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THE AMERICAN NATURALIST [Vol. XL V 



toes having a reduced number of phalanges, seem to fur- 

 nish almost positive proof that their possessors had for 

 many generations been accustomed to travel on solid 

 ground. It is probable that their resort to the water had 

 not endured long enough yet to affect to any great de- 

 gree their organization, except as to size. 



Dr. Matthew believes that at some stage the ancestors 

 of the sauropods were bipedal and that later they became 

 secondarily quadrupedal. He grants that the indica- 

 tions of former bipedalism in this group are less appar- 

 ent than in the quadrupedal Predentata. It is easy to 

 agree with the latter opinion. As to the hinder limbs, 

 we ought to expect that bipedal locomotion would have 

 led to the development of smooth, well-finished articular 

 surfaces and of a trochanter major standing out as a 

 distinct process near the upper end of the femur. Why, 

 on the resumption of quadrupedal locomotion, should 

 these acquisitions have disappeared as if they had never 

 existed? This has not happened even in the walruses, 

 seals, porpoises and manatees, which forsaking the 

 land, have betaken themselves to the water. The inevi- 

 table result, if not the prerequisite, of bipedalism is a con- 

 siderable reduction in the size of the fore legs and vari- 

 ous transformations of the hands. But the fore limbs of 

 Diplodocas and of Brontosaurus show no reduction in 

 size. Are we to suppose too that while the fore legs 

 were held from contact with the ground and were prob- 

 ably employed for other purposes than locomotion, they 

 continued to progress in digitigrady! Those fore feet 

 look as if they had been walked on fully as much as the 

 hinder feet. 



From a photograph of the fore foot of a Diplodocus 

 in the American Museum of Natural History Dr. v. 

 Huene concludes that this foot was exaxonic. It would 

 be interesting to learn more about this foot, especially 

 whether or not the bones were found in their natural 

 relations. The foot differs from that of some other 

 sauropods, certainly. With the ulna and radius before 



