IF we accept the view that species are such by virtue of segregation, and consider subspecies to be groups as yet imperfectly segregated, we seem logically bound to regard insular forms as valid species. According to this way of looking at the matter, a subspecies is in biology what a peninsula is in geography, while a species corresponds to an island. Hence it follows that many subspecies are far more widely distributed and for most purposes more important than many distinct species; just as many peninsulas are more important than the small islands off their coasts.