The Comparative Morphology of the Pelvis and Hind Limb of Japanese Muroidea. I. The Morphological Changes of the Pelvis and Hind Limb with the Growth of Japanese meadow Vole. Y.KANEKO (Zoological Institute, Faculty of Science, Kyoto University, Kyoto). Zool. Mag.77 : 367-373 (1968). The morphological changes of the pelvis and hind limb of Japanese meadow voles (Microtus montebelli) were observed at various stages of their growth. From the results obtained, following tendencies were revealed: 1) In the early stage of the postnatal growth, morphological difference of pelvis between male and female animals could hardly be observed. 2) The time of the first appearance of the sexual difference at pubic and ischiatic area coincided with the time when the sexual difference in the body weight was first recognized. 3) More extensive growth change was observed in female than in male animals; for instance, the severance of the pubic symphysis was observed only in female at a definite stage which seemed to be related with the pregnancy. 4) The well-developed tuberosity, crest and ridge of some bones in both sexes would be attributed to fossorial life of the vole.