LECT. II.] 



SHOULDER-BONES OF DUCKBILL. 



girdle carries a pair of epi-pubic (or so-called Marsupial) 

 bones as in the Marsupials, in which they lie above or 

 within the pouch, so that their use is not very apparent, 

 for the "pocket" swings outside them. But their mor- 

 phology is evident, for the pelvis of the Salamander, 



FIG. 3. Shoulder-girdle and sternum (breast-bone) of Ornithorliynchus paradoxus, 

 two-thirds natural size, s.sc, supra-scapular region of scapula (shoulder-blade, sc) ; 

 m.sc, middle scapular region ; cl, clavicle; i.cl, inter-clavicle, cr, coracoid bone ; 

 e.cr, epicoracoid; gl, glenoid cavity, the head of upper arm-bone (humerus) ; 

 mb.s, manubrium (top or handle) of sternum; st, sternum; x.s, xiphoid end of 

 sternum ; v.r, lower part of vertebral rib ; i.r, intermediate rib (as in Lizards) ; 

 s.r, sternal rib. 



and also, indeed, that of the Skate, shows similar out- 

 growths of the pubic region of the girdle. 



But it is in the front cincture, or shoulder-girdle, that 

 we see the most remarkable signs of ancientness in the 

 Prototheria. The scapula in them does not give off a 



