According to the Merriam-Webster Dictionary, Perrine lemons are a hybrid between a Genoa lemon and either a Mexican or West Indian lime. They were first developed in Florida with the hopes of sustaining past diseases affecting citrus plants (via Specialty Produce). The resulting fruit is smaller in size and sort of squat, much more like limes in that way than lemons. They also ripen from green to yellow — though they may retain some of that green color even when ripened. They also have a high acidity level which makes them perfect for marinating seafood. Perrine lemons have a thin and smooth rind that is still tough and covered in little oil glands that give the lemon that quintessential textured feel.