238 FIELD COLUMBIAN MUSEUM. 
MEASUREMENTS OF CAUDAL VERTEBR&. 
Caudal I. Caudal II. 
Heicht. Oyersall soi cc onde ot eae teat later PRRs arma BAe me 61% .59 
Ceftram lenpiit-ote cea. PAPE tale tore ye Werther AES 5 ie . 16 aS 
Depth of anterior end........ WA Ok es Be .28* ne 
Breadth of anterior enain7 7). 24-ha tm tee eee eee 33 AGE 
Breadth across transverse: processesy nors/) ie ce ee . 56* .48 
opine, height above zy gapophyses.... cal: ee eee .18 oS) 
Anteroposterior diameter. S20 ie ee a are wd i" .10 
Lateral diameter avicrest. ait areca) ce mee ene ae ee Ne a! .09 
*Dimension modified by distortion, - 
The tlia are represented by the right bone, which has lost its 
greater peduncle, but is otherwise quite well preserved, and a badly 
weathered left, which, fortunately, has the greater peduncle pre- 
served. The right bone has been modified by a distortion which has 
depressed the whole posterior half, straightened the superior border, 
distorted the acetabulum, and reduced the depth in the supra- 
acetabular region. It is figured from a lateral view without correc- 
tion, other than the restoration of the greater peduncle from a com- 
parison with that of the left. (Fig. 3, Plate LX XV.) 
The important feature of the ilium is the unusual development of 
the pre-acetabular portion. The greater peduncle is near the middle; 
the anterior half is expanded into a broad but rather thin plate, 
most of which stands anterior to the attachment of the first sacral 
rib. At the point of greatest eminence the crest is thickened for the 
attachment of the first diapophysis. The anterior border is much 
more rounded than it is in any of the other large dinosaurs. At the 
anterio-inferior angle the border is quite thick and roughened for 
muscular attachment. This roughening continues one-third of the 
way from the angle to the point of attachment for the first sacral 
diapophysis, where it disappears and the border becomes thin and 
rounded. ‘The crest continues very thin to a point over the middle 
of the acetabulum, where it again becomes stronger and rugose. 
This continues to the posterior angle, which is much thickened, and 
offers the usual broad surface for the origin of lateral caudal muscles. 
The acetabulum is distorted by the depression of its arch. It 
presents to the head of the femur a broad and rounded surface, which 
terminates at either end in the peduncles. Its superior surface takes 
the form of an arch which juts far beyond the iliac wall on the 
mesial side, and presents a concave surface for the support of the 
sacricostal yoke. The attachment for the first diapophysis is a 
triangular fossa bounded by two ridges which descend from the crest 
and converge at a point’ seven or eight inches below. From this 
