[1018.] (1 c.) Most verbs in -īre have the perfect stem in -v- ([869]), and the perfect participle in -tus, both preceded by a form of the present stem in long -ī-: as,
| audiō, hear | audīre | audīvī | audītus |
PERFECT STEM IN -u-.
[1019.] (2.) The following verbs in -īre have the perfect stem in -u- ([874]), and the perfect participle, when used, in -tus:
| am-iciō, don | am-icīre | am-icuī | am-ictus |
Perfect rare: once am-icuī (Brut.), once am-ixī (Varr.).
| ap-eriō, open | ap-erīre | ap-eruī | ap-ertus |
| op-eriō, cover over | op-erīre | op-eruī | op-ertus |
| saliō, leap | salīre | saluī | —— |
Compounds have i for a throughout: as, īn-siliō. A perfect system in -v- ([823], [893]), as ex-silīvī, occurs in late writers (Col., Sen., Plin., &c.).
DEPONENTS IN -īrī.
[1020.] (1 a.) The following deponents in -īrī have the perfect participle in -tus: