MESOZOIC VERTEBRATA. 
3 () 
the other angle is expanded into a shai-p, convex crest, or ala. A section 
of this extremity is diamond-shaped, with one of the lateral planes pro¬ 
duced into this crest, while the corresponding border of the opposite side 
drops down, being represented by a mere convexity of the surface, which 
continues to the crest. The surface of the extremity is irregular. The 
section of the shaft is a broad oval, becoming subcircular near the proximal 
extremity. The latter is enlarged in both directions. It is a rectangle in 
outline, a little extended in the plane of the limb, with one of the angles 
cut off from the corresponding angle to the middle of one side. The long 
side thus left is slightly convex, and ends in an angle.' The side subtended 
by this angle is slightly concave, and is approximated to. the other bone. 
The opposite side is slightly emarginate near the middle. Its surface is 
very slightly convex, and is irregularly grooved and pitted. 
The more slender of the two bones is but little and about equally 
expanded at the opposite extremities. The distal end would have an ovoid 
section, but for the fact that it is obliquely truncate at the extremity next 
to the other bone. It is convex in the antero-posterior direction and plane 
in the transverse; its surface is grooved and pitted. The side next to the 
other bone is flat or slightly concave at the distal end, and, though thicker 
than the external border, becomes rounded at the middle of the shaft, and 
is again flattened at the proximal extremity. The external border is dis- 
tally produced into an obtuse angle; lower down, the shaft has a thin, 
angular border. The proximal end has less antero-posterior diameter than 
the distal, and is subtriangular in outline ; the apex being acute and ex¬ 
ternal. The surface is flat, and is strongly marked with deep grooves. 
The other surfaces of the limb-bones are smooth, except a few weak ridges 
near the distal ends of the two distal bones. 
Measurements. 
Length of the part of the scapula preserved... 
Width at the middle.. . 
Thickness at the middle.... 
Thickness at the proximal angle .... 
Total length ot humerus.. 
. 1 1 ( ‘R the head. 
Diameter of the proximal end [ ,„,,e..„sities 
M. 
0. C80 
0. 270 
0. 048 
0.117 
0. 765 
0. 080 
0. 225 
