Abstract
SYNOPSIS: Ultrastructural and protargol studies reveal that the trophont of Lagenophrys callinectes, though highly specialized, generally conforms to the basic peritrich structural pattern.Features described for L. callinectes trophonts which are unique for the genus are the fine structure and arrangement of the lorica and lips, the attachment organelle of the peristomial cytoplasm, its attachment to the loricastome walls, and the arrangement of the aboral kinetosomes of the trophont. Lack of a distinct scopularized region, and of a ventral lorica wall also characterize L. callinectes trophonts.The 4‐row terminal peniculus, as revealed by protargol staining, differs from the 6‐row terminal peniculus of L. nassa suggesting that the patterns of infundibular structure, as revealed by protargol, should be useful in future taxonomic studies of Lagenophrys species.