192 THE CERATOPSIA. 



Right hind limb and pelvis— Continued. Meters. 



Length of ischium (measured on outer curve) 1-50 



Breadth of proximal end. , 40 



Length of femur - - *■■ *■* 



Breadth of proximal end - 42 



Breadth of distal end - 43 



Girth of shaft - - 485 



Length of tibia and astragalus - 72 



Breadth of proximal end of tibia - - 395 



Breadth of distal end of tibia - - - - - 39 



Fibula ( restored ) - - 



Length of metatarsal II - - - - — 29 



Length of metatarsal III - - - - - - 355 



Length of digit III - - 325 



Length of ungual phalanx IV - H 



Breadth of ungual phalanx IV - - - - - - 12 



Measurements depending on posture: 



Height to summit of back 2. 47 



Breadth of shoulders at glenoid fossse - - - 1-25 



Breadth of elbows 2. 16 



Breadth across outer digits 1. 70 



Breadth across heads of femora - 1-50 



Breadth across knees - — - 1-93 



Breadth across outer digits - - 2. 04 



This skeleton has been admirably prepared and mounted by Mr. 'Gilmore. Two points, 

 however, are open to question, as is clearly recognized by Mr. Gilmore — the position of the 

 skull and that of the ischia. 



In the skull here mounted, as well as in the skulls of the type of Diceratops hatched, of 

 Triceratops calicomis, and of other species of Triceratops, the condyle, which is supported on a 

 neck, is strongly deflected downward in such a way as to cause the head to be carried low in 

 front if the line of the condyle is continuous with that of the cervicals, which it evidently should 

 be. The hemispherical articulating surface of the condyle is of such extent that the head 

 might have been raised to a somewhat higher position than that given it in the mount or, on 

 the other hand, depressed until the beak reached the ground, but the average position would 

 be with the muzzle about 20 inches (0.51 m.) lower than in the mounted position. In the 

 ischia the articulating extremities are of such a character that their exact method of union 

 with the ilia and pubes is highly conjectural, and further evidence from other specimens may 

 necessitate a radical departure from their position in the present mount. 



It seems probable that four is the correct number of digits in the maims rather than five 

 as in the mounted specimen. 



The cranial armature at once shows a sharp contrast in development and in mode of use 

 with that of the ancestral Monoclonius, for in Triceratops the frill was complete and heavy and 

 . undoubtedly flared upward and outward to a greater extent than in the former genus, affording 

 not only leverage for muscular attachment, but, as a helmet-like structure, serving to protect 

 the neck region from the horns of the adversary. In Triceratops, too, the temporal horns are 

 large and are strongly curved forward, with a corresponding reduction of the forward-directed 

 nasal horn. The restoration (PI. I, frontispiece) expresses well the appearance of the lowered 

 head, in which all three horns are brought to bear against the enemy at the moment of impact. 

 In Monoclonius the offensive stroke must have been an upward thrust in which the erect or 

 backward-curved nasal horn would prove a most efficient weapon, while Triceratops would 

 charge with lowered head, seeking either to impale his enemy or to bear the latter down by the 

 impetus of his great weight. 



The expansion of the frill and the development of great protecting ridges around the orbit 

 would be such as to best protect the most vital points, the neck and the eyes, from such a mode 

 of attack. 



