SHOULDER BLADE AND LOCOMOTION 



37 



the spine, the prescapular lamina, is most extensively developed in 

 such animals as per- 

 form complex move- 

 ments with the fore- 

 limhs. The Sea Lion 



and the Great Anteater 

 are cited by Professor 

 G. B. Howes as ex- 

 amples of this pre- 

 ponderance of the an- 

 terior portion of the 

 scapula over that which 

 lies behind the spine. 



The O'eneral shape of ^^'^' ^^' — ^^S^^ scapula of Dolphin (Tursioiis tursio). 

 ^ X J. a. Acromion ; a/, prescapular fossa ; c, cora- 



coid ; gc, glenoid cavity ; pf, postscapular ibssa. 

 (From Flower's Osteology.) 



the scapula varies con- 

 siderably among the 

 different orders of mammals : 



but it always presents the characters 

 mentioned, which are nowhere seen 

 among the Sauropsida except among 

 certain Anomodonts, which will be 

 duly referred to (see p. 90). The 

 most conspicuous divergences from 

 the normal are to be found in the 

 Cetacea and the Monotremata. In 

 the former the acromion is approxi- 

 mated so nearly to the anterior 

 border of the blade-bone that the 

 prescapular fossa is reduced to a 

 very small area ; and in Plaianista 

 the acromion actually coincides 

 with the anterior border, so that 



In 



Fig. 28. — Side view of right half of 



shoulder girdle of a young Echidna that fosSa actually disappears. 



{Echidna hystrix). 

 mion ; c, coracoid ; 

 border ; c/, clavicle ; 

 scapular suture ; ec, epicoracoid ; 

 glenoid border ; gc, 



% TOrtcoki ^^^ Whales, too, the scapula is as 



CSS, coraco- a rule very broad, especially above ; 



"glenoid ^^ ^^^ frequently a fan-like contour. 



cavity ; ic, interciavicie ; pf, post- In the Mouotremata the acromion 



scapular fossa; jjs, presternum; .<, i • 'j -ii ii_ l 



spine ; ss, suprascapular epiphysis ; also COmCldeS With the anterior 



ssf, subscapular fossa. (From border of the scapula ; but the 



Flower's Osteology.) „ i • i .. 



sameness oi appearance which it 

 thus presents (in this feature) to the Cetacean scapula is appar- 



