There are very few verbs that end in 'i' in English. The only one I can think of is 'to taxi'. Most English words that end in ' i' are adopted from other languages (wadi, campi, spaghetti, sari etc) or come from old Latin or Greek. Many of them are scientific words but most are nouns or adjectives. There are also very few verbs ending in 'c'. 'To panic' is one. Most words ending in 'c' come from old Latin or Greek. The majority of them are adjectives.

There are too many words ending in "i" to list. See here http://en.wiktionary.org/wiki/Category:English_irregular_plurals_ending_in_%22-i%22 Here are all the words ending in "c" http://words-that-end-in-c.worddetector.com/e/