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Rh cotylosaur reptiles in early Permian times. The ilium of the rhachitomous forms is not dilated above, as in the reptiles, but even this distinction fails in the more nearly allied embolomerous Cricotus, in which the ilium is prolonged backward, quite as in the reptiles. The pubes and ischia meet in a close symphysis without openings of any kind, except the pubic foramen, a small hole through the pubis below the margin of the acetabulum, in front of the ischiatic suture, for the passage of the obturator nerve. This "plate-like" structure of the pelvis is characteristic of the Cotylosauria (Figs. 114, 115), and more or less of the Theromorpha (Figs. 114 , 117), Therapsida (Fig. 119), Proganosauria, the Choristodera, and early Rhynchocephalia.



. 114. Pelvic girdles: A, Cacops (Temnospondyli), from below. One half natural size. B, Seymouria (Cotylosaur), from below. A little more than one half natural size. C, D, Varanops (Theromorpha), below and from the side.