Internal fertilization is universal in chondrichthyan fishes and, as such, requires a suite of biological activities, including behavioral, morphological and physiological mechanisms, to ensure successful copulation and fertilization. This volume correlates available data and ideas concerning the development, reproductive morphology, function, and phylogeny of chondrichthyan fishes. Coverage includes oogenesis, spermatogenesis, gestation, regulation of reproductive tract function, sperm storage, nutrient provision, placentation, and phylogeny. New and exciting data is presented including the idea that yolk sac viviparity is the plesiomorphic state rather than oviparity.