ABT. 26 



REMAINS OF FOSSIL PORPOISES KELLOGG 



29 



arches are not as long anteroposteriorly as those of the eleventh 

 dorsal and are characterized by curved anterior and posterior mar- 

 gins. The neural canals of these lumbars are narrow, high, and 

 roughly triangular in outline. In cross section the centra of all 

 three lumbars are roughly pentagonal in outline. The transverse 

 processes or parapophyses are thin, relatively narrow, long, and in- 

 cline downward. The neural spines appear to rake backward to a 

 more noticeable degree than those of the posterior dorsals. The 

 prezygapophysial facets are situated on the internal faces of the 

 obliquely directed laminae which arise from the anterior margins of 

 the neural arches. The postzygapophysial facets are small and are 

 situated on the lateral faces of the neural spine at the posteroinferior 

 angle. There is a well-defined ventral carina on the eighth and tenth 

 lumbars. 



Measurements of lumbar vertebrae (in millvmeters) 



Sixth 



Eighth 



Tenth 



Greatest depth (vertically) of vertebra (tip of neural spine to inferior 

 face of centrum).. 



Greatest depth of neural canal anteriorly... 



Greatest breadth of neural canal posteriorly 



Height of anterior face of centrum 



Breadth of anterior face of centrum.. 



Height of posterior face of centrum 



Breadth of posterior face of centrum 



Length of centrum 



Distance across vertebra between tips of parapophyses 



Distance across vertebra between tips of prezygapophyses 



Distance across vertebra between outside margins of postzygapophysial 

 facets. 



Distance between tip of right postzygapophysis and tip of right prezy- 



gapophysis 



Minimum length of neurapophysis 



Anteroposterior length of neural spine in a horizontal line immediately 



above the zygapophyses 



Anteroposterior diameter of left parapophysis at extremity 



Vertical height of neural spine (distance between superior margin of 

 spinal canal and tip of spine) 



180.2 

 33.8 

 18.7 

 52.5+ 

 56.8+ 

 52.3+ 

 55.3+ 



> 66 



193.3 

 27.7+ 



6.2 



84 

 40 



44.5 

 23.5 



95.2 



1 Epiphysis missing. 



s Estimate. 



CAUDAL VERTEBRAE 



It may seem unusual that these five caudal vertebrae are so widely 

 separated from each other in the column, but on the basis of Abel's 

 figure they will have to be assigned somewhere near the following 

 positions. The epiphyses of three of these caudals are nearly circu- 

 lar, even though the centra are irregularly pentagonal. Although 

 the transverse processes of the fifth caudal (pi. 12, fig. 1) are broken 

 off near the base, it is evident that these processes were somewhat 

 shorter than those of the tenth lumbar. The lateral faces of the 

 centrum (pi. 11, fig. 1) both above and beloAV these processes are con- 

 cave. The neural arches are high and long anteroposteriorly. The 

 neural spine is short and its posterior margin curves forAvard. The 

 neural canal is very narrow in proportion to its height. Large 

 protruding postero-inferior facets for the chevrons (pi. 13, fig. 1) 



