S. W. Williston 301 



of the head of the femur, covering a little more than a third of a circle, 

 is at right angles to the long axis of the shaft, making articulation im- 

 possible, except in a strongly abducted condition. Similar evidence is 

 presented by the glenoid articulation of the humerus, demonstrating, I 

 think, the improbability of an ordinary quadrupedal position in ambula- 

 tion, as Seeley has restored some of the European forms. I am con- 

 vinced that the thigh was rotated outward, through an angle of thirty 

 or forty degrees, and was directed outwardly nearly in a coronal plane 

 at an angle of thirty or forty degrees from the mesial line. I am not 

 sure, indeed, but that the knees may have been turned at times more or 

 less backward. The condylar surface of the femur is such that the knees 

 could not have been flexed much, if any, more than a right angle. The 

 tibige might easily have been brought parallel with each other, while the 

 femora were outwardly rotated and abducted. 



This normal outward rotation of the femora is also shown in an ex- 

 cellent specimen of the hind extremities of Ornitliostoma ingens pre- 

 served in the matrix. The heads of the femora occupy their normal 

 relation to each other in connection with the remains of the pelvis, but 

 both were directed outwards with the trochanters turned inwards. I 

 may add here that in removing one of these femora for further study 

 of its shape, I was greatly surprised to find on the under surface — the 

 ventral— very vivid markings of the integument. Photographs of these 

 will be given later. I may say here that there is no direct evidence of 

 either scales or feathers, but the numerous, regularly placed patches 

 of darker material are such as might have been produced by the skin of 

 a bird where there are many feathers. Since we have hitherto been 

 entirely ignorant of the covering of the body of these animals, the dis- 

 covery is one of great interest. I am convinced that the integument was 

 not a simple smooth membrane over the body, though what it really was 

 I am not prepared to say. I expect to find further evidence, that I hope 

 will solve the question, when the remaining bones of the specimen have 

 been removed from the matrix. 



So far, then, as the evidence of the legs goes, the animal may have 

 stood erect upon its feet with the thighs rotated outward and tibiae 

 far apart. Of the clawless character of the feet in these animals there 

 can be no question. A specimen collected by me nearly ten years ago 

 has the bones all intact and in position. The feet were not in the least 

 prehensile. 



The articulation of the humerus with the coraco-scapula was nearly 

 perfectly saddle-shaped, with its axes nearly in the planes of the body, 

 t'nlike the legs, there was little or no rotation of the upper extremity. 



