HOLLAND: THE OSTEOLOGY OF DIPLODOCUS MARSH 255 
graph of the specimens as they are arranged for exhibition in the Gallery of Paleon- 
tology at South Kensington. Similar series of very slender rod-like caudal verte- 
bree have been recently found in connection with specimens of Brontosaurus. 
That the enormously elongated, and at its extremity highly attenuated tail of these 
great reptiles was liable to injury, is shown by the caudal vertebree of Diplodocus 
in the collections of the Carnegie Museum, as well as by the caudal vertebree of Cetio- 
saurus leedsi preserved in the British Museum. In specimen No. 84 (Carnegie Mu- 
seum Catalogue of Vertebrate Fossils) caudals 2 and 8 are codssified, as has been 
already pointed out by Mr. Hatcher in his Memoir, and this codssification appears 
to be pathological rather than normal. In specimen No. 94 caudals Nos. 20 and 21 
are firmly codssified, as are also caudals Nos. 24 and 25. The codssified caudals 
Nos. 20 and 21 were described and figured as doubtfully Nos. 17 and 18 by Mr. 
Hatcher on page 36 of his Memoir. Maturer and more careful study has proved 
that they should be given the position which they now hold in the restored skele- 
ton. ‘The codssification in the case of both of these instances is evidently due to 
traumatic causes. An examination of the photograph of the rod-like caudals of 
Cetiosaurus leedsi (Fig. 24) shows plainly that several of these bones have sustained 
injury, as might easily happen by being crushed under the feet of other individuals, 
or when used possibly for purposes of defense in giving blows to the right and to 
the left. 
Plate X XIX. represents the caudals from No. 37 to No. 73 inclusive as these 
were found in serial order by Mr. Utterback. 
THE CHEVRONS. 
In the restoration of the skeleton represented by Mr. Hatcher in the Memoirs 
of the Carnegie Museum, Volume I., Plate XIII., the anterior chevrons are some- 
what exaggerated in length. The chevrons had not been put into place at the time 
of Mr. Hatcher’s death, and it fell to the writer to supervise this part of the work. 
The original drawing for Mr. Hatcher’s plate was made by Mr. R. Weber, who 
based his drawings of the cheyrons upon material which had not been experi- 
mentally assigned to positions in the skeleton. Mr. Hatcher’s death compelled the 
writer to take up the work. The anterior chevrons used in making the reproduc- 
tion were those found with our specimen No. 84, and these are shorter than those 
represented in the drawings made for Mr. Hatcher by Mr. Weber and accord, there- 
fore, more nearly in proportion with physical requirements. Many of the chevrons 
after the first six are reproductions of those found and described by Professor Osborn 
in his paper on Diplodocus published in Volume I. of the American Museum of 
