MORPHOLOGY OF BAROSAURUS LENTUS. 1 9 
Measurements of Dorsal V 
Barosaurus Diplodocus 
lentus carnegiei Ratios 
mm. mm. 
Height over all 840! 845* 0.99 
Height of neural arch to cleft of spine 473 
Height at postzygapophysis 514 500 1.03 
Centrum, length ca. 310 245* 1.26 
anterior face, height 200$ 280* 0.71 
" width 320 278* 1. 15 
posterior face, height 255 250* 1.02 
" width 320 295* 1.08 
" circumference 940 844§ 1.11 
Pleuroccele, length 60 
" . height ca. 80 
Neural canal, height 43 
" " width 50 
Width across pedicels 200 
Average ratios : Barosaurus lentus and Diplodocus carnegiei 1.04 
* Peterson's measurements. 
t Estimated. 
$ Error from crushing and lack of preservation considerable, as opposing face of dorsal IV = 240. 
§ Calculated. 
Dorsal VI (PI. VI, Fig. 3). — This vertebra seems to be represented by the 
summit of the neural spine only, with no identifiable trace of the remainder of the 
bone in the collection. The bone fragment is very heavy and rugose, and may well 
have formed the common anchorage for the paired muscles and tendons of the bifid 
spines in front. This from its appearance is assumed to be the first unpaired spine. In 
Brontosaurus, the first uncleft spine which is broad and heavy like the one under con- 
sideration is borne by the sixth dorsal, in Diplodocus carnegiei by the seventh, and 
even there and in the eighth and ninth the summit is slightly cleft. In D. longus at 
the American Museum of Natural History the spine of dorsal VI is the last bifid one, 
and, as in the Pittsburgh specimen, the succeeding ones are slightly notched and not 
straight-topped as in Barosaurus. In Brachiosaurus none of the dorsals shows a bifid 
spine. In this feature, therefore, the resemblance is with Brontosaurus rather than 
with either Diplodocus or Brachiosaurus. 
Breadth of the neural summit, 190 mm.; its antero-posterior diameter, 92 mm. 
The development of the heavily rugose pre- and postspinal laminae gives this bone 
fragment a distinct tripartite character, as though it formed not alone the origin of the 
great paired muscles of the neck, but short and powerful median tendons connecting 
with the spinal lamina of the preceding and succeeding vertebra. 
Dorsal VII {Vertebra 0) . — This bone, while complete as to its dorsal spine, lacks 
the diapophyses and is otherwise seriously crushed and mutilated. The spine has 
suffered a curious torsion, but was asymmetrical even in life, as the prezygapophysial 
lamina on the left side is very much narrower than on the right; their respective 
widths being 3 mm. and 22.3 mm. 
Anterior aspect. — The anterior face of the centrum is badly crushed, so that its 
original width may not be ascertained. The neural arch has diminished in width, being 
but 115 mm. across the pedicels as compared with 230 mm. for dorsal V. The pre- 
