84 O. 0. Marsh—Restoration of Brontosaurus. 
Tur VERTEBRA. 
There are twenty-seven precaudal vertebrae in Brontosaurus, 
of which the first twelve bear pleurapophyses, or hatchet bones, 
united to the centra, and may hence be called true cervicals. 
Of the remaining twelve which bear free ribs, the thirteenth, 
fourteenth, and fifteenth have the surface for the articulation 
of the head of the rib on the centrum, below the neural suture. - 
All the precaudal vertebree have large cavities in the centrum, 
communicating exteriorly with the surface by means of large 
lateral foramina. This cavernous structure of the vertebre 
Post-METAPOPHYSES. 
On the last two or three cervical vertebrae of Brontosaurus, 
