No. 535] THE SAUROPODOUS DINOSAURS 403 



the U. S. National Museum measures 510 mm. across the 

 bone just below the rough proximal end. On the fibular 

 border the rugose surface that represents the great 

 trochanter runs down on the bone a distance of 390 mm. 

 At this point there is a decided angle in the border on the 

 bone. A rough surface just like this in position and ex- 

 tent is found on the femur of the Grocodile. 



This being settled, we may turn our attention to what 

 Marsh and Hatcher called the great trochanter, the 

 outer half, or nearly as much, of the rough proximal end 

 of the femur. Those who do not believe that this formed 

 a part of the head of the bone and was not inserted in the 

 acetabulum ought to explain what it represents. 



As regards the distal end of the femur of Diplodocus, 

 I do not see in what way it is essentially different from 

 that of the lizard. Dr. Matthew says that in the latter 

 the distal articulation for the tibia and the fibula are on 

 the back of the femur, not on its end. As I see the femur 

 of Diplodocus and that of the lizard, both have a broad 

 articular surface on the end; and this surface is con- 

 tinued around on the ventral side of the bone, being 

 there divided into two parts by the intercondylar fossa. 

 It must not be supposed that I see no differences among 

 the femora of the diplodocus, the crocodile and the liz- 

 ard; but these are much nearer one another than tbat 

 the diplodocus is to the femur of the elephant. 



Dr. Holland has made the objection that in articula- 

 ting the leg bones of Diplodocus so that there might be a 

 right angle between the femur and the tibia there would 

 be no surface against which the end of the femur might 

 articulate. However, the same condition would exist in 

 the flexed knee of the horse or of man were it not for 

 the patella. In the flexed knee of the lizard and of the 

 crocodile the end of the bone is covered by the tendon of 

 the extensor muscle and the ligaments; and certainly 

 the same was true in the sauropods. On account of the 

 deep body of Diplodocus it would not probably often 

 happen that the angle between the femur and the tibia 



