On the Osteology of Nyctosaurus. 145 



measurements of pteroid. 



mm. 

 Length 104 



Greatest width (at proximal end) 15 



Diameter of articular surface 8 



The next three metacarpals are, for the most part, wanting in this 

 specimen, a single complete one lying near the distal extremity of the 

 right wing metacarpal (PI. XLII, Fig. 6). It is a very small, splint- 

 like and slightly curved, pointed bone, measuring about twenty-four 

 millimeters in length by two in greatest width. Its resemblance to the 

 corresponding metacarpals of Pteranodon is so great that the whole 

 structure of the hand is doubtless the same in the two genera. I give 

 herewith a diagrammatic figure of these parts in. Pteranodon, based on a 



^Y^ 



Fig. 2. Metacarpals of Pteranodon ingens. 



specimen in which nearly all the bones were present and in position, 

 some of the terminal phalanges only being misplaced, and one or two of 

 the fourth finger missing. In a former paper I stated that the phalanges 

 of the hand were of two kinds, long and short. Possibly this is the case 

 in some of the smaller species, but I think not. I doubt not that the 

 small phalanges there described were from the foot, and had become dis- 

 placed and associated with the hand phalanges in the specimen described. 

 In the specimen of Pteranodon the small metacarpals seemed to lie, 

 not as they are diagrammatically figured, one above the other, but more 

 side by side. The second metacarpal is continued, as already stated by 

 Marsh, to the carpus, as a thin, thread-like bone. It was not continued 

 along the dorsal side of the bone, but seems to pass to the radial side, 

 where it belongs. From this it seems also probable that the position of 

 all three bones in life was along the radial dorsal margin of the fifth 

 metacarpal. 



Both of the wing metacarpals (PI. XLIV, Fig. 2) lie upon the dorsal 

 surface, a position in which they are seldom found. The bone is much 

 broader at the base, tapering to beyond the middle, whence the shaft 

 has nearly parallel sides. The proximal articular surface cannot be 

 made out, though there appears to be a division into two facets. The 

 condyles, as in Pteranodon, are placed obliquely, the posterior one the 

 larger. 



