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THE AMERICAN NATURALIST [Vol. XLII 



The beds of the streams were continually shifting, and 

 there existed numerous abandoned channels that were 

 filled with stagnant water. An animal that lived in such 

 a region would be compelled to adapt itself to a more or 

 less aquatic life, and this adaptation would be reflected 

 to a greater or less extent in the structure of the animal. 

 Marsh had concluded from the position of the external 

 nares of Diplodocus that it was addicted in some measure 

 to an aquatic existence. The feet too are of rather 

 peculiar structure, the inner toes being strongly clawed, 

 the outer toes greatly reduced ; but the meaning of this is 

 differently interpreted. 



The Food of Diplodocus 

 The particular sort of food eaten by the species of Dip- 

 lodocus is unknown, but nobody doubts that it was vege- 

 table. The teeth were pencil-like in form and they were 

 entirely confined to the front of the jaws. By general 

 consent, they could have been employed only for prehen- 

 sion of food, not at all for its mastication. Hatcher sug- 

 gested that the teeth might have been useful in detaching 

 from the bottoms and shores the tender and succulent 

 aquatic and semi-aquatic plants that must have grown 

 there in abundance. Osborn 3 says that "the food prob- 

 ably consisted of some very large and nutritious species 

 of water plant. The anterior claws may have been used 

 in uprooting such plants. . . . The plants may have been 

 drawn down the throat in large quantities without masti- 

 cation." In a restoration of Diplodocus by Mr. Charles 

 W. Knight 4 the animal is represented as standing on its 

 hind legs and preparing to bite off the terminal bud of a 

 towering cycad. Holland 5 thinks that the teeth were 

 better adapted for raking and tearing off from the rocks 

 soft masses of clinging algae than for securing any other 

 forms of vegetable food now represented in the waters of 

 the world. 



3 Mem. Amer. Mus. Nat. Hist., I, p. 214. 



American, XCVI, 1907, p. 485. 



