THE POSE AND LOCOMOTION OF DIPLODOCUS. 25 



regarding the approach of another, which is swimming. In the far 

 distance is a fourth specimen lying stretched out at full length on the 

 bank. 



In the paper published by Mr. Ballou, referred to on page 15, 

 there is a figure which represents a group of four individuals of 

 Amphicaiias latus, a dinosaur closely related to Brontosaurus and 

 attaining a length of from 60 to 80 feet. These animals are shown 

 as walking about on the bottom of a river, feeding on the vegetation 

 there and rising on their hind legs to reach the air. The idea here 

 suggested is adopted by Professor Osbom^® as correct. Mr. Knight, 

 under Professor Osborn's direction, has made a restoration of Bronto- 

 saurus*^ in which the same idea regarding the habits of the sauropods 

 is inculcated. In this restoration a number of individuals, otherwise 

 invisible, are sticking their heads out of the water. The ability of 

 any large animal to walk thus submerged must depend on its having 

 a massive skeleton, as have the hippopotamus and the manatee. In 

 Diplodocus, on the contrary, almost every conceivable device has been 

 employed to reduce the weight of the skeleton. The great vertebrae 

 contain large and small internal cavities, while externally the processes 

 are canned into thin plates and buttresses and the centra are deeply 

 excavated on each side. Moreover, as has been shown by Hatcherj^"* 

 the limb bones are hollow. It would seem to have been hardly more 

 possible for Diplodocus to walk about immersed in water than it 

 would be for a man to do the same. Even if the reptile could have 

 remained sunken, any pressure by the feet in the effort to walk would 

 have sent it to the surface. 



After the text and the drawings of this paper had been completed 

 the writer received the Scientific American of November 6, 1909, in 

 which is printed a popular article on the attitude of Diplodocus. In 

 this article mention is made of a paper on this subject recently pub- 

 lished by Dr. Gustav Tornier of Berlin, a paper not previously seen 

 by the present writer. Unfortunately too, he has not seen the original 

 papers of Messrs. Drevermann and Boule. No numbers of the 

 Umschau, of Frankfort, for the present year are accessible. 



"Bull. Amer. Mus. Nat. Hist., x, p. 220. 



•» Amer. Mus. Jour., V. p. 68. 



*' Mem. Carnegie Mus., i, p. 53, fig. 23. 



