THE HORNED DINOSAURS — GILMORE. 387 



American Museum of Natural History, New York City. This is the most per- 

 fect skeleton of a horned dinosaur that has yet been discovered. About ^natural 

 size. After Brown. 



Plate 3. 



Upper: Horn cores of Triceratops alticornis (Marsh), found in the Denver 

 formation, Upper Cretaceous, near Denver, Colorado, in 1887. Cat. No. 4739, 

 U. S. N. M. About & natural size. 



Lower: Longitudinal section through a skull of Triceratops to show the very 

 small size of the brain case, as indicated by the white area near the center of 

 the picture. Cat. No. 5740, U. S. N. M. 



Plate 4. 



Upper : Impressions of the skin overlying the hip bone and the upper portion 

 of the articulated thigh bone (femur) of the right side. The lower part of the 

 femur lies exposed to view at the left of the rule. The bone to be observed on 

 the extreme left of the picture is the ischium, one of the pelvic bones. Photo- 

 graph reproduced through the courtesy of the Geological Survey of Canada. 

 Photo by Charles M. Sternberg. 



Lower: Impressions of the skin overlying the right femur of a specimen of 

 Monoclonius in the American Museum of Natural History, New York City. 

 After Brown. 



Both of the above specimens are from the Belly River formation, Upper 

 Cretaceous, as exposed along the Red Deer River, Alberta, Canada. A region 

 now famous for the remarkable preservation of the dinosaurian specimens 

 found there. 



Plate 5. 



Upper : Skull of a Triceratops shown partially chiseled out of a sandstone 

 cliff in eastern Wyoming. Photograph by Charles H. Sternberg. 



Lower: Skull of Triceratops, excavated and swathed in plaster-of-Paris 

 bandages and now ready for boxing. Collected on Hell Creek, Montana, by Mr. 

 Barnum Brown. Photograph reproduced through the courtesy of the American 

 Museum of Natural History. 



Plate 6. 



A comparison of the skull of a horned dinosaur, Styracosaurus (left), and 

 the skull of a horned toad (right). Both viewed from above. The Styracosaurus 

 skull measures 6 feet, the horned toad skull 1 inch in length. Photograph of 

 Styracosaurus after Lambe. 



Plate 7. 



Fig. 1.— Skull of Triceratops prorsus Marsh. Cat. No. 2100 U. S. N. M. About 

 xV natural size. 



Fig. 2. — Head of Chameleo owenii from South Africa. A living lizard that 

 has a fairly perfect crest or frill and three horns, placed precisely as in Tricera- 

 tops. Adapted from Metcalf. After Lull. 



Fig. 3. — Skull of Monoclonius, one of the earliest known forms of the horned 

 dinosauria, showing the large openings or fenestra in the frill, the small horns 

 above the eyes, and the large forwardly curved horn on the nose. About ■£$ 

 natural size. After Lambe. 



Plate 8. 



Mounted skeletons of the largest (Triceratops) and the smallest (Brachy- 

 ceratops) known members of the horned dinosauria, shown as now exhibited 

 in the United States National Museum. About fa natural size. 



