In Ancylomia japonica ZELLER, the developmental process from revolution of the embryo to hatching can be divided into 7 stages. The morphogenesis at each stage is described. 1) The cardioblasts are the mesodermal origin. 2) Unrevolved embryo develops untill the formation of the setae. 3) Pronotum is derived from the epithelium of the head lobes. 4) The embryonic moulting is observed clearly.
