488 O. C. Marsh—On Dinosaurian Reptiles. 
Bearing these facts in mind, the diagram representing the 
restored fore and hind limbs of the diminutive Hallopus 
(figures 4-5) shows first of all the true Dinosaurian pelvis, 
with the pubic bone taking part in the open acetabulum, and 
forming an important and distinctive element of the pelvic 
arch. The delicate posterior limb and foot, evidently adapted 
i) 
— 
> 
FicgurE 8.— Pelvis of Morosaurus lentus, Marsh; seen from the left. One-eighth 
natural size. 
a, acetabular opening; other letters as in figure 7. 
mainly for leaping, as the generic name suggests, are quite 
unique among the /eptilia, but the tarsus, especially the 
caleaneum, recalls strongly the same region in the orders 
already passed in review. 
