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THE AMERICAN NATURALIST [Vol. XLIV 



is far more perpendicular than is the case in the picture 

 before you, and they carry the tail even higher. Ordi- 

 narily these lacertilians crawl, trailing the tail behind 

 them, but when alarmed they rise upon their hind feet 

 and throw the tail upward, moving along with great 

 speed. I do not advocate such a position for the tail 

 of Diplodocus, but, simply because it is long, to declare 

 therefore that it must have necessarily trailed with its 

 whole length upon the ground, does not appear to me 

 to be reasonable. Animals with tails relatively quite 

 as long, and even longer, are known to-day to hold them 

 elevated, and there was proportionately as much mus- 

 cular power, as shown by the muscular attachments, in 

 the tail of Diplodocus, as there is in the tail of a Crota- 

 phytus or a CMamydosaurus. To declare as Mr. Hay 

 does, that these animals must have moved as crocodiles 

 and could not by any possibility have raised themselves 

 from the ground, does not appear to me to be logical. In 

 fact, those of us who have hunted alligators know that in 

 life even alligators raise themselves high upon their 

 legs when running, and get away like a dog at a sort 

 of a trot. 



Tornier indulges in a lengthy criticism of the pose 

 given to the feet in recent reproductions of the Diplodocus 

 and demands that they shall be placed in a plantigrade 

 position. He thus takes issue with Mr. Hatcher and 

 with others who have carefully examined the subject. 

 Professor Abel, of Vienna, in criticizing Dr. Hay's 

 article, has very aptly pointed out that the manner in 

 which the metacarpals articulate in the pes and manus 

 indicates a more or less digitigrade position. Those of 

 us who are familiar with the feet of the sauropod dino- 

 saurs know very well that in their structure, as indicated 

 by the facets of both the proximal and distal end, there 

 is strong evidence that they were not plantigrade in the 

 sense in which the feet of existing reptiles are planti- 

 grade. I throw upon the screen a diagram showing the 

 proximal ends of the metacarpal and metarsal elements 

 (Fig. 19). They arrange themselves in a semicircle 



