32 
THE SAUROPOD DINOSAUR BAROSAURUS MARSH. 
Figure 5. — Chevron ca. XVI. A, rear, B, right lateral aspect. One- 
fourth natural size, he, haemal canal ; m, muscle area ; a, alveolus. 
depression seems to be in no way homologous with the perforation mentioned in chev- 
ron IX. 
There is on either side a distinct muscle area (Text Fig. 5 B, m) on the proximal 
portion of the chevron, bounded by a pronounced horizontal ridge. This is not apparent 
on either of the two chevrons which have been described. The chevron of Diplodocus 
longus type (Yale Mus. No. 1920), which is shown on Plate VI, Fig. 8, represents but 
one half of the bone under consideration, as the cleavage into two elements is here 
complete. There is, however, a facet at the posterior end only for contact with the 
other element of the pair (see also Text Fig. 6). 
Measurements of Chevron ca. XVI 
Barosaitrus 
lent its 
mm. 
Perpendicular length 120 
Width of base 93 
Horizontal length as preserved 181. 5 
Haemal canal, height 14 
width 25 
Alveolus, antero-posterior diameter 20 
transverse diameter 5 
" depth 18 
Figure 6. — Chevrons of Diplodocus longus, inferior aspect, after Marsh. 
One-fourth natural size. Compare Figure 4. 
