208 Frof. 0. C. Marsh— The Wings of Pterodactyks. 



having in life a spread of wings from fifteen to twenty feet. They 

 were also destitute of teeth, and belong to the order Pteranodontia. 

 Probably their great size induced special modifications of the 

 scapular arch, which is here far more complicated than in any other 

 members of the group. 



In the Jurassic Pterodactyles, the scapula is usually bird-like in 

 general form and proportions, the upper or distal extremity being- 

 free and compressed. This is the case in the specimen here described. 

 The scapula and coracoid may be coossified, as in the present fossil, 

 or remain more or less separate. No clavicles have yet been found. 

 The sternum hei'e shows no distinct facets for sternal ribs. 



In the Cretaceous genus Pteranodon, and probably also in some of 

 the other gigantic forms from deposits of this age, the scapula and 

 coracoid were not only solidly united, but the pectoral arch was 

 further strengthened, (1) by the ankylosis of several vertebree, and 

 (2) by the robust scajoulee articulating on opposite sides of the 

 common neural spine of these vertebras. This is virtually a repeti- 

 tion of the pelvic arch, on a much larger scale. The sternum also 

 is massive, and shows well marked facets for the sternal ribs. This 

 peculiar method of strengthening the scapular arch has not been 

 observed in any other vertebrates. 



The Wing Bones. 



The three principal bones of the arm (humerus, radius, and ulna) 

 present such similar characters in all Pterodactyles that they need 

 not be considered here in detail. It is important, however, to bear 

 in mind that the ulna, although but little larger than the radius, 

 contributes the greater share of direct support to the enormously 

 developed wing finger, which is on the outer or ulnar side of the 

 hand. As this position has been a question of discussion among 

 anatomists, it may be well to state, that the writer bases his opinion 

 upon this point on the results of an examination of the best pre- 

 served specimens in European museums, as well as nearly all known 

 in this country. The latter specimens settle the question beyond 

 doubt. 



The views expressed by anatomists in regard to the bones of the 

 wrist and hand of Pterodactyles are almost as various as the 

 specimens investigated. Some of the restorations of these parts that 

 have been published from time to time, and repeated in text books, 

 have done much to propagate errors, and little to clear away the 

 serious difficulties in the case. The main facts in regard to the 

 carpus now known may be briefly stated as follows : 



In all Pterodactyles, there are two principal carpal bones, placed 

 one above the other. These sometimes show indications of being 

 composite, but their constituent parts have not been satisfactorily 

 determined. On the inner side of the wrist, articulating with the 

 distal carpal, there is a smaller bone which has been called the 

 " lateral carpal." In addition to these three bones, some American 

 Pterodactyles have on the inner side three ossicles, which may be 

 sesamoid bones. Two of these have been seen in a few Jurassic 



