30 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. r,3. 



The prezygapophysial facets are wider apart and are more divergent 

 than tlie postzygapophysial facets (pi. 14, fig. 2). The metapophyses 

 project beyond the epiphyses of the centrum throughout the series 

 while in the case of the postzygapophyses, with the exception of the 

 first four dorsals, such is not the case. The metapophyses also 

 rapidly increase in size from the seventh to the tenth dorsals and 

 beginning with the seventh dorsal project obliquely upward. 



The second and third dorsals are very similar in appearance to 

 the first. The most apparent differences are the increase in distal 

 width of the neural spines and the shifting of the articular facet 

 for tubercle of rib to a more lateral position on the transverse process. 



The fourth (pi. 13, fig. 3), fifth, and sixth dorsals possess deep 

 neural spines and their anterior and posterior margins are slightly 

 curved. The transverse processes are well developed and project 

 forward in the first six dorsals. Anteriorly they arise high up on 

 the neural arch and when followed back gradually shift their 

 position on the vertebrae until on the tenth dorsal they project 

 from the middle of the centrum. On the tenth dorsal, the trans- 

 verse process and its articular facet for the tuberculum of rib are 

 directed backward. The external face of the transverse process is 

 deeply excavated, furnishing a broad concave articulating surface 

 for the accommodation of the tuberculum of the corresponding rib. 

 On either side of the centrum of the first six dorsals, just anterior 

 to the posterior epiphysis, is a circular digital depression for the 

 accommodation of the capitulum of the following rib. On the 

 eighth dorsal (pi. 13, fig. 4) the articular facet for the capitulum lies 

 just below that for the tuberculum. A corresponding facet is not 

 present on the last two dorsals for the ribs articulate solely with the 

 transverse processes. 



The facets for the tubercles of the ribs increase in width from the 

 first to seventh dorsals, and gradually shift in position until on the 

 seventh dorsal the facet is behind the level of the anterior epiphysis 

 of centrum. On the anterior dorsals the facet for the tubercle 

 projects in front of the anterior epiphysis. The lateral transverse 

 process which bears the articular facet for tubercle of rib and which 

 internally is continuous with metapophysis increases in size from 

 the first to seventh dorsal. The transverse process drops down to 

 the level of the centrum on the eighth dorsal. The neural canal 

 is roughly semicircular in outline inferiorly, but above, owing to 

 the depression of the neurapophyses, it is pointed, as shown in 

 plate 13, figure 2. The anterior articulating surfaces of the centra 

 are convex, while the posterior faces are slightly concave. 



