llll HIND LIMB AND FOOT 57 



Measurements of Manus 



Length of metacarpal I 



Length of metacarpal II 



Length of metacarpal III 



Length of metacarpal IV 



Length of metacarpal V 



Length of phalanx I, digit 1 



Length of phalanx I, digit 2 



Length of phalanx II, digit 1 



Length of phalanx II, digit 2 



Length of phalanx II, digit 3 



Length of phalanx III, digit 1 .• 



Length of phalanx III, digit 2 



Length of phalanx III, digit 3 



Length of phalanx III, digit 4 



Length of phalanx IV, digit 1 



Length of phalanx IV, digit 2 



Length of phalanx IV, digit 3 



Length of phalanx V, digit 1 



Length of phalanx V, digit 2 



Ilium 



(Figs. 17, 18) 



The ilia of Centrosaurus have much the same general form as in Triceratofs in that they are 

 elongated fore and aft and the blade is horizontal in position. In Centrosaurus that portion of the 

 blade forward of the pubic peduncle is relatively longer and more slender. Brown considers this a 

 generic character; it does differentiate Centrosaurus from Triceratofs, but not from Chasmosaurus, 

 with which he was apparently unfamiliar. Thus, in C. naskornus, as mounted, the forward 

 end of the ilium nearly covers the last presacral, as it does also in the Yale specimen and in the 

 C. cutleri type. In C. naskornus the ilium reaches the antipenultimate rib; in Chasmosaurus, it 

 covers the penultimate, but falls short of the rib in front, whereas in Anchkeratofs, it just over- 

 laps the last rib, but does not cover it. Doubtless the curvature of the ribs, as preserved, controls 

 this to some extent, but the evolutionary tendency seems to be a relative shortening of this portion 

 of the ilium; otherwise, the resemblance in all Ceratopsidae is very marked. The entire ilium has 

 a greater downward curve in the C. naskornus type, especially in this anterior portion, than in any 

 other known species. 



Pubis 



Both pubes ("Fig. 26) are well preserved in their entirety, including the postpubes. They arc 

 relatively more slender than in Triceratofs, especially in the distal half of the more elongate post- 

 pubis. The prepubis has a straight shaft which dilates toward the anterior end in a gentle curve in 

 contrast to the more abrupt widening in Triceratofs and in C. naskornus. The anterior margin is 

 somewhat curved, rugose, and apparently does not articulate with a rugosity on the penultimate rib 

 as it does in Chasmosaurus. The prepubes flare strongly outward so that the postpubes have a 

 decided curve proximally and are not in line with the prepubic shaft. The greatest vertical diameter 

 of the postpubis is at mid-length, whence it tapers in both directions, especially distal ly. 



Dimensions of Pubis 



C. ftrxus Y.P..M. C.neaeormu C. cutleri 



Length, excluding postpubis 434 mm. 450 mm. 500 mm. 



Length, including postpubis (measured on the chord) .... 617 



29 Artificial. 



