150 FIELD COLUMBIAN MusgEuM—GEOLOoGy, VOL. II. 
uniting them in a complete basin, with the necessary curvatures, it 
transpires that the opening of the pelvis had a diameter of about seven- 
eighths of an inch, while the outlet could have measured but a trifle more 
than half an inch. 
Femur. Pl. XLIII, Figs. 4, 5. Both femora are preserved, separated 
by a short distance from the pelvis. The neck is directed upward and at 
a slight angle inward; it is cylindrical, the head only a little dilated and 
with its convexity only a little oblique to the axis of the bone; that is, the 
plane of the rim is nearly, but not quite, rectangular to the axis of the 
shaft. The trochanter stands a little to the outer side of the middle axis 
of the bone. From its upper angle a ridged process runs backward for a 
short distance, to the inner side of which, a little below the free, upper 
concave margin of bone, there is a small pneumatic opening. On the 
outer side, the margin of the shaft is convex for a short distance, and is 
then concave throughout to the extremity. On the inner side above, the 
margin is:.correspondingly concave; below this to the condyle it is con- 
vex. ‘The upper part of the bone was evidently, in life, nearly cylindrical; 
below it seems to have been wider and somewhat flattened. Near the 
middle behind, beginning a little above the condylar surface, there is a 
narrow, elongated, longitudinal ridge for the attachment of a muscle. 
The distal articular surface cannot be clearly made out in the crushed 
specimens. The bone had in life, apparently, a marked anterior curva- 
ture, as in Preranodon. 
MEASUREMENTS OF FEMUR. 
Lengtho2 sit oo ese ssh eel een Bg ee ee re ee ee ee 81 
Diameter-of neck 222 -y 202i bese 53 eb nae oo ee 6 
Diameter of shaft, upper third:-.-.----- 22h. 2 8 
Diameter through condyles as, crushed_-_-__232.2._.__-. 9-2) 2. 3 13 
Femur of Pteranodon ingens Marsh, Pl. XLIII, Figs. 1-3. The con- 
vexity of the head is regular, covering nearly half of a circle transversely, 
probably a little less in the conjugate diameter, the surface thus forming 
an oval or ovate figure, the plane of whose base is nearly at right angles 
to the long diameter of the bone. ‘The convex surface is sharply limited 
from the neck. The neck is cylindrical, rather stout, and is directed 
nearly vertically downward. ‘The rounded and moderately prominent 
trochanter is placed over the middle of the shaft, descending into the 
concavity at the side of the neck, and externally separated from the 
margin of the bone. The shaft is nearly of equal width throughout; 
doubtless in life it was nearly cylindrical, with a strong anterior curvature, 
and a flattening in the popliteal region. The sharp margin of the inner 
condyle encompasses nearly half a circle. The outer condyle, though 
