Both of the words you are having trouble with are actually accusative plurals and not genitives. Third declension nominative and especially accusative plurals are found very often in the ending -is
rather than -es
. The distinction between genitive and nom/acc plural is that the latter is a long I
and the former is a short I
. This also applies to participles and third declension adjectives.
It is unfortunate that Wheelock does not make this more clear, he only mentions it once or twice in the text (in the small print at the bottom of the page) and maybe a few times in the back.
If you don't have it already, Words
is an endlessly useful parsing program. If you had entered "hostis", one of the results would have been
host.is N 3 3 ACC P C
Meaning Noun, Accusative, Plural, C (variable gender)
Bello Persico Themistocles cum exercitu iter in hostis faciebat, cum duos gallos vidit in via dimicantis.
I would translate this something like...
In the Persian War, Themistocles was marching with his army against the enemy, when he saw two roosters fighting in the road.
flebile nescio quid queritur lyra, flebile lingua murmurat exanimis, respondent flebile ripae