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THE AMEBIC AN NATURALIST [Vol. XL V 



would be less than a right angle. When the leg was ex- 

 tended forward it would be nearly straight and again 

 straight when directed backward. Also, the body would 

 be lifted somewhat. It is an erroneous idea, held ap- 

 parently by both Dr. Matthew and Dr. v. Huene, that in 

 walking the crocodiles, lizards and turtles do not lift the 

 body from the ground. Probably all do so; even the 

 gigantic Galapagos tortoises carry their bodies free 

 from the ground. 



Inasmuch as the arrangement of the bones of the fore 

 leg has been brought into this discussion, I shall make a 

 few remarks on the subject. Few of the figures of the 

 humerus give a correct notion of its form. Those pub- 

 lished by Osborn and Granger 7 show well the characters 

 of the bone, seen from the front only, in three genera of 

 sauropods. A humerus in the U. S. National Museum, 

 supposed to be that of Diplodocus, has the proximal 

 border broad and convex and very rough, showing that 

 it was covered by cartilage and doubtless formed a con- 

 tinuous articular surface. This surface played in the 

 glenoid fossa or notch of the shoulder girdle. About 

 the middle of this convex surface the bone is much thicker 

 than at the ends and the thickening is on the dorsal face 

 of the hone. This thickened portion quite certainly corre- 

 sponds to a rounded elevation seen on the upper surface 

 of the proximal end of the humerus of the crocodile, and 

 this in its turn is probably homologous with the more nar- 

 rowly limited head of the humerus in mammals. In the 

 crocodile this elevation fits well into a depression in the 

 scapula, in the roof of the glenoid fossa. When, however, 

 the leg is brought well forward the elevation slips out of 

 the glenoid notch and a part of the head farther forward 

 takes its place and rapports the weight. I believe that 

 the same movements took place in Diplodocus. 



Now, in the restoration of Diplodocus in Pittsburgh 

 and in that of Brontosaurus in New York, the humerus 

 is placed in the glenoid notch in an approximately verti- 



