hatcher: diplodocus (marsh) 39 



processes are given, column 2 greatest length of centra, column 3 diameter of centra 

 at posterior extremity, 4 height of neural spines above middle of inferior border of 

 centra in presacrals and above inferior border of posterior end in presacrals. 



Measurement of Ilium and Sacrum, No. 84. 



Greatest length of ilium 1089 mm. 42| in. 



Length of five coossified centra 765 



Height of coalesced spines 1092 



Fore and aft diameter of three coalesced spines at the summit 170 



Height of coalesced spines above superior acetabular border 970 



Distance from top of iliac crest to extremity of pubic peduncle 787 



43 



38^- 

 31 ' 



When adjusted to- each other and placed in a straight line the forty-one vertebrae 

 belonging with skeleton 84 form a series forty-three feet in length. Of this distance 

 the fourteen cervicals measure 21 ft. 4 in., the eleven dorsals 10 ft. 8 in., the sacrals 

 1 ft. 9 in., and the twelve caudals the remaining 9 ft. 3 in. Add to this combined 

 length of forty-three feet two feet for the skull and atlas and 23 ft. for the difference 

 between 9 ft., the length of the twelve anterior caudals, and 32 ft., the total length 

 of the caudal series as estimated by Osborn from their quite complete caudal series, 

 and we shall have a total length of 68 ft. for the vertebral column and skull of this 

 skeleton of Diplodocus. 



The Neural Canal. 



The neural canal is exceedingly small throughout the entire vertebral column 

 when compared with the enormous bulk of the animal. Except in the sacrals where 

 it is considerably enlarged, it nowhere has a diameter of more than two inches, 

 hardly greater than that of the neural canal of a modern Rhinoceros. The small 

 neural canal, together with the small skull and very small brain cavity of the latter 

 are indicative of an extremely primitive nervous system and show that Diplodocus 

 was a creature of but little mental or physical activity, sluggish in its movements, 

 and but ill adapted to successfully compete with its contemporaries in a struggle for 

 existence amid changing environments, especially when such changes were in any 

 manner unfavorable to its existence. 



The Sternum. — Associated with skeleton No. 84 were two somewhat irregularly 

 shaped bones closely resembling in shape and size those figured and described by 

 Marsh as the sternals of Brontosaurus. Marsh does not describe the sternals of 

 Diplodocus except to say that "they are large and resemble those of Brontosaurus 

 excelsus.'^ These bones are somewhat ovate in outline, with the narrower extremity 

 much thickened and rugose, while at the opposite end they expand into broad, thin 



