LIMBS OF VERTEBRATES. 



31-5 



Fig. 373.— Diagram of a Vertebra 

 with its Dody {5), rib (7), breast-bone 

 (6) ; 1, neural spine; 2, 3, fore and 

 hind oblique processes ; 4, transverse 

 processes. 



bodies of eacli yertebra of a lizard, bird or mammal being 

 solid bone. Figs. 370 and 371 represent the relations of the 

 notochord in an adult lamprey and a young fish. 



The vertebra of a bony fish 

 or higher vertebrate consists 

 of a lody, with a dorsal or 

 neural spine ; a pair of oblique 

 processes (zygapophyses) arching 

 over and enclosing the spinal 

 cord ; and transverse processes, 

 bending downwards, to which 

 the ribs are articulated ; certain 

 of the thoracic ribs uniting 

 with the sternum or breast-bone 

 (Figs. 372 and 373). 



Vertebrae like those of fishes, 

 which are hollow or concave at 

 each end, are .said to be amphicoelous ; those hollow in front 

 and convex behind procmlous, as in most toads and frogs 



and crocodiles, and most existing 

 lizards, and those convex in front 

 and concave behind opisthoecelous, 

 as in the garpike, some Amphib- 

 ians (the salamanders and cer- 

 tain toads, Pipa and Bombinator). 

 Vertebrates never have more 

 than two pairs of limbs, an an- 

 terior and hinder pair ; the pecto- 

 ral pair of fins of fishes represent 

 the fore limbs of Amphibians and 

 higher Vertebrates, and the arms of man ; the two ventral 

 fins represent the hind legs of higher Vertebrates, and the 

 legs of man. Each pair of limbs is connected by ligaments 

 and muscles to a girdle or set of bones, called respectively 

 the shoulder girdle and pelvic girdle, each girdle being con- 

 nected by muscles to the vertebral column. The shoulder 

 girdle consists of a clavicle (or collar-bone), scapula (or 

 shoulder-blade), and coracoid bone, usually a process of the 

 scapula. These bones differ greatly in the different classes. 



Fig. 373.— Tlioracic vertebra of 

 buzzard (Buteo vulgaris), c, centrum 

 or body ; s, superior spiutius pro- 

 cess ; tr^ transverse process ; m>, 

 rib ; o, tuberculum of the rib ; /?, ca- 

 oitulnm of the rib.— After Gegen- 

 baur. 



