60 



AIJATOMY OF VERTEBRATES. 



main with those in the Python. In Istiurus the cervical hypa- 

 popliyses are compressed, distinct, and articulated to the inter- 

 sjjace between their own vertebra and the one in advance. The 

 caudal vertebraj are remarkable for the great length of their 

 neural spines. 



In the Chameleon the ribs commence at the fourth vertebra, 

 and those of the sixth are articulated by semiossified cartilages to 

 the sternum, as are the tlu^ee following pairs ; in the next eight 

 or ten jiairs the long and slender cartilages meet and unite to- 

 gether at their extremities. There are two lumbar and three 

 sacral vertebra3 ; the tail is long and prehensile. In the 

 Iguana tuberculata twenty-one vertebra;, commencing with the 

 fifth, support free ribs, and those of the ninth first join the 

 sternum. 



§ 23. Vertebral column of Chelonia. — This column is most ex- 



51 



SkeU'tnii iir J^miis Eiiropd-a. xxxviil. 



traordinary in those RepfiUa to wliich, in llie manifold modifica- 

 tions of tlie organic framework, has been given a portable abode, 

 in compensation for inferior powers of locomotion and the want 

 of dcfcnsl^•e weapons. 



