NO. 1426. SKELETON OF TRICERATOPS PRORSUS—GILMORE. 435 



It may be of interest to mention here that Prof. O. C. Marsh used 

 this skeleton (No, 4842), supplemented by other remains now pre- 

 served in the collections of the Yale Museum, for the basis of his 

 restoration of Trlcerafoj^s jj7'o?'sus, published as Plate LXXI in the 

 Dinosaurs of North America." Plates LXIV-LXVIII in the same 

 work were also largel}'^ reproductions of parts of this same individual. 



A comparison of the a))Ove restoration b}" Marsh with the mounted 

 skeleton (see Plates I and II) shows several ditfercnces in points of 

 structure, due chiefly to the better understanding of these extinct 

 forms. The most striking dissimilarity is in the shortening of the 

 trunk by a reduction of the number of presacral vertebrae Marsh's 

 error was due to an overestimate of the length of this region, a mis- 

 take also made in his restoration of Brontosaurus (Apatasaurus), as 

 has been shown by Riggs.* Mr. Hatcher determined, from a well- 

 preserved vetebral column in the Yale Museum, the number of pre- 

 sacrals as twenty-one, this ))eing six less than a.scribed to the animal 

 by Marsh. 



At the time of his death Mr. Hatcher had about completed a mono- 

 graph on the Ceratopsia for the United States Geological Survey. 

 This report was begun some j^ears before by the late Professor 

 Marsh, but after his untimely demise it fell to the lot of the collector 

 of this material to finish it.'^ In studying all of the specimens pre- 

 served in the museums of this country. Hatcher was able to make 

 several corrections in the structure, of this animal, as originally figured 

 by Marsh. These discoveries, as far as known, have been embodied 

 in the present mount, though it must be understood there are many 

 points in the structure yet to be determined. 



The skeleton was mounted by the present writer, being very ably 

 assisted by Mr. Norman Boss, but the author alone must be held 

 responsible for whatever anatomical inaccuracies may be detected in 

 the reconstruction. 



« Included in the Sixteenth Annual Report of the U. S. Geological Survey. 

 & Science, n. s., XVII, March 6, 1903. 



<"Mr. Hatcher' .s manuscript has recently been placed in the hands of Dr. R. S. 

 Lull, of Amherst College, who will attend to its tinal preparation for publication. 



