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THE PECTORAL AND PELVIC GIRDLES
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the lowest living mammals, of which Ornithorhynchus and Echidna are the only examples, there are in addition to the clavicles three well-developed bones on each side, the scapula and two bones articulating with it at its lower end, the anterior of which, originally named epicoracoid by Cuvier, is generally known as the procoracoid; the posterior one helping to form the articulation for the arm bone, known as the true coracoid.
Fig. 96. Pectoral girdles: A, Cacops (Temnospondyli), from above. One half natural size. B, Seymouria (Cotylosauria), from below. One half natural size. C, Diadectes (?), from below. One half natural size. D, Varanops (Theromorpha), from above. One half natural size.
The homologies of these, or rather of
