the Skeleton of Diplodocus Gamegiei. 363 



nature of this bone that the writer draws some of his chief conclusions. 

 The first point to which we must direct attention is that the head 

 of the femur is very poorly developed, as in the crocodile. Indeed, 

 the femur as a whole is very crocodilian — a fact which some 

 writers seem inclined to ignore. This imperfect head offers con- 

 firmation of the writer's view with regard to the arrangement of the 

 hind-limbs. For it seems rather obvious that, if these limbs were 

 intended to be upright and for walking in the manner of an elephant 

 or other large mammal, then we should find this head of the femur 

 much more fully developed — that is, rounder, larger, and more distinct 

 altogether. As it is we see a mere bulging out on one side of the 

 proximal end. How different this to the mammalian femur ! But 

 to come back to the Dinosauria, even the huge Stegosaurus has 

 a more developed head to the femur. And there is good reason to 

 conclude that this creature used its hind-limbs for walking rather 

 than for crawling, and that they were set at a slight angle to the 

 long axis of the body, as in birds. Again, 2'riceratops (von Zittel, 

 Palceontology, ii, p. 243, Engl, ed.) confirms our view ; for its femur 

 shows quite a well-formed head, and this Dinosaur was much 

 inclined to a quadrupedal gait. The writer ventures to think that 

 the femur of Diplodocus shows a distinct advance upon that seen in 

 Varanus or Grocodilus. We see the head asserting as it were a kind 

 of individuality. It projects distinctly from the shaft, though only 

 to a slight extent. We might almost be allowed to believe that 

 here Nature was dimly groping after the. more perfect types that we 

 see in the Mammalia. We can well believe that this was one 

 reason which led Hatcher and others to place the hind-limb nearly 

 vertical. It is of course most essential that we should know the 

 true shape of this bone as well as others. Now the femur we are 

 dealing with is not the actual bone itself, but a reconstruction. The 

 only way to be sure in these matters is to go to the actual fossil 

 bones and see and judge for ourselves what their shapes may be. 

 For this purpose one must go to the Fossil Reptile Gallery of our 

 Natui-al History Museum. There we see bones and casts of bones of 

 the Sauropoda. There is a femur of Diplodocus. It is a good deal 

 crushed, especially at one end. One can compare it with the 

 corresponding bone of Brontosaurus, Cetiosaurus, and the colossal 

 Atlantosaurus. The writer was greatly interested to find that the 

 bone is distinctly curved (see Fig. 4b). It has a double curvature. 

 This is a very important fact, the meaning of which must be carefully 

 borne in mind when one is attempting to make a restoration of 

 Diplodocus. It brings us back to the crocodile, and reminds us that 

 we are far away from the mammalian type. To place such a bone in 

 a nearly vertical plane and so imply that Diplodocus was a kind of 

 saurian elephant must be wrong from a mechanical point of view, as 

 well as anatomically ! In birds, and in mammals, the head of the femur 

 is well developed ; and the acetabulum is so shaped as to conform to 

 this neat spherical head, forming an admirable ball-and-socket joint, 

 a device well-known to the engineer, and well exhibited in man and 

 in birds. But among reptiles this feature is usually absent, being 

 only known among the Chelonia. The femur of the tortoise (or 



