Supernumary or vestigal mammae may occur anywhere along the mammary line extinding from axilla to groin. Among lemuroids, however (cf. Shultz 1948), usually one but frequently up to three well-developed mammary pairs are pectoral (including axial), one pair abdominal and one or two pairs inguinal.
1977, Philip Hershkovitz, “4 Some Descriptive, Diagnostic, Quasi-diagnostic, and Primitive Mammalian Characters of Living Primates”, in Living New World monkeys (Platyrrhini) - with an introduction to Primates, volume 1, Mammae, page 18