56 



THE CERATOPSIA 



Dimensions of Radius 



Length over all 345 mm. 



Greatest proximal width 83 



Greatest distal width 99 



Manus 

 (Figs. 24, 25) 



The left manus is almost entire, including the two carpalia, only five phalanges being missing 

 and these have been restored. The right manus, on the contrary, contains but two actual bones. 

 The bones of the manus differ very little from those described by Brown for C. nasicornus. 



Distally, the metacarpals are rugose, implying, as Brown has said, considerable cartilage there 

 as well as in the wrist, where but two small osseous elements were apparently present. These evi- 



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Fig. 24. — Anterior view of left fore foot of 

 Motwclonius {Centrosaurus) flexus, 1/6 natural size. 

 c, carpals; m, metacarpal; f x -f*-> phalanges; I-V, 

 digits. 



Fig. 25. — Lateral view of left fore foot of 

 Motwclonius (Centrosaurus) flexus, 1/6 natural size. 

 c, carpals; m, metacarpal; f 1 , first phalanx; f, 

 second phalanx; digits ///, IV, V. 



dently pertained to the distal row of carpalia. Of these the larger has more or less smooth opposite 

 surfaces, otherwise it is deeply pitted and irregular. The lesser carpal has about one-half the bulk 

 of the latter — a highly irregular nodule of bone. In Brown's restoration of the manus 2 the larger 

 carpal lies over the proximal end of metacarpal IV, the smaller over III. In the specimen of 

 Anchiceratofs in the Ottawa museum, which was found with all the skeletal bones articulated in situ, 

 the carpalia correspond both in number and position to those of Centrosaurus, which corroborates 

 Brown's description of what and where they were. The larger probably represents carpal IV, the 

 smaller carpal III. 



As the measurements show, the manus of the two specimens, C. nasicornus and C. flexus (Yale), 

 average about the same size. . 



The phalangeal formula was 2, 3, 4, 3, 2. Flattened ungual phalanges were borne on digits 

 I-III, those of IV and V being reduced to nodules only, but digit IV must have aided in bearing the 

 creature's weight and perhaps also digit V to a lesser extent. The entire foot was enclosed in a 

 weight-absorbing cushion although, unlike that of an elephant, the three hoofed digits protruded in 

 front as our restoration (PI. II), based in part on footprints, shows. 



28 Brown, B., 1917, PI. XII. 



