505. The nominative and accusative plural masculine and feminine have
rarely #-īs#, like stems in #-i-#: as #sacerdōtīs#, _priests_;
#meliōrīs#, _better_. For #-ā# in neuters in old Latin, see 130, 2.
506. The genitive plural of stems in #-tāt-# (262) is sometimes #-ium#,
like that of #-ī-# stems: as, #cīvitātium#, _communities_;
#voluptātium#, _pleasures_ (Cic.); but chiefly in or after the Augustan
age. #mēnsis#, _month_, has #mēnsum#, but often #mēnsuum#, sometimes
#mēnsium#. #āles#, _bird_, has sometimes #ālituum# in hexameter verse.
For the dative and ablative #-būs#, see 2505.