10 OLIVER P. HAY 



practically the ultimate, or mammalian stage. The writer believes 

 that it had attained only the first station in the journey. 



A study of the femora of the sauropods shows that the proximal 

 end varies somewhat in shape. Usually it is more or less truncated 

 or it is slightly concave toward the fibular side and convex toward the 

 tibial side. Figure 4 represents in outline a side view of the proximal 

 half of the bone, as represented by Hatcher. As already stated, the 



FIG. 4 OUTLINE OF SIDE VIEW OF PROXIMAL END OF FEMUR OF DIPLODOCUS. 



x*. 



proximal border is very rough, as shown by figure (Fig. 5) also taken 

 from Hatcher. Undoubtedly this was covered by a thick layer of 

 cartilage. Cope (Amer. Naturalist, xii, 1878, p. 84) says that if the 

 layer of cartilage were ossified it would be an epiphysis, like that of 

 the mammals. Figure 6 presents the same outline as does figure 4, 



FIG. 5 PROXIMAL END OF FEMUR OF DIPLODOCUS. h, THE*SO-CALLED HEAD 



but to it there has been added a dotted line which is intended to indi- 

 cate the writer's view of the form of the upper end of the femur 

 when the cap of cartilage was present. The stage of development 

 reached by the animal was that at which a femoral head was being 

 developed on the tibial side of the bone and the fibular border was 

 being freed from the articular cup. Although the whole proximal 

 end may, in some genera, have been too broad to enter the cavity 



