Pelvises vary in size and shape and have been classified into four parent groups, according to the shape of the brim. 1. The Gynaecoid, or true female pelvis, has a round brim. 2. The Android has a heart-shaped brim. 3. The anthropoid has an oval brim, narrow in the transverse. 4. The Platypelloid, or simple flat pelvis, has a kidney-shaped brim, narrow in the antero-posterior diameter.