CHAPTER XIV. 



THE SHOULDER GIRDLE. 



Having finished the consideration of the axial portions of 

 the skeleton, we now turn to the appendicular parts, which 

 consist of two pairs of limbs, anterior and posterior. 



The anterior limb is present, and fully developed, in all 

 Mammals, being composed of a shoulder girdle and three 

 segments belonging to the limb proper, viz. the upper arm 

 or brachium, the fore-arm or antibrachium, and the hand or 

 menus. 



The Shoulder Girdle in the large majority of Mammals 

 is in a comparatively rudimentary, or rather modified, con- 

 dition. Its true structure and its relations to the pelvic 

 girdle can only be understood by a reference to its condition 

 in the lower vertebrates. 1 



Each side of the girdle consists primitively of a curved 

 rod of cartilage, placed vertically (in the horizontal position 

 of the body), the upper or dorsal end being free, v the inner 

 side lying upon, though not united with, some of the anterior 

 thoracic vertebrae or ribs, and the inferior or ventral end 

 being attached to the side of the presternum. 



1 On this subject see W. K. Parker's valuable work before cited, and 

 also Gegenbaur's " Untersuchungen zur Vergleichenden Anatomie," 2 tes 

 Heft, 1865. 





