124 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



are attenuated toward extremity. A small elongated vertebrarterial 

 canal perforates the base of the right transverse process. The en- 

 largement of these upper transverse processes and the absence of the 

 lower transverse processes also distinguish this cervical from the sixth 

 cervical. In development these upper transverse processes resemble 

 somewhat those on the seventh cervical of Inia, which, however, has a 

 long slender neural spine (58 mm.) and large lateral vertebrarterial 

 canals. The pedicles of the neural arch are wider than those of the 

 sixth cervical. The prezygapophysial facets slope less steeply from 

 outer to inner margins than on the sixth cervical and the postzygapo- 

 physial facets are unusually elongated (24.5 mm.). The neural spine 

 is reduced to a low crest. 



Measukements of cervical vertebrae (in millimeters) 



Atlas C.5 C.6 C.7 



Greatest vertical diameter of articular sur- ! 



face for condyle (right) 49. , 



Greatest transverse diameter of articular 



surface for condyle (right) 32. 5 



Least anteroposterior diameter of dorsal 



face of neural arch 25. 8 



Least anteroposterior diameter of pedicle 



of neural arch 

 Greatest height (vertically) of vertebra (tip 



of neural spine to ventral face of centrum) 84. 

 Anteroposterior diameter of centrum 

 Distance across vertebra between tips of ■ 



transverse processes (parapophyses) 113.5 94.5 84.+ 111. S 



Distance across vertebra betv^een tips of 



upper transverse processes (diapophyses) 71. 



Distance between tip of prezygapophysis 



and tip of postzygapophysis 27. 7 28. 3 34. S 



Transverse diameter of neural (spinal) canal ' 



anteriorly 35. 26. 29. 31. 0. 



Maximum height of neural (spinal) canal 



anteriorly 37. 5 17. 5 17. 5 19. (^ 



Greatest distance across vertebra between 



outside margins of anterior articular 



facets 88. ' 



Greatest distance across vetebra between 



outside margins of posterior articular , 



facets 82. x 



DORSAL VERTEBRAE :^ 



With the exception of the neural spines and the extremities of the 

 prezygapophyses, all four dorsal vertebrae (USNM 15985) associated, 

 with the skull and mandibles are otherwise essentially complete.^ 



