1016 



SCIENCE, 



[N. S. Vol. XIV. No. 365. 



mine most of the more important points regard- 

 ing the structure of the manus in this genus of 

 the Sauropoda. 



The entire limb and foot were taken up in 

 two sections, in one of which was the humerus, 

 while the other contained the radius, ulna, and 

 such portions of the manus as were preserved, 

 consisting of the supposed scapholunar, the 

 complete series of metacarpals, the five prox- 

 imal phalanges, and the ungual of the first 

 digit. All these elements when found, except 

 the scapholunar, lay in approximately their 

 normal positions, with reference to each other, 

 and thanks to the skill and care of Mr. Gil- 

 more, they were so taken up and packed that 

 their original positions had not been disturbed 

 when the limb and foot were unpacked in the 

 laboratory. 



The radius, ulna and manus have already 

 been partially freed from the matrix by Mr. 

 Gilmore, and throw considerable light upon the 

 structure of the latter. 



The limb when found lay with the palmar 

 side up. The proximal end of the radius lay 

 in the radial groove on the anterior surface of 

 the ulna, these bones still articulating with the 

 distal end of the humerus. Lying between 

 and upon the palmar side, near the distal end 

 of the radius and ulna, was a large flat bone 

 presenting on one side a gentle but regularly 

 convex surface, and on the other two flat, sub- 

 equal surfaces separated by a low ridge. This 

 bone I have interpreted as the scapholunar, and 

 it seems to be the only carpal element retained 

 in the Brontosaur manus. 



Metacarpals!. , II. , III. , IV. , V. were in regular 

 order at the distal extremity of the radius and 

 ulna, though the first and fifth were closely ap- 

 plied to the external lateral surfaces of the dis- 

 tal ends of the radius and ulna, indicating that 

 in life they articulated directly with these 

 bones, perhaps through the intermedium of 

 heavy cartilaginous pads, while the three me- 

 dian metacarpals were a little more removed in 

 order to accommodate the scapholunar men- 

 tioned above. 



The proximal phalanges of all the digits were 

 present and nearly in their normal positions 

 with relation to their respective metacarpals. 

 That of digit I, was in contact with its meta- 



carpal, but shifted from its normal position so 

 that its external lateral surface was opposed to 

 the distal end of the metacarpal, with its proxi- 

 mal articular surface turned inward toward the 

 median axis of the foot, and the distal outward. 

 The proximal phalanx of digit II. was in posi- 

 tion at the extremity of metacarpal II., but 

 very much flexed, so that its longitudinal axis 

 lay almost at right angles to that of metacarpal 

 II. It is much the larger and stronger of the 

 series of proximal phalanges, and has the dis- 

 tal articular surface deeply grooved for the 

 keel of the second phalanx. The first phalanx 

 of digit III. is much smaller than that of the 

 second, and presents distally a small, but well- 

 formed and slightly grooved, surface for the ar- 

 ticulation of the succeeding phalanx. It (the 

 first) was found in its proper position at the ex- 

 tremity of metacarpal III., and there was on 

 the palmar side, interposed between it and 

 that bone, a small rounded sesamoid. The 

 proximal phalanx of the fourth digit was in 

 position articulated with metacarpal IV. It is 

 the smallest of the series and presents distally 

 an ill-defined articular surface. That of digit 

 V. lay at the extremity of its metacarpal, but 

 with its external lateral surface opposed to the 

 distal end of the latter. This phalanx is 

 slightly larger than the corresponding one of 

 digit IV., but its distal extremity scarcely 

 shows any trace of an articular surface for a 

 succeeding phalanx. These were the only 

 phalanges found with this foot except the un- 

 gual of the first digit, which lay in its normal 

 position with reference to that of the first 

 phalanx as the latter has been described above, 

 except that it was turned on its side and had 

 been moved slightly backward, and lay with its 

 articular surface abutting against the external 

 border of the distal articular surface of the first 

 phalanx and the external lateral surface of 

 metacarpal I. 



There was a slight vertical displacement in 

 the carpal region, so that the distal ends of the 

 I'adius and ulna were a little lower than the 

 metacarpals. Metacarpals I. and V. lay in 

 such position with reference to II., III. and IV. 

 as to indicate that the proximal ends of these 

 bones were arranged in the arc of a circle, and 

 not horizontally. 



