Prosimian vs Strepsirrhine vs Haplorrhine

The difference between the previously widespread Prosimii/Anthropoidea classification of primates and the Strepsirrhini/Haplorrhini classification usually used nowadays lies with the position of the tarsiers. It seems fairly clear that tarsiers share numerous derived conditions with anthropoids, so the Strepsirrhini/Haplorrhini scheme reflects phylogeny, and the concept of Prosimii (vernacular prosimians) has no more than an old-fashioned, subjective grade significance. The history of the terminology, and of evolving taxonomic philosophies, has some bearing on the usage of these names and how they should be spelled.