented by English v), conveniently written ṷ,
(i.) was lost between similar vowels when the first was accented, as in audīui, which became audiī (§ 17 [6]), but not in amāuī, nor in avārus.
(ii.) in combination: dṷ became b, as in bonus, bellum, O. Lat. dṷonus, *dṷellum (though the poets finding this written form in old literary sources treated it as trisyllabic); pṷ-, fṷ-, bṷ-, lost the ṷ, as in ap-erio, op-erio beside Lith. -veriu, “I open,” Osc. veru, “gate,” and in the verbal endings -bam, -bō, from -bhṷ-ām, -bhṷō (with the root of Lat. fui), and fīo, du-bius, super-bus, vasta-bundus, &c., from the same; -sṷ- between vowels (at least when the second was accented) disappeared (see below § 25 (a), iv.), as in pruīna for prusuīna, cf. Eng. fros-t, Sans, pruṣvā, “hoar-frost.” Contrast Minérva from an earlier *menes-ṷā, sṷe-, sṷo-, both became so-, as in sorōor(em) beside Sans. svasār-am, Ger. schwes-t-er, Eng. sister, sordēs, beside O. Ger. swart-s, mod. schwarz. -ṷo- in final syllables became -u-, as in cum from quom, parum from parṷom; but in the declensional forms -ṷu- was commonly restored by the analogy of the other cases, thus (a) serṷos, serṷom, serṷī became (b) *serus, *serum, *serṷi, but finally (c) serṷus, serṷum, serṷi.