HO, 635] THE SAUBOJPODOUS DINOSAURS 



399 



the knee-joint, when the leg is flexed, as shown in his 

 Fig. 11, in which ease, as he states, the tibia and the 

 fibula come into contact with the condyles of the femur 

 at two points not larger than as many sixpences. But 

 we must suppose that the Biphxlocus did sometimes lie 

 down, and in so doing did bend its legs as much as Dr. 

 Holland has represented, or more. Whoever has ob- 

 served the effort required by a horse in regaining a 

 standing posture can imagine the strain that would come 

 on those femoral condyles and lower leg bones when the 

 reptile endeavored to get on his feet again ; but we can 

 hardly suppose that the bones and cartilages of the 

 knees were crushed every time the animal arose from its 

 slumbers. Dr. Holland appears not to appreciate the 

 fact that all these articular surfaces were invested with 

 abundant cartilage. 



Dr. Holland's Figs. 15 and 16 illustrate the embarrass- 

 ments encountered by him in his efforts to adapt the 

 bones of the fore leg to the positions that they have in 

 the lizard. He would have had fewer difficulties had he 

 not been laboring under the misapprehension that the 

 upper end of the radius articulated with the inner 

 condyle of the humerus instead of the outer. Such a 

 transposition of the radius and ulna would present 

 something unique in anatomy and, in the case of the 

 sauropods, would be wholly unnecessary. 



From the compressed form of the body of Diplodocus 

 f>r. Holland has derived an argument against the propo- 

 sition that the reptile had a creeping mode of locomotion. 

 Dr. Abel also formulates the generalization that among 

 the reptiles which in locomotion do not lift the belly and 



the thorax is transversely oval. It is true that most 

 creeping animals have the body depressed, but they vary 

 greatly with respect to the amount of depression. On 

 the other hand, there are lizards which have the body 

 strongly compressed and which nevertheless progress 

 as do other lizards. A species of the genus Gonyocepha- 



