86 



ESSENTIALS OF ZOOLOGY 



a pair of riblike transverse processes to which muscles are attached, 

 and a dorsal projection is the neural spine. In addition, the neural 

 arch has at each end a pair of processes known as zygapopJiyses by 

 which the vertebrae are coupled together, the posterior zygapophyses 

 of one vertebra overlapping the anterior zygapophyses of the succeed- 

 ing one. This arrangement furnishes a protected canal for the spinal 

 cord and a firm axial support which also allows bending of the body. 

 The spinal nerves emerge between vertebrae through an intervertebral 

 foramina protected by the cartilaginous pads between the vertebrae. 



js- -^^^ Episternum 



-fc-^i'=s=^^=^ — Omosternum 



Epicoracoid 

 Corb'ilaqe 



Mesosternum 



T#-^^ Xiph'isternum 



Fig. 27. — Ventral view of the pectoral girdle of bullfrog in natural position. 



Appendicular Skeleton. — The anterior portion of the appendicu- 

 lar skeleton is composed of the pectoral girdle, sternum, and bones 

 of the forelimbs. The posterior portion has the pelvic girdle and 

 bones of the hindlimbs. 



The pectoral girdle and sternuni furnish a support and place of at- 

 tachment for the forelimbs and their muscles. They also provide a 

 case to protect the heart, lungs, and other organs in the anterior part 

 of the body. This girdle is not connected to the vertebral column. 

 Each side of the dorsal part of the girdle is composed of a large flat 

 bone, the suprascapula, which curves ventrally and joins the scapula. 



