54 



TRUNK VERTEBRA. 



[chap. 



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, 

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

 former case, but rather with the lower transverse processes 





Fro 21.— Anterior surface of vertebrae of Sperm Whale (Fhyseter nmcrocephalus). M 

 A eighth thoracic; b ninth thoracic; c tenth thoracic; d fifth lumbar; r rib ; 

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



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. 



The mode of ossification of the thoracic and lumbar 

 vertebrae of the Cetacea appears, so far as it has been 



