6o 



THORACIC AND LUMBAR VERTEBRAE. [CHAP. 



processes. In two or three vertebrae the two co-exist (Fig. 

 21, B and c), resembling the upper and lower transverse pro- 

 cesses of the neck, and sometimes even meeting at their 

 extremities so as to enclose a canal. The lumbar transverse 

 processes in this case therefore are not serially homologous 

 with the transverse processes of the anterior thoracic region, 



FIG. 21. Anterior surface of vertebrae of Sperm Whale (Physeter macrocef>hahts), jV 

 A eighth thoracic ; B ninth thoracic; c tenth thoracic; D fifth lumbar; rrib; 

 m metapophysis ; t upper transverse process ; t' lower transverse process. 



and with the upper transverse processes of the neck, as in the 

 former case, but rather with the lower transverse processes 

 of that region ; and yet tried by every other test, the special 

 homology of the transverse processes of the lumbar vertebrae 

 of a Dolphin (Fig 20, D t) and a Sperm Whale (Fig. 21, D /) 

 is perfectly evident. 



