MORPHOLOGY OF BAROSAURUS LENTUS. 2 7 
Caudal XV (PL V, Figs. 4, 5). — This bone shows but little distinction from caudal 
XIII, and is about as perfect in its degree of preservation. 
Measurements of Caudal XV 
Barosaurus 
lentils 
mm. 
Length over all 34° 
Height over all 4 2 o 
Centrum, length 245 
" anterior face, height . . . 217 
" " " width 247 
" posterior face, height 200 
" " " width 240 
Pleuroccele, length 135 
" height 35 
Neural canal, height (anterior end) 31.5 
" width " " 42 
Neural spine, width of summit 84.4 
" " length " " 112.5 
Caudal XVI. — Centrum only preserved. The longitudinal cavity beneath the cen- 
trum is becoming more pronounced, while the curvature of the anterior face is less, its 
depth being to the width as 1 : 15. The pleuroccele is still distinct and has the form of 
quite a deep conical depression. The posterior face of the centrum is somewhat concave. 
Measurements of Caudal XVI 
Barosaurus 
lentus, 
mm. 
Centrum, length 255 
" anterior face, height 205 
" " " width 220 
" posterior face, height 195 
" width 235 
Pleuroccele, length 150 
Caudal XVII (PI. V, Fig. 6). — This is a splendidly preserved bone except for the 
diapophyses. Of the centrum, neither face is much curved, but the anterior aspect is 
slightly more concave. The pleuroccele is still well developed and the inferior concavity 
of the centrum is becoming pronounced. Well developed chevron facets are present, of 
which the posterior are still the more prominent. 
Both anterior and posterior zygapophyses overhang the centrum, the former to a 
greater extent than the latter. The neural arch is low, the spine, however, rising well 
over the after end of the centrum, and jutting about 50 mm. beyond it posteriorly. 
The summit of the spine differs decidedly from that of caudal XV, as it is not so highly 
rugose, and the curve of the summit is semicylindrical, with the long axis antero- 
posterior. The summit slopes downward gently toward the rear. The insertions for 
the longitudinal interspinose ligaments on front and rear face are still well developed 
and rugose. Laminae from the prezygapophyses run almost horizontally backward, 
gradually rising to reinforce the spine. 
Caudal XVIII seems to be missing from the series, the discrepancy in proportions 
between the one just described and the next preserved being too great to admit of 
their being contiguous. 
