146 Field Columbian Museum — Geology, Vol. II. 



MEASUKEMENTS. 



mm. 



Length 224 



Width at proximal end 18, 23 



Width of shaft at middle u, 12 



First phalange of wing finger. PI. XLIV, Fig. 1. The first phalange, as 

 usual, lies upon the side in both wings. As in Pteranodon, it is the long- 

 est bone of the body. Its under margin is concave throughout, the con- 

 cavity greater near each end. The proximal expanded extremity has a 

 deep articular concavity, extending through an arc of about one-third of 

 a circle, with its radius directed at an angle about 45 ° with the long axis. 

 The upper, olecranon-like projection has a marked emargination of the 

 border above, between which and the proximal end the convexity is 

 greater, with the corresponding deeper concavity of the under border. 



There are two articular facets, separated by a median ridge, which 

 fits into the trochlear depression of the metacarpal. The posterior sur- 

 face extends throughout the whole length of the arc, while that on the 

 anterior side reaches but little more than one half of the distance, and 

 its upper part is narrower than is the other surface. The pneumatic 

 foramen is on the anterior side, just beyond the end of the articular sur- 

 face. The dorsal border of the bone is gently and evenly convex from 

 a little beyond the proximal extremity, and the width on the distal three- 

 fifths is nearly uniform. The distal extremity of the bone is curved 

 downward; the articular surface in life was doubtless a vertical oval. 



measurements. 



mm. 

 Length 283 



Greatest width at proximal end 27 



Chord of proximal articulation 17 



Width of shaft, proximal third 14 



Width of shaft, distal third--- 14 



Width distal extremity 18 



Thickness of shaft at middle as compressed 1.7 



The second wing phalange (PI. XLIV, Fig. 5) lies in position in the 

 right wing, but is somewhat displaced in the left. It is much smaller 

 and more slender than the first phalange. Its proximal border is nearly 

 straight and transverse to the axis of the shaft; it ib much broader than the 

 shaft. The under border of the bone is gently concave throughout, 

 except on the proximal part, where the concavity is deeper. The upper 

 border, gently concave at the proximal end, is nearly straight thence to 

 near the extremity. The distal extremity is quite like that of the first 

 phalange, though smaller. 



