PLATE III. 



Fig. 10. Longitudinal section through the axial region at the base of the tail of 

 a specimen of Amia 30 mm. long. Shows especially, on the right hand, the upper 

 and the lower intercalated cartilages; on the left hand, the interposition of the upper 

 intercalated cartilages between the bases of the upper arches and the notochord; 

 while the intercalated cartilages are wanting between the bases of the lower arches on 

 the left hand. 



Fig. 11. Side view of a portion of the dorsal region of the vertebral column of 

 Adpenser. Shows bases of upper and lower arches and the cartilages intercalated 

 between them ; also between the two series of arches an uncovered portion of the 

 notochord. 



Fig. 12. Cross-section through a posterior dorsal vertebra of an Amia 23mm. 

 Shows especially the situation of the earliest points of ossification. 



