On the Osteology of Nyctosaurus. ' 141 



he calls doubtfully a pneumatic foramen. Whether the part is an acro- 

 mion process of the scapula, or possibly a vestigial clavicle, must be left 

 for future research. 



The coracoid has a flattened shaft, oval in cross-section near its middle, 

 and flattened at either extremity. The sternal articular surface is convex 

 in its greater diameter, gently concave in the opposite direction. Near 

 the outer extremity of the shaft, on the inferior border, there is a strong 

 process, gradually arising f-rom the shaft but with a deep concavity be- 

 tween it and the articular rim. A small sesamoid ossicle was found 

 lying near it. The shaft at its middle is narrowed and smooth; it seems 

 to lack the strong muscular rugosity on the external part which occurs in 

 the Pteranodon coracoid; the process on the outer inferior border is also 

 larger than in Pteranodon. It will be observed also in the figure that 

 the glenoid articular surface does not extend to the inferior margin of the 

 coracoid, resembling in this respect somewhat the European forms of this 

 bone. The scapula of course differs markedly from that of Pteranodon 

 in the non-articular distal end. 



measurements of coraco-scapula. 



mm. 



Extent of coraco-sternal articulation 10 



Least width of shaft, below middle of coracoid _ 7 



Length of coracoid .; 55 



Dorso-ventral diameter of glenoid surface -- 19 



Length of scapula 49 



Least width of shaft of scapula 14 



Width at distal extremity 16 



Humerus. PI. XLII, Fig. 7. The humeri both lie with the inner 

 side uppermost. The proximal articular surface is distinctly saddle- 

 shaped, the convexity directed from behind forward and inward. The 

 curve of the concavity is greater than that of the convexity in the speci- 

 men. The ulnar or median process is very stout, reaching as high 

 as the articular surface. It is broad above, with apparently two faces 

 for muscular attachment, separated by a narrow, free space. Its rounded 

 distal border sinks into the surface of the shaft at about its middle 

 third. The deltoid, radial, or lateral process is very large. It is directed 

 forward and a little downward, its lower margin uniting with the shaft 

 at about the middle third. Both upper and lower borders are deeply 

 concave, the upper one the longer. Its distal extremity is expanded, 

 and has an evenly convex border from above downward. Near the 

 upper end of this border, on the inner side, there is a small, oval, 

 oblique surface, looking inward, for muscular attachment; and, begin- 

 ning near the middle of the upper border, there is a slender, but well- 



