near the anteroventral border of the ilio-ischiatic fenestra. The _internal ilio-ischiatic crest_ is more or less continuous with the oblique iliac crest and extends posteriorly along the dorsal border of the ischium (forming the ventral border of the ilio-ischiatic fenestra), and then curves sharply dorsomedially onto the ventral surface of the ilium. The _iliac recess_ is a concavity dorsolateral to the sharply curving posterior end of the internal ilio-ischiatic crest. [Illustration: FIG. 1. Pelvis of _Tympanuchus pallidicinctus_. A. Lateral view. × 1. B. Ventral view. × 1-1/8.] The terminology applied to the synsacral vertebrae by different authors varies. The terminology proposed by DuToit (1913) is employed in the present account. See my fig. 1B. This terminology differs considerably from that used by Howard (1929). DuToit divides the fused synsacral vertebrae into the following five groups, listed in anteroposterior sequence: (1) _synsacro-thoracic_, which bear movable ribs; (2) _synsacro-thoraco-lumbar_, which lack movable ribs but possess well developed laterally directed parapophyses, in addition to the more dorsally directed diapophyses; (3) _synsacro-lumbar_, which lack parapophyses, although possessing inconspicuous diapophyses; these vertebrae are shortened anteroposteriorly and are so firmly fused together that often the number present can be determined only by counting the intervertebral foramina; (4) _synsacro-sacral_, which have much more pronounced transverse processes than do the synsacro-lumbar vertebrae; these transverse processes are expanded distally where they fuse with the ilium and represent both parapophyses and diapophyses partly or completely fused together plus sacral ribs (detectable only in the embryo); there are considered to be two of these vertebrae; they are situated at approximately the level of the acetabulum; (5) _synsacro-caudal_, which include the remainder of the fused vertebrae; no marked gross morphological features differentiate the synsacro-sacral and the synsacro-caudal groups of vertebrae. The boundaries between all but the last two groups of vertebrae are usually, but not always, easily determined. It may be difficult to determine whether a vertebra with rudimentary parapophyses belongs to the synsacro-thoraco-lumbar or the synsacro-lumbar group. Sometimes a parapophysis will be better developed on one side of a vertebra than on the other. FEMUR