142 THE CERATOPSIA. 



with accuracy, there can not be fewer than nineteen. The postfrontal fontanelle is large and 

 circular in outline. The median longitudinal crest of the parietals is well defined and bears 

 the usual rugosities. Near the apex the right horn core has been worn into a peculiar form by 

 the long-continued action of wind, sand, and water while it protruded from the sandstone con- 

 cretion in which it was found. The palatal view shows no characters essentially different 

 from those of other species of this genus. In the region of the supraoccipitals and parietals 

 the sutures are so obliterated by age and obscured by distortion and crushing that it is quite 

 impossible to determine their nature. 



TJie lower jaw. — The lower jaws with the predentary were in position and in a splendid 

 state of preservation. The predentary is rather longer than is common. On the superior 

 surface of the mandibular fossa near the anterior end two large foramina pierce the wall and 

 pass upward toward the dental chamber. The splenial is very broad posteriorly and entirely 

 incloses the mandibular fossa, except at the opening of the internal mandibular foramen. 

 The coronoid process is low and stout, and superiorly it is produced forward into a broad and 

 somewhat decurved projection. At its greatest expansion the superior border of the splenial 

 covers over for a short distance the series of dental foramina on the inner side of the dentary. 

 The principal characters of the skull are well shown in Pis. XLI and XLII. 



THE VERTEBRAE. 



The vertebrae have been fully described in that portion of the present volume relating 

 to the osteology of the genus Triceratops (pp. 46-51). Their more important characters are 

 well shown in PI. XL, fig. 1 . 



Principal measurements of type ofT. brevicornus (No. 183^, Yale Museum). 



Mm. 



Greatest length of skull . . 1, 652 



Greatest breadth of frill J 1, 120 



Expanse of jugal 600 



Expanse of frontal region at anterior border of orbits ... 357 



Greatest diameter of orbit 16S 



Least diameter of orbit _ 120 



Fore-and-aft diameter of lateral temporal fossa. 105 



Vertical diameter of lateral temporal fossa 85 



Distance from posterior border of orbit to posterior border of frill 840 



Thickness of postfrontal behind orbit . 1.30 



Least antero-posterior diameter of horn core immediately above orbit 175 



Antero-posterior diameter of horn core 6 inches above orbit 117 



Transverse diameter of horn core immediately above orbit 140 



Transverse diameter of horn core 6 inches above orbit 97 



Greatest length of squamosal 870 



Greatest breadth of squamosal 433 



Length of parietals along median line 712 



Distance between squamosal sutures at posterior border of frill . _ 874 



Distance between squamosal sutures at junction with postfrontals . 330 



Distance from anterior border of orbit to posterior border of nasal opening 228 



Distance between orbit and lateral temporal foramen 142 



Distance between lateral and supratemporal foramina. . 285 



Distance from lateral temporal foramen to posterior border of squamosal 705 



Distance from occipital condyle to posterior margin of crest 650 



Distance from occipital condyle to interior border of rostral 975 



Distance from posterior border of anterior nares to anterior border of rostral 525 



Distance from postfrontal foramen to extremity of nasal horn 750 



Greatest expanse of exoccipital processes 550 



Distance from inferior border of orbit to bottom of jugal 343 



Diameter of occipital condyle .' 88 



Distance from mid-frontal region to apex of supraorbital horn 500 



Length of splenial 503 



Length of predentary 255 



Greatest breadth of predentary 142 



Combined length of dentary and predentary ." 681 



Combined length of dentary and articular 620 



Total length of presacral vertebral series 2, 290 



Total length of dorsal series 1, 490 



