ON THE OSTEOLOGY OF NYCTOSAURUS. 143 
deeply concave surface on the inner side. Just in front of this, near the 
middle of the bone, transversely, there is a pneumatic foramen on the 
flexor side. The inner side of the bone, at this extremity is expanded 
into a thin; convex process. ‘The articulation at the distal extremity can- 
not be made out, as it is largely concealed by the carpals. ‘The shaft is 
nearly straight, curved forward gently at the distal extremity. 
MEASUREMENTS. 
mm. 
RE Es a ee ee ara Cpe 144 
EMC TITALC XULOIIUC Yr Sy oe es oh a's a Soe ee oak woe 44 
RIT ee ety ee pe tee ee 24 
Radius. Pl. XLI, Fig. 2, Pl. I. The radius is a more slender and 
slightly shorter bone than the ulna. On the left side it lies partly con- 
cealed beneath the ulna and there would seem to have been no pronation 
of the bone. The bone is more slender than the radius, somewhat concave 
along its inner or upper border as it lies in relation with the ulna; nearly 
straight as it lies compressed from above downward. ‘The bone is more 
expanded distally than proximally. The proximal articular surface is 
rounded and concave. Lying near the roughened distal surface shown 
in the figure there was a small sesamoid bone. 
MEASUREMENTS OF RADIUS. 
mm. 
ES ae Ne nn ee Hn en 9 8 =- 140 
IE eerie itd) oe oe ek se tae een nae 2 See 18 
Ee eV lee ie ee re ee a ee oe os te 24 
eae ie x 11), igs. 2,,cc,.3, Pl. XLIV, Fig. 8... The two chief 
carpals of the left wrist are in relation with each other and the wing meta- 
carpal, and but slightly displaced from the forearm bones. On the right 
side they are separated, and the proximal one is partly concealed beneath 
the ischium, the distal one having its proximal surface obliquely exposed. 
In the figure (Pl. XLIV, Fig. 10), the one shown obliquely is that of the 
other carpus figured. The wing metacarpal of the left side (Pl. XLIV, Fig. 
2), lying articulated with the distal carpal, has the under side uppermost, 
from which it would appear that the view given is of the anterior side of 
the carpus. The proximal carpal is much the larger, extending on the © 
under side either to articulate with the metacarpal, or nearly so. A sub- 
angular space is left between the two bones on the radial side, for the 
articulation of the lateral carpal or metacarpal of the first digit. This 
latter bone, of the right side, is shown in Pl. XLII, Fig. 3. It is a small, 
elongate bone, with an articular emargination on one side, which I had 
supposed was for the pteroid. I give, also, a good figure of this bone 
of Pteranodon, copied from Cope (Cretaceous Vertebrata, Plate VII, 
