こがしらねずみいるかであれば
小頭鼠海豚であれば
kogashiranezumiirukadeareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of こがしらねずみいるか

1. If it were a small-headed dolphin; If small-headed dolphins existed

Ba Conditional
Usually Written in Kana