Scanning electron micrographs of the hinges of Indosphenia species. a chondrophore of I. abbreviata typical form from Port Canning b as a but from narrow form c as a but from distorted form d chondrophore of syntype of Cuspidaria annandalei e chondrophore of I. sowerbyi from Adyar f as e but from Cooum g right valve pseudo tooth in I. abbreviata h right valve pseudotooth in syntype of Cuspidaria annandalei i right valve pseudotooth in I. sowerbyi j–k chondrophores in small and large specimens of I. kayalum l–m right valve pseudo tooth small and large specimens of I. kayalum n–o chondrophore and right valve pseudo tooth of I. cochinensis. Scale bar: 5 mm.