[TERMINOLOGY]
Skeleton
The majority of the osteological terms used in the present paper are those used by Howard (1929); however, many skeletal features are not named by Howard. Since names for most of these parts were not found in the other literature examined, it was necessary for me to propose terms for them. Most of this new terminology pertains to the pelvis. All of the osteological terms used in the present paper, whether used by Howard or not, are briefly defined below. Those of the pelvis are illustrated in [Fig. 1]. Most of the remaining terms are illustrated by Howard (1929).
Pelvis
The median dorsal ridge is the blunt ridge in the midline of the anterior part of the synsacrum formed by the neural spines of the vertebrae. The antitrochanter, on the posterodorsal rim of the acetabulum, is a pyramid-shaped projection that articulates with the proximal end of the femur. The anterior iliac crest is a ridge along the dorsomedial border of the ilium, beginning almost at the anterior end of that bone; the crest curves laterally as it extends posteriorly and (for purposes of the present definition) ends at the level of the posterior edge of the antitrochanter, where the crest is continuous with the lateral iliac process. The lateral iliac process is a pronounced, laterally or ventrolaterally, projecting ridge on the ventrolateral surface of the ilium posterior to the level of the antitrochanter; the process does not extend as far as the posterior end of the ilium. The lateral ischiatic ridge is a relatively slight ridge continuous with the posterior end of the lateral iliac process and curves posteroventrally across the lateral surface of the posterior part of the ischium; the ridge extends to the ventral edge of the ischium in some individuals and not in others. The dorsolateral iliac ridge begins at the lateral edge of the ilium near the posterior end of the lateral iliac process and curves posteromedially and somewhat dorsally, extending to the posterior edge of the ilium. The lateral iliac fossa is the concavity below the overhanging lateral iliac process. The ilio-ischiatic fenestra is a large oblong opening behind the acetabulum between the ilium and the ischium. The obturator foramen is a small oval opening posteroventral to the acetabulum between the ischium and the pubis. The ventral ischiatic tubercle is the angle formed by the ventrally projecting ischium at the point (near its midlength) where the ischium overlaps and lies lateral to (and fused to) the pubis. The pectineal process is an anterolaterally directed projection of the ventrolateral edge of the ilium anteroventral to the acetabulum. The femoral notch of the ilium is a shallow notch in the ventrolateral edge of the ilium approximately halfway between the last rib and the pectineal process. The oblique iliac crest is a pronounced blunt ridge on the ventral surface of the ilium and extends from the posterolateral corner of the last synsacro-thoraco-lumbar vertebra to 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.
Fig. 1. Pelvis of Tympanuchus pallidicinctus. A. Lateral view. × 1. B. Ventral view. × 1⅛.