10 PROCEEDINGS OF THE NATIONAL MUSEUM vol.81 



directed ischia gives plenty of room for the extrusion of the egg, a 

 question raised by the late Dr. S. W. Williston upon viewing the 

 rapidly drooping tail of D. carnegii for the first time. 



The National Museum skeleton as restored has a greatest length 

 between j)erpendiculars of 70 feet 2 inches, and in front of the hips 

 the tops of the spinous processes of the vertebrae are 12 feet 5 inches 

 above the ground. The head in the pose adopted is 14 feet 6 inches 

 high, but it is clearly apparent that in life it could have been elevated 

 still higher. 



The skeleton of D. carnegii is said to be 84l^ feet in length (prob- 

 ably measured over the curve of the backbone) and 14^ feet high at 

 the hips. I am at a loss to explain the difference in height between 

 the two skeletons, especially since the individual limb bones of the two 

 specimens have practically the same linear dimensions. The differ- 

 ence in length may be accounted for by the slightly greater length of 

 the individual vertebrae of D. carnegii and by the omission in the 

 present skeleton of four caudal vertebrae as mentioned elsewhere, 



NOTES ON THE DETAILED SKELETAL ANATOMY OF DIPLODOCUS 



Since the skeletal parts of Diplodocus have been described in great 

 detail by Marsh, Osborn, Hatcher, and Holland, it is now only 

 necessary to call attention to certain anatomical details displayed 

 for the first time by the specimen here described. 



Dorsal vertebrae. — The complete dorsal series of 10 vertebrae 

 was found in articulated sequence with the sacrum completely inter- 

 locked by their zygapophyses. This specimen thus positively con- 

 firms Hatcher's serial determination of the dorsals in Z>. carnegii^ 

 some of which were originally found displaced. Comparison of 

 the dorsal vertebrae of the present specimen with the illustrations 

 and descriptions ^^ of these bones of D. carnegii shows them to be 

 in accord in all important particulars, any differences being con- 

 fined chiefly to the position and direction of the various buttressing 

 laminae; but since no two vertebrae in the series are alike, and since 

 great dissimilarities often exist on opposite sides of the same verte- 

 bra, the differences noted between the dorsals of these two specimens 

 are not considered of much import. 



Viewed antero-posteriorly the spines of the vertebrae of the pos- 

 terior half of the column are relatively wider than in D. cai^negii^ 

 on account of a widening of the lateral laminae. The tall simple 

 spines of the posterior dorsals are succeeded anteriorly by emargin- 

 ate spines at the apex that become progressively cleft deeper and 

 deeper until in the anterior dorsals there are two distinct parallel 



" Mem. Carnegie Mus., Tol. 1, no. 1, 1901. 



