Board Thread:Speculation House/@comment-226878-20140806000834/@comment-226878-20140810200252

I originally spelled the plural of Ursa as ursae as that had been the way I had grown up learning Latin (proxy through the study of species all given Latin designations). In my experience, words ending in -us like dominus in plural would end in -i (domini, as in Anno Domini). Words ending in -a like antenna would end plural in -ae (antennae). I did recently discover an exception to this, but I don't remember which word it was. But it did end in -a singular and then in -i plural.