72 THE STRUCTURE OF MAN 



muscles, but its original independence and greater significance is 

 seen in the fact that it ossifies from two distinct centres, which 

 in Man only completely fuse with one another and with the 

 bony scapula after the sixteenth to the eighteenth year. [This 

 double ossification of the coracoid occurs only in Mammals 

 among living Vertebrates^ The overhanging portion of the 

 coracoidal region of the human blade -bone, which (co., Fig. 

 52) from its suggestiveness of a bird's head has been termed 

 the " coracoid process," answers in 

 every detail of relationship to the 

 epicoracoid of the lowest Mammals 

 (ex., Fig. 28). The basal portion, or 

 second coracoidal element (which 

 does not appear in the human sub^ 

 ject until the fourteenth or fifteenth 

 year), represents, in a highly reduced 

 and vestigial condition, the more 

 robust element of the Ornithorhyn- 

 chus coracoid (m.c., Fig. 28). It was 

 FIG. 52,-RiGHT BLADE-BONE OP A until recently known as the " cora- 

 NEW-BORN CHILD, SEEN FROM THE coid"; but, as it and the epicoracoid 

 INNER OR COSTAL SURFACE. ,-, ,,, , . . n 



co., coracoid process ; the dark spot to g ether *>premt the entire coracoid 

 at os. represents the first of its two of the lower Vertebrata, the term 

 metacoracoid is now applied to it.] 1 

 The scapula is in Man a broad 

 bone, its form being doubtless attained in functional adaptation to 

 a very strongly developed shoulder musculature. In those lower 

 animals, in which the anterior limbs are simple ambulatory organs 

 performing less complicated movements, the scapula is not so broad, 

 especially at its median and hinder border the so-called base. It 

 is therefore very interesting to be able to prove, both by the 

 Anatomy of the lower races (Negroes and aborigines of Australia) 

 and by .human Ontogeny, that the great breadth of the median 

 part of the human scapula, and the sharper differentiation of its 

 spine, may both be considered as secondarily acquired features, 

 which stand in direct relation to the gradually increasing func- 

 tional activity of the fore-limb. 2 



1 [Cf. Lyndekker and Howes, Proc. Zool. Soe., Lond. 1893, pp. 172 and 585.] 



2 [The scapula of the higher Mammalia differs most conspicuously from that of 



the lowest Mammals and all lower Vertebrates, in its expansion, cephalad of its spine, 

 to form the so-called prescapular lamina. This is but feebly formed in Man. It 



with marked specialisation of the 

 purpose. This is readily seen, for 



. n 



attains its highest development in association with marked specialisation of the 

 fore-limb not, however, always for the same purpose. This is readil 



