THE WING-FINGER OF PTERODACTYLS 



7°3 



bursal sacks and synovial joints, 

 as a tendon or sesamoid bone is 

 quite possible and even probable, 

 but that the bone finally acquired 

 another function, at least in the 

 most highly developed forms, 

 would seem to be very prob- 

 able. The function that has 

 generally been ascribed to it is 

 that of a " Spannknochen " or 

 tensor of the patagial membrane 

 in front of the elbow. Under 

 the assumed relations of the 

 membrane to the front of the 

 arm I have protested against this 

 theory, since the fact is that 

 there could have been little or 

 no membrane in this region to 

 be rendered tense, provided the 

 membrane terminated, as is 

 usually assumed, at the shoulder. 

 Under the assumption that it 

 really served as a "Spann- 

 knochen" I have suggested in 

 an earlier paper that the mem- 

 brane continued beyond the 

 shoulder along the side of the 

 neck to the skull. 



In the accompanying restora- 

 tion, Mr. Herrick E. Wilson, of 

 the University of Chicago, after 

 careful study, has embodied 

 these views, based upon my 

 skeletal restoration of Nycto- 

 saurus. I believe that this 

 restoration comes nearer to the 

 real appearance of a pterodactyl 



That the pteroid bone originated 



Fig. 4. — Right front leg of Varano- 

 saurus Broili, a theromorph reptile from 

 the Permian of Texas. Seven-tenths 

 natural size. 



