i8 95 . THE HABITS OF ARCHMOPTERYX. 183 



add that their joints are at different levels, showing that each finger 

 could be flexed independently of the rest, and therefore that they 

 were free and not bound together. I also showed that they did not 

 support the quills, but were free from the wing except at their carpal 

 ends. If they were bound together in the wing they would be 

 inflexible, inasmuch as the joints of each digit are at different levels 

 from those of the other digits. 



I have already referred to the long, lizard-like body of the 

 animal, and to the absence of that shifting backwards of the heavy 

 abdominal viscera which is seen in such bipeds as birds, squirrels, 

 kangaroos, dinosaurs, etc. ; but I do not wish now to rely upon mere 

 analogy. The form of the body is so clearly shown that it is obvious 

 that its centre of gravity would be in front, not only of the aceta- 

 bulum, but of the knee. If the animal walked, or even stood, on two 

 feet at all, it would have had to stand either bolt upright or with its 

 dorsal surface directed slightly downwards. Whether the tail would 

 then be on the ground (as in a kangaroo) or in the air (as in a 

 squirrel) is open to doubt, for we do not know enough about the 

 flexibility of its proximal portion to be able to say with certainty 

 whether it could or could not be bent up over the animal's back. 

 The long, heavy neck and the great weight of the head, which was 

 supported by an elastic ligament, as shown by the curvature of the 

 neck in the fossil (as in Compsognathus and the pterodactyles), add 

 greatly to the force of this argument. A duck has to walk with its 

 body tipped up almost on end, in spite of the great shifting of the 

 heavy organs of the abdomen backwards between the legs. There is 

 no room for doubt that in Archvoptevyx the centre of gravity would be 

 much further forward, not only on account of the heavy head and 

 neck, but also on account of the solidity of the wing-bones, as shown 

 by the absence of pneumatic foramina. Let any who doubt the 

 justice of this argument compare the pelvis as seen in Plate II. (which 

 the authorities of the British Museum have kindly allowed to be pre- 

 pared in illustration of this article) with the pelvis of, say, a pigeon 

 or a dinosaur, or any other animal whatever capable of walking on 

 two limbs in any but an erect position. The small size of the 

 cnemial crests, moreover, forbids us to believe that the hind-limbs 

 alone were able to bear the weight of the body when the knee was 

 bent. 



This bird was not only not a biped, but it did not walk on the 

 ground at all. It would have been as helpless on the ground as a bat 

 or even a sloth. The great length of the hind-limbs and shortness of 

 the fore-limbs, at any rate when these latter were so flexed as to keep 

 the feathers off the ground ; the position of the shoulder joint, and 

 especially of the articular surface of the humerus : these render the 

 animal unfit for such a habit as even quadrupedal locomotion on the 

 ground. The perfect state of the wing-quills at their tips shows that 

 they were not brought habitually into contact with the ground, and I 



