VERTEBRAL COLUMN 



529 



xxi] 



consisted of a thin shell of bone surrounding the chorda, and 

 composed of the basidorsals and basiventrals, which met each 

 other, forming a broad-based section along the side of the vertebra, 

 both parjbaking in the formation of a transverse process which 

 "carried the rib. It is of course possible and even probable that 

 in these extinct forms dorsal and ventral intercalaries were present, 



FIG. 255. A. dorsal, B. ventral, and C. lateral view of the skull of a Newt, 

 Molge cristata x 2. After Parker. 



The cartilage is dotted, the cartilage bones are marked with dots and dashes, 

 the membrane bones are left white. 



1. Premaxilla. 2. Anterior nares. 3. Posterior nares. 4. Nasal. 

 5. Frontal. 6. Parietal. 7. Prefrontal. 8. Maxilla. 9. Fused 

 vomer and palatine. 10. Parasphenoid. 11. Orbitosphenoid. 



12. Pterygoid. 13. Squamosal. 14. Pro-otic region of fused exoccipital 

 and pro-otic. 15. Quadrate. 16. Calcified cartilage forming the 



articular surface of the quadrate. 17. Exoccipital region of fused 



exoccipital and pro-otic. 18. Articular. 19. Articular cartilage. 



20. Dentary. 21. Splenial. 22. Middle narial passage, a cleft in 

 the cartilage of the snout filled with connective tissue. n, v, vn, ix, x. 

 Foramina for the exit of cranial nerves. 



forming intervertebral cartilages which were not ossified, for as we 

 have just seen this state of affairs is found in some living Urodela. 

 The haemal arches of the tail are, like the ribs, outgrowths of the 

 basiventrals, but they do not exactly correspond to the ribs, for they 

 are placed nearer the middle line. 



S. & M. 



34 



