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CHAPTER IV
THE PECTORAL AND PELVIC GIRDLES
The Pectoral or Shoulder Girdle
(Figs. 95–113)
Fig. 95, Diadectes (Cotylosauria). Pectoral girdle, right side.
Those bones which form the framework for the support of the anterior extremities in vertebrate animals are collectively called the pectoral or shoulder girdle. In our own skeleton, as in that of most mammals, there are but two on each side, the scapula, or shoulderblade, and the clavicle, or collar-bone. A third bone, or possibly two, on each side, are represented in most mammals by mere vestiges, which early unite with the scapula to form the coracoid process. In
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