44 



PEOCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 69 



prominent to correspond Avith the progressive increase of the pos- 

 teroexternal angle on the anterior caudals. The centrum is longer 

 and broader than that of the first lumbar and is constricted behind 

 the neural arches. The right transverse process and neural spine 

 have been restored. 



Measurements of the lumbar vertebrae {in millimeters) 



Greatest depth (vertically) of verte- 

 bra (tip of neural spine to inferior 

 face of centrum) 



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 from inferior carina on cen- 

 trum to tip of left transverse pro- 

 cess 



Maximum width of extremity of left 

 transverse process 



Distance between tip of right post- 

 zygapophysis and tip of right pre- 

 zygapophysis 



Minimum anteroposterior diameter 

 of neurapophysis 



Anteroposterior length of neural 

 spine in a horizontal line immedi- 

 ately above the zygapophyses 



Vertical height of neural spine (dis- 

 tance between superior margin of 

 neural canal and tip of spine) 



Minimum anteroposterior diameter 

 of neural spine 



Eth 



27 



lOth 



X 



X 



31 

 26 



X 



2 36.5 



61 



X 



' Estimated. 



Anterior epiphysis missing. 



CAUDAL VERTEBRAE 



The caudal series is likewise incomplete and the j^osition (pi. 1, 

 fig. 1 ) of those that are preserved shoAvs that they were torn apart be- 

 fore they were completely covered by sediments. Behind the pos- 

 terior lumbar are the first, second, and third caudals, and the anterior 

 epiphysis of the fourth. Two others which appear to be the sixth 

 and seventh caudals are isolated from the rest. Behind them there 

 appears to be another hiatus, for there are five consecutive vertebrae 

 from near the middle of the series which appear to be the tenth, 

 eleventh, twelfth, thirteenth, and fourteenth caudals. In addition to 

 the above, there is one small terminal caudal. 



In enumerating the differences between the caudal series of this 

 fossil porpoise and that of Sotalia guianensis, the relative antero- 

 posterior diameters of the neural arches and the position of the dorsal 

 orifice of the lateral vertebr arterial canal should not be overlooked. 



