ILLUSTRATIONS. 



Page. 



Plate I. Restoration of Triceratops; Trachodon in the distance Frontispiece. 



II. Comparative views of crests. . . 202 



III . Comparative views of squamosal bones 204 



IV. Comparative views of nasal horn cores 206 



V. Comparative views of supraorbital horn cores 208 



VI. Lower jaw of Triceratops prorsus Marsh 210 



VII. Dorsal vertebra of Triceratops prorsus 212 



VIII. Posterior dorsal vertebra of Triceratops prorsus 214 



IX. Sacrum of Triceratops prorsus, dorsal aspect 216 



X. Sacrum of Trica'atops prorsus, ventral aspect 218 



XI. Right humerus of Triceratops prorsus 220 



XII. Right humerus of Triceratops prorsus 222 



XIII. Left ulna of Triceratops prorsus 224 



XIV. Left femur of Triceratops prorsus 226 



XV. Left femur of Triceratops prorsus 228 



XVI. Tibia and astragalus of Triceratops prorsus 230 



XVII. Metacarpals, metatarsals, and terminal phalanx of Triceratops prorsus and T. horridus Marsh 232 



XVIII. Nasal horn core of Ceratops; supraorbital horn core of Ceratops canadensis Lambe 234 



XIX. Lower jaw and teeth of Ceratops canadensis 236 



XX. Scapula and coracoid of ? Monoclonius dawsoni Lambe; predentary bone of ? Monoclonius dawsoni . 238 



XXI . Parietals of Ceratops belli Lambe 240 



XXII. Superior portion of occipital, parietal, and frontal segments of skull of Stcgoceras Lambe 242 



XXIII. Squamosal and parietal bar of Ceratops canadensis Lambe 244 



XXIV. Parietal crest and nasal horn core of Centrosaurus apertus Lambe 246 



XXV. Dorsal vertebra and sacrum of Agathaumas sylvestris Cope 248 



XXVI. Skull of Triceratops horridus Marsh 250 



XXVII. Skull of Triceratops serratus Marsh, side view 252 



XXVIII. Skull of Triceratops serratus, top view 254 



XXIX. Skull of Trica'atops serratus, oblique view 256 



XXX. Skull of Triceratops fprorsus Marsh, side view. 258 



XXXI. Skull of Triceratops fprorsus, front view 260 



XXXII. Skull of Triceratops prorsus, front view 262 



XXXIII. Skull of Triceratops prorsus, rear view 264 



XXXIV. Skull of Triceratops prorsus, side view 266 



XXXV. Skull of Triceratops prorsus, top view '. 268 



XXXVI. Skull of Triceratops prorsus, palatal view 270 



XXXVII. Skull referred to Triceratops sulcatus Marsh 272 



XXXVIII. Skull of Triceratops calicornis Marsh, side view 274 



XXXIX. Skull of Triceratops calicornis, top view 276 



XL. Vertebrse of Triceratops calicornis and T. brevicornus 278 



XLI. Skull of Triceratops brevicornus Hatcher, side view 280 



XLII. Skull of Triceratops brevicornus, palatal view 282 



XLIII. Skull of Triceratops elatus Marsh, side view 284 



XLIV. Skull of Trica'atops flabellatus Marsh, side view 286 



XLV. Skull of Triceratops flabellatus, top view 288 



XLVI. Skull of Triceratops flabellatus, palatal view 290 



XLVII. Skull of Diceratops hatcheri Lull, side view 292 



XLVIII. Skull of Diceratops hatcheri, top view 294 



XLIX. Restoration of Triceratops. Photographs of mounted skeleton in United States National Museum.. 294 



L. Map showing principal Ceratopsia localities 294 



LI. Map of Converse County, Wyo 294 



Fig. 1. Type of Trachodon mirabilis Leidy 4 



2. Tooth of Monoclonius -' 4 



x 



