258 



THE PIGEON 



forms the vertebra-arterial canal, through which a vertebral arteiy runs. The 

 centra of these vertebrae have saddle-shaped surfaces, the anterior face being 



Head 



JTrochanter 



Femur- 



1, 'Patella 



Cnemial process 



Tibio-tarsus- 



f-Fibula 



Phalanges of, 

 IsfDigit'---- 



1st Metatarsal 



-Tarso-metatarsus 



Tifhalanges of 

 ,'j',lth Digit 



Fig. 90.— The Hind-limb of the Pigeon {Ooi 



concave from side to side and convex from above downwards, the posterior face 

 convex from side to side and concave from above downwards. This type of 

 vertebra is termed heteroccelous. The ribs of the last two cervical vertebrae 

 are not rudimentary, and the heads are not fused with the vertebrae. 



(a) The Atlas is the first cervical vertebra. It has no distinct centrum ; 

 it is ring-like. On its anterior surface ventrally it bears a smooth 

 articular facet for the single occipital condyle of the skull. 



