Fig. 1. (A) X-ray of hindquarters of female Sminthopsis douglasi. (B) Diagram of pelvic region showing insertion of the ilio-marsupialis muscle (IMM) on the anterior iliac spine (AIS) and the passage of muscle through the inguinal canal (IC). The epipublic bones (EP) are embedded in the abdominal musculature. After passing through the inguinal canal, the ilio-marsupialis muscle divides into four branches, each passing to one of the four nipples on the same side. (C) Diagrammatic representation of the pouch. The broken line indicates the limit of the pouch area, and the solid line indicates the free edge of the fold of skin at the entrance to the pouch. The nipples, which lie under the pouch skin fold, are shown as small open circles.