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 articu- 



FiG. 96. Pectoral girdles: A, Cacops (Temnospondyli), from above. One half natural 

 size. B, 6'«'7OT0«r»<j (Cotylosauria), from below. One half natural size. C, Diadectes i^), 

 from below. One half natural size. D, Varanops (Theromorpha), from above. One 

 half natural size. 



lating 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. The homologies of these, or rather of 



