140 TEXT-BOOK OF ZOOLOGY 



(b) The thorax receives additional support from the ribs, which are 

 completely ossified, even to their lower (sternal) segments, which in 

 mammals remain cartilaginous (see, however, bat), and from processes, 

 the so-called uncinate processes, one of which arises from the posterior 

 margin of each rib, and is applied to the rib next in succession behind. 



Skeleton hf the Golden Eagle, with the Body sketched in Outline. 



U., Mandible; Qu., quadrate bone; J., jugal bone; Hw., Bw., Sch.AW, cervical, dorsal and 

 caudal vertebra ; Ra., coracoid ; G., furcula ; B., sternum, with (BK.) sternal crest; 

 R., ribs; Be., pelvis; 0., humerus; Sp., radius; E., ulna; Hw., carpus; Jl., meta- 

 carpus ; I., II., III., digits of the fore-limb : the same letters and IV. denote those of hind- 

 lirnb; Osch., femur; Sch., tibia; W., fibula ; L., tarso-metatarsus. 



(c) The connection of the wings with the thorax by means of the 

 shoulder-girdle, although very light and free (why is this necessary?), 

 is nevertheless exceedingly strong. In mammals the shoulder- joint is 

 placed only between the humerus and the shoulder-blade, or at niost has 



