402 DEVELOPMENT OF OEGANS IN MAMMALIA. [CHAP, 



Fig. 135. 



Longitudinal Section through the Intervertebral Liga- 

 ment AND ADJACENT PARTS OF TwO VbRTBBR^ FROM THE 



Thoracic Region op an advanced Embryo of a Sheep. 

 (From KoUiker.) 



la. ligamentum longitudinale anterius ; Ip. ligamentum long, pos- 

 terius ; li. ligamentum intervertebrals ; h, V. epiphysis of 

 vertebra ; w. and id. anterior and posterior vertebrae ; c. in- 

 tervertebral dilatation of notoohord ; c' and c". vertebral di- 

 latation of notochord. 



The early changes in the development of the visceral 

 arches and clefts have already been described, but the 

 later changes undergone by the skeletal elements of the 

 first two visceral arches are sufficiently striking to need 

 a special description. 



