An account is given of the external morphology of the post-embryonic developmental stages of Spinturnix myoti Kol. (family Spinturnicidae) with particular reference to the ontogenetic development of the idiosomal, gnathosomal and leg chaetotaxy. Development from the egg through a prelarval stage to the protonymphproceeds in -utero and the protonymph is born in a fully developed form. The deutonymphal stage shows distinct ’sexual’ dimorphism. There is no larval form comparable to that normally present in the life-cycle of the Gamasina although the larval stage may be represented by the so-called prelarva. The extent and significance of the adaptations to ectoparasitism within the Spinturnicidae are discussed.