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- 

 limbs. The Sea Lion 

 and the Great Anteater 

 are cited ])j l*rofessor 



Fig. 27 



Right scapula of Dolphin {Tursinjis turxio). 

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

 coiil ; gc, glenoid cavity ; j)f, postscapular fossa. 

 (From Flower's Osteology.) 



(t. 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 general shape of 

 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, wdiich 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 

 l)order of the blade-bone that the 

 prescapular fossa is reduced to a 

 very small area ; and in Platanista 

 the acromion actually coincides 

 ,.,,,, ^ with the anterior border, so that 



Fig. 28. — Side view of right half of n t 



shoulder girdle of a young Echidna that fossa actually disappears, in 

 ■ {Ediidna hystrix). x| a, Aero- ^j^^ Whales, too, the scapula is as 



mion : c, coracoid ; co, coracoul -^ 



border ; d, clavicle ; ess, coraco- a rule Very broad, especially above ; 

 scapular suture ; ec, epicoracoid ; -^ j frequently a fan-like contour. 



go, glenoid border ; gc, glenoid i -J 



cavity ; tc, interciavicie ; jj/, post- In the Monotremata the acromion 



"^rst^rJiX^i^^ '^'^° '=»™«1<'-^ ^"h the anterior 



ssf, subscapular fossa. (From border of the scapula ; 1)Ut the 



Flower's Ostevloriy.) p i • i -j. 



^ sameness ot appearance which it 



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



