76 DIXOCERATA. 



The Fifth Vkrteijra. (Woodcuts Si» und 90, lielow.) 



In the fifth cervical vertebra of Dinoceras mirahile (number 1255), 

 the centrum is nearly round. The articular faces are distinctly concave, 

 especially the posterior one. The neural canal is sub-triang-nlar in 

 transverse section, 'i^'he arch to protect the lateral foramen is more 

 depressed than in the preceding- vertel)ra. Tlie more important features 

 of this vertebra are shown in figm-e 8'J, below. 



FiGUBE 89 — Fifth tLr\ It il %Viteljia of l'iH"Caras );i'r(i5i7e, Marsh (Xo. 12."i.'j|; front view. 

 Figure 90. — The same ^eitcbia, side view 



/. lateral foramen; nc. neural canal; z. anterior zygaiioplivsis ; z'. posterior zygapophysis. 

 Both fignres are one-fourth natural ei/.e. 



The principal measurements of the fifth A'ertel)ra in this specimen of 

 Dinoceras mirahile are tlie following: 



Measurements of Fifth Ceroical Vertebra. [THnoccras mirahile. No. 12.55.) 



m. 



Length of floor of neural canal, ('52 



Lens^th of centrum, along under surface, _ - . — -"'SS 



Transverse diameter of neural canal, ■, -O-^C 



Vertical diameter <>f neural canal, , ' -^35 



Transverse diameter of anterior epiphysis, -OVO 



Vertical diameter of anterior epiphysis, '. . - .""^^ 



Transverse diameter of posterior epiphysis, . 089 



Vertical diameter of posterior epiphysis, . — -080 



Antero-posterior extent of zygapophyses, - 08.3 



Transverse diameter, across pre-zygapophyse.?, . - -1-0 



Transverse diameter, across post-zygapophyses, — .1-3 



Diameter of lateral foramen (aiiproximate), - - .020 



