176 0. C. Marsh — The gigantic Ceratqpsidw, 



(1) A rostral bone, forming a sharp, cutting beak. 



(2) The skull surmounted by massive horn- cores. 



(3) The expanded parietal crest with its marginal armature. 



(4) The teeth with two distinct roots. 



(5) The anterior cervical vertebrae coossified with each other. 



(6) The posterior dorsal vertebrae supporting, on the dia- 

 pophysis, both the head and tubercle of the rib. 



The Ceratojpsidm resemble, in various points, the Stegosauria 

 of the Jurassic, especially in the vertebrae, limbs, and feet. 

 The greatest difference is seen in the skull, but the pelvic arch, 

 also, shows a wide divergence. In the Ceratopsidw, there is 

 no marked enlargement of the spinal cavity in the sacrum, and 

 there is no post-pubis. 



The characters above given are based upon fossils which I 

 have personally investigated, including the type specimens 

 of Ceratops and Triceratops, on which, mainly, the family 

 Ceratopsidw was established. The material now at my com- 

 mand includes the remains of many individuals, among which 

 are portions of about twenty different skulls, and some of these 

 are nearly perfect. In the memoir now in preparation, I shall 

 fully describe and illustrate all the more important of these 

 specimens, and likewise discuss their relations to allied forms. 



The generic names, Agathaumas, Cratceomus, 3fo?ioclonius, 

 and one or two others, have been given to fragmentary fossils, 

 which may belong to this group, but these remains, so far as 

 made known, appear quite distinct from those here described. 



In conclusion, let me say a word as to how the discoveries 

 here recorded have been accomplished. The main credit for 

 the work justly belongs to my able assistant, Mr. J. B. Hatcher, 

 who has done so much to bring to light the ancient life of the 

 Eocky mountain region. I can only claim to have shared a 

 few of the dangers and hardships with him, but without his 

 skill and energy, little would have been accomplished. If you 

 will bear in mind that two of the skulls, represented in the 

 diagrams before you, weighed nearly two tons each, when 

 partially freed from their matrix, and ready for shipment, in a 

 deep, desert canon, fifty miles from a railway, you will 

 appreciate one of the mechanical difficulties overcome. When 

 I add that some of the most interesting discoveries were 

 made in the hunting grounds of the hostile Sioux Indians, 

 who regard such explorations with superstitious dread, you will 

 understand another phase of the problem. I might speak 

 of even greater difficulties and dangers, but the results attained 

 repay all past efforts, and I hope at no distant day to have 

 something more of interest to lay before you. 



